INTERVIEW TIPS (questionnaire)

Note:- All questions-Answers  are collected by internet sites for only knowledge purpose.

HR Interview Questions For Freshers

·         Tell me about yourself.

·         Why should I hire you?

·         What are your strengths and weaknesses?

·         Why do you want to work at our company?

·         How do you feel about working nights and weekends?

·         Can you work under pressure?

·         Are you willing to relocate or travel?

·         What are your goals?

·         What motivates you to do good job?

·         What makes you angry?

·         Are not you overqualified for this position?

·         What is the difference between confidence and over confidence?

·         What is the difference between hard work and smart work?

·         Describe your ideal company, location and job.

·         What are your career options right now?

·         Explain how would be an asset to this organization?

·         What are your outside interests?

·         Give me an example of your creativity.

·         How long would you expect to work for us if hired?

·         What was the toughest decision you ever had to make?

·         Have you considered starting your own business?

·         How do you define success and how do you measure up to your own definition?

·         If you won $10 million lottery, would you still work?

·         Tell me something about our company.

·         How much salary do you expect?

·         Where do you see yourself five years from now?

·         Would you lie for the company?

·         Who has inspired you in your life and why?

·         On a scale of one to ten, rate me as an interviewer.

·         Do you have any questions for me?

HR Interview Questions For Experienced

·         Why did you resign from your previous job?

·         Why have you been out of work so long?

·         Could you have done better in your last job?

·         Tell me about the most boring job you have ever had.

·         May I contact your present employer for a reference?

·         How many hours a week do you normally work?

·         Why have you had so many jobs?

·         Tell me about a situation when your work was criticized.

·         What was the toughest challenge you have ever faced?

·         Have you been absent from work more than a few days in any previous position?

·         How could you have improved your career progress?

·         Tell me honestly about the strong points and weak points of your boss (company, management team, etc.)

·         Looking back on your last position, have you done your best work?

·         What changes would you make if you came on board?

·         What would you say to your boss if he is crazy about an idea, but you think it stinks?

·         Why should I hire you from the outside when I could promote someone from within?

·         Looking back, what would you do differently in your life?

·         How do you feel about reporting to a younger person?

·         Why are not you earning more money at this stage of your career?

Java basics Questions:-

1.       What is the difference between a constructor and a method?

A constructor is a member function of a class that is used to create objects of that class. It has the same name as the class itself, has no return type, and is invoked using the new operator.

A method is an ordinary member function of a class. It has its own name, a return type (which may be void), and is invoked using the dot operator.

2.       What is the purpose of garbage collection in Java, and when is it used?

The purpose of garbage collection is to identify and discard objects that are no longer needed by a program so that their resources can be reclaimed and reused.

A Java object is subject to garbage collection when it becomes unreachable to the program in which it is used.

3.       What is an abstract class?

Abstract class must be extended/subclasses (to be useful). It serves as a template. A class that is abstract may not be instantiated (ie. you may not call its constructor), abstract class may contain static data.

Any class with an abstract method is automatically abstract itself, and must be declared as such. A class may be declared abstract even if it has no abstract methods. This prevents it from being instantiated.

4.       Describe synchronization in respect to multithreading.

With respect to multithreading, synchronization is the capability to control the access of multiple threads to shared resources.

Without synchronization, it is possible for one thread to modify a shared variable while another thread is in the process of using or updating same shared variable. This usually leads to significant errors.

5.       What is the difference between an Interface and an Abstract class?

An abstract class can have instance methods that implement default behaviour. An Interface can only declare constants and instance methods, but cannot implement default behaviour and all methods are implicitly abstract.

7.An interface has all public members and no implementation. An abstract class is a class which may have the usual flavours of class members (private, protected, etc.), but has some abstract methods.

6.       Explain different way of using thread?

The thread could be implemented by using runnable interface or by inheriting from the Thread class. The former is more advantageous, 'cause when you are going for multiple inheritances, the only interface can help.

7.       What is static in java?

Static means one per class, not one for each object no matter how many instance of a class might exist. This means that you can use them without creating an instance of a class.Static methods are implicitly final, because overriding is done based on the type of the object, and static methods are attached to a class, not an object.

A static method in a superclass can be shadowed by another static method in a subclass, as long as the original method was not declared final. However, you can't override a static method with a nonstatic method. In other words, you can't change a static method into an instance method in a subclass.

8.       What is final class?

A final class can't be extended ie., final class may not be sub classed. A final method can't be overridden when its class is inherited. You can't change value of a final variable (is a constant).

9.       What if the main() method is declared as private?

The program compiles properly but at runtime it will give "main () method not public." message.

10.   What is an Iterator?

Some of the collection classes provide traversal of their contents via a java.util.Iterator interface. This interface allows you to walk through a collection of objects, operating on each object in turn.

Remember when using Iterators that they contain a snapshot of the collection at the time the Iterator was obtained; generally it is not advisable to modify the collection itself while traversing an Iterator.

11.   State the significance of public, private, protected, default modifiers both singly and in combination and state the effect of package relationships on declared items qualified by these modifiers.

Public: Public class is visible in other packages, field is visible everywhere (class must be public too)

Private: Private variables or methods may be used only by an instance of the same class that declares the variable or method; A private feature may only be accessed by the class that owns the feature.

Protected: Is available to all classes in the same package and also available to all subclasses of the class that owns the protected feature. This access is provided even to subclasses that reside in a different package from the class that owns the protected feature.

What you get by default ie, without any access modifier (i.e., public private or protected). It means that it is visible to all within a particular package.

12.   What if the static modifier is removed from the signature of the main () method?

Program compiles. But at run-time throws an error "NoSuchMethodError".

13.   What is the first argument of the String array in main() method?

The String array is empty. It does not have any element. This is unlike C/C++ where the first element by default is the program name.

14.   If I do not provide any arguments on the command line, then the String array of main() method will be empty or null?

It is empty. But not null.

15.   How can one prove that the array is not null but empty using one line of code?

Print args.length. It will print 0. That means it is empty. But if it would have been null then it would have thrown a NullPointerException on attempting to print args.length.

16.   What environment variables do I need to set on my machine in order to be able to run Java programs?

CLASSPATH and PATH are the two variables.

17.   What if I write static public void instead of public static void?

Program compiles and runs properly.

18.   What if I do not provide the String array as the argument to the method?

Program compiles but throws a runtime error "NoSuchMethodError".

19.   Can an application have multiple classes having main() method?

Yes it is possible. While starting the application we mention the class name to be run. The JVM will look for the Main method only in the class whose name you have mentioned.

Hence there is not conflict amongst the multiple classes having main () method.

20.   Can I have multiple main () methods in the same class?

No the program fails to compile. The compiler says that the main () method is already defined in the class.

21.   Do I need to import java? Lang package any time? Why?

No. It is by default loaded internally by the JVM.

22.   Can I import same package/class twice? Will the JVM load the package twice at runtime?

One can import the same package or same class multiple times. Neither compiler nor JVM complains about it. And the JVM will internally load the class only once no matter how many times you import the same class.

23.   What are Checked and UnChecked Exception?

A checked exception is some subclass of Exception (or Exception itself), excluding class Runtime Exception and its subclasses. Making an exception checked forces client programmers to deal with the possibility that the exception will be thrown.

Example: Exception thrown by java.io.FileInputStream's read () method·

Unchecked exceptions are Runtime Exception and any of its subclasses. Class Error and its subclasses also are unchecked. With an unchecked exception, however, the compiler doesn't force client programmers either to catch the exception or declare it in a throws clause. In fact, client programmers may not even know that the exception could be thrown.

Example: StringIndexOutOfBoundsException thrown by String's char at () method· Checked exceptions must be caught at compile time. Runtime exceptions do not need to be. Errors often cannot be.

24.   What is Overriding?

When a class defines a method using the same name, return type, and arguments as a method in its superclass, the method in the class overrides the method in the superclass.

When the method is invoked for an object of the class, it is the new definition of the method that is called, and not the method definition from superclass. Methods may be overridden to be more public, not more private.

25.   25. Are the imports checked for validity at compile time? Example: will the code containing an import such as java.lang.ABCD compile?

Yes the imports are checked for the semantic validity at compile time. The code containing above line of import will not compile. It will throw an error saying, cannot resolve symbol

symbol: class ABCD

Location: package io

Import java.io.ABCD;

26.   Does importing a package imports the sub packages as well? Example: Does importing com.MyTest.* also import com.MyTest.UnitTests.*?

No you will have to import the sub packages explicitly. Importing com.MyTest.* will import classes in the package My Test only. It will not import any class in any of its sub package.

27.   What is the difference between declaring a variable and defining a variable?

In declaration we just mention the type of the variable and it's name. We do not initialize it. But defining means declaration + initialization.

Example: String s; is just a declaration while String s = new String ("abcd"); Or String s = "abcd"; are both definitions.

28.   What is the default value of an object reference declared as an instance variable?

The default value will be null unless we define it explicitly.

29.   Can a top level class be private or protected?

No. A top level class cannot be private or protected. It can have either "public" or no modifier. If it does not have a modifier it is supposed to have a default access.

If a top level class is declared as private the compiler will complain that the "modifier private is not allowed here". This means that a top level class can not be private. Same is the case with protected.

30.   What type of parameter passing does Java support?

In Java the arguments are always passed by value.

31.   Primitive data types are passed by reference or pass by value?

Primitive data types are passed by value.

32.   Objects are passed by value or by reference?

Java only supports pass by value. With objects, the object reference itself is passed by value and so both the original reference and parameter copy both refer to the same object.

33.   What is serialization?

Serialization is a mechanism by which you can save the state of an object by converting it to a byte stream.

37.   37. What is the common usage of serialization?

Whenever an object is to be sent over the network, objects need to be serialized. Moreover if the state of an object is to be saved, objects need to be serilazed.

38.   What is Externalizable interface?

Externalizable is an interface which contains two methods readExternal and writeExternal. These methods give you a control over the serialization mechanism.

Thus if your class implements this interface, you can customize the serialization process by implementing these methods.

39.   When you serialize an object, what happens to the object references included in the object?

The serialization mechanism generates an object graph for serialization. Thus it determines whether the included object references are serializable or not. This is a recursive process.

Thus when an object is serialized, all the included objects are also serialized alongwith the original obect.

40.   What one should take care of while serializing the object?

One should make sure that all the included objects are also serializable. If any of the objects is not serializable then it throws a NotSerializableException.

41.   What happens to the static fields of a class during serialization?

There are three exceptions in which serialization doesnot necessarily read and write to the stream. These are

1. Serialization ignores static fields, because they are not part of ay particular state state.

2. Base class fields are only hendled if the base class itself is serializable.

3. Transient fields.

42.   Does Java provide any construct to find out the size of an object?

No, there is not sizeof operator in Java. So there is not direct way to determine the size of an object directly in Java.

43.   43. What are wrapper classes?

Java provides specialized classes corresponding to each of the primitive data types. These are called wrapper classes.

They are example: Integer, Character, Double etc.

44.   Why do we need wrapper classes?

It is sometimes easier to deal with primitives as objects. Moreover most of the collection classes store objects and not primitive data types. And also the wrapper classes provide many utility methods also.

Because of these resons we need wrapper classes. And since we create instances of these classes we can store them in any of the collection classes and pass them around as a collection. Also we can pass them around as method parameters where a method expects an object.

45.   What are checked exceptions?

Checked exception are those which the Java compiler forces you to catch.

Example: IOException are checked exceptions.

46.   What are runtime exceptions?

Runtime exceptions are those exceptions that are thrown at runtime because of either wrong input data or because of wrong business logic etc. These are not checked by the compiler at compile time.

47.   What is the difference between error and an exception?

An error is an irrecoverable condition occurring at runtime. Such as OutOfMemory error.

These JVM errors and you can not repair them at runtime. While exceptions are conditions that occur because of bad input etc. Example: FileNotFoundException will be thrown if the specified file does not exist. Or a NullPointerException will take place if you try using a null reference.

In most of the cases it is possible to recover from an exception (probably by giving user a feedback for entering proper values etc.).

48.   How to create custom exceptions?

Your class should extend class Exception, or some more specific type thereof.

49.   49. If I want an object of my class to be thrown as an exception object, what should I do?

The class should extend from Exception class. Or you can extend your class from some more precise exception type also.

50.   If my class already extends from some other class what should I do if I want an instance of my class to be thrown as an exception object?

One can not do anytihng in this scenarion. Because Java does not allow multiple inheritance and does not provide any exception interface as well.

51.   How does an exception permeate through the code?

An unhandled exception moves up the method stack in search of a matching When an exception is thrown from a code which is wrapped in a try block followed by one or more catch blocks, a search is made for matching catch block. If a matching type is found then that block will be invoked. If a matching type is not found then the exception moves up the method stack and reaches the caller method.

Same procedure is repeated if the caller method is included in a try catch block. This process continues until a catch block handling the appropriate type of exception is found. If it does not find such a block then finally the program terminates.

52.   What are the different ways to handle exceptions?

There are two ways to handle exceptions,

1. By wrapping the desired code in a try block followed by a catch block to catch the exceptions. and

2. List the desired exceptions in the throws clause of the method and let the caller of the method hadle those exceptions.

53.   Is it necessary that each try block must be followed by a catch block?

It is not necessary that each try block must be followed by a catch block. It should be followed by either a catch block or a finally block. And whatever exceptions are likely to be thrown should be declared in the throws clause of the method.

54.   If I write return at the end of the try block, will the finally block still execute?

Yes even if you write return as the last statement in the try block and no exception occurs, the finally block will execute. The finally block will execute and then the control return.

55.   55. If I write System.exit(0); at the end of the try block, will the finally block still execute?

No. In this case the finally block will not execute because when you say System.exit(0); the control immediately goes out of the program, and thus finally never executes.

56.   How are Observer and Observable used?

Objects that subclass the Observable class maintain a list of observers. When an Observable object is updated it invokes the update() method of each of its observers to notify the observers that it has changed state. The Observer interface is implemented by objects that observe Observable objects.

57.   What is synchronization and why is it important?

With respect to multithreading, synchronization is the capability to control the access of multiple threads to shared resources.

Without synchronization, it is possible for one thread to modify a shared object while another thread is in the process of using or updating that object's value. This often leads to significant errors.

58.   How does Java handle integer overflows and underflows?

It uses those low order bytes of the result that can fit into the size of the type allowed by the operation.

59.   Does garbage collection guarantee that a program will not run out of memory?

Garbage collection does not guarantee that a program will not run out of memory. It is possible for programs to use up memory resources faster than they are garbage collected. It is also possible for programs to create objects that are not subject to garbage collection.

60.   What is the difference between preemptive scheduling and time slicing?

Under preemptive scheduling, the highest priority task executes until it enters the waiting or dead states or a higher priority task comes into existence.

Under time slicing, a task executes for a predefined slice of time and then reenters the pool of ready tasks. The scheduler then determines which task should execute next, based on priority and other factors.

Software engineering Questions:-

Q.What is computer software?

A. Computer software is a complete package, which includes software program, its documentation and user guide on how to use the software.

Q.Can you differentiate computer software and computer program?

A. A computer program is piece of programming code which performs a well defined task where as software includes programming code, its documentation and user guide.

Q.What is software engineering?

A. Software engineering is an engineering branch associated with software system development.

Q.When you know programming, what is the need to learn software engineering concepts?

A. A person who knows how to build a wall may not be good at building an entire house. Likewise, a person who can write programs may not have knowledge of other concepts of Software Engineering. The software engineering concepts guide programmers on how to assess requirements of end user, design the algorithms before actual coding starts, create programs by coding, testing the code and its documentation.

Q.What is software process or Software Development Life Cycle (SDLC)?

A.Software Development Life Cycle, or software process is the systematic development of software by following every stage in the development process namely, Requirement Gathering, System Analysis, Design, Coding, Testing, Maintenance and Documentation in that order.

Q.What are SDLC models available?

A. There are several SDLC models available such as Waterfall Model, Iterative Model, Spiral model, V-model and Big-bang Model etc.

Q.What are various phases of SDLC?

A. The generic phases of SDLC are: Requirement Gathering, System Analysis and Design, Coding, Testing and implementation. The phases depend upon the model we choose to develop software.

Q.Which SDLC model is the best?

A. SDLC Models are adopted as per requirements of development process. It may very software-to-software to ensuring which model is suitable.

We can select the best SDLC model if following answers are satisfied -

• Is SDLC suitable for selected technology to implement the software ?
• Is SDLC appropriate for client’s requirements and priorities ?
• Is SDLC model suitable for size and complexity of the software ?
• Is the SDLC model suitable for type of projects and engineering we do ?
• Is the SDLC appropriate for the geographically co-located or dispersed developers ?

Q.What is software project management?

A. Software project management is process of managing all activities like time, cost and quality management involved in software development.

Q.Who is software project manager?

A. A software project manager is a person who undertakes the responsibility of carrying out the software project.

Q.What does software project manager do?

A. Software project manager is engaged with software management activities. He is responsible for project planning, monitoring the progress, communication among stakeholders, managing risks and resources, smooth execution of development and delivering the project within time, cost and quality contraints.

Q.What is software scope?

A. Software scope is a well-defined boundary, which encompasses all the activities that are done to develop and deliver the software product.

The software scope clearly defines all functionalities and artifacts to be delivered as a part of the software. The scope identifies what the product will do and what it will not do, what the end product will contain and what it will not contain.

Q.What is project estimation?

A. It is a process to estimate various aspects of software product in order to calculate the cost of development in terms of efforts, time and resources. This estimation can be derived from past experience, by consulting experts or by using pre-defined formulas.

Q.How can we derive the size of software product?

A. Size of software product can be calculated using either of two methods -

• Counting the lines of delivered code
• Counting delivered function points

Q.What are function points?

A. Function points are the various features provided by the software product. It is considered as a unit of measurement for software size.

Q.What are software project estimation techniques available?

A. There are many estimation techniques available.The most widely used are -

• Decomposition technique (Counting Lines of Code and Function Points)
• Empirical technique (Putnam and COCOMO).

Q.What is baseline?

A. Baseline is a measurement that defines completeness of a phase. After all activities associated with a particular phase are accomplished, the phase is complete and acts as a baseline for next phase.

Q.What is Software configuration management?

A. Software Configuration management is a process of tracking and controlling the changes in software in terms of the requirements, design, functions and development of the product.

Q.What is change control?

A. Change control is function of configuration management, which ensures that all changes made to software system are consistent and made as per organizational rules and regulations.

Q.How can you measure project execution?

A. We can measure project execution by means of Activity Monitoring, Status Reports and Milestone Checklists.

Q.Mention some project management tools.

A. There are various project management tools used as per the requirements of software project and organization policies. They include Gantt Chart, PERT Chart, Resource Histogram, Critical Path Analysis, Status Reports, Milestone Checklists etc.

Q.What are software requirements?

A. Software requirements are functional description of proposed software system. Requirements are assumed to be the description of target system, its functionalities and features. Requirements convey the expectations of users from the system.

Q.What is feasibility study?

A. It is a measure to assess how practical and beneficial the software project development will be for an organization. The software analyzer conducts a thorough study to understand economic, technical and operational feasibility of the project.

·        Economic - Resource transportation, cost for training, cost of additional utilities and tools and overall estimation of costs and benefits of the project.

·        Technical - Is it possible to develop this system ? Assessing suitability of machine(s) and operating system(s) on which software will execute, existing developers’ knowledge and skills, training, utilities or tools for project.

·        Operational - Can the organization adjust smoothly to the changes done as per the demand of project ? Is the problem worth solving ?

Q.How can you gather requirements?

A. Requirements can be gathered from users via interviews, surveys, task analysis, brainstorming, domain analysis, prototyping, studying existing usable version of software, and by observation.

Q.What is SRS?

A. SRS or Software Requirement Specification is a document produced at the time of requirement gathering process. It can be also seen as a process of refining requirements and documenting them.

Q.What are functional requirements?

A. Functional requirements are functional features and specifications expected by users from the proposed software product.

Q.What are non-functional requirements?

A. Non-functional requirements are implicit and are related to security, performance, look and feel of user interface, interoperability, cost etc.

Q.What is software measure?

A. Software Measures can be understood as a process of quantifying and symbolizing various attributes and aspects of software.

Q.What is software metric?

A. Software Metrics provide measures for various aspects of software process and software product. They are divided into –

• Requirement metrics : Length requirements, completeness
• Product metrics :Lines of Code, Object oriented metrics, design and test metrics
• Process metrics: Evaluate and track budget, schedule, human resource.

Q.What is modularization?

A. Modularization is a technique to divide a software system into multiple discreet modules, which are expected to carry out task(s) independently.

Q.What is concurrency and how it is achieved in software?

A. Concurrency is the tendency of events or actions to happen simultaneously. In software, when two or more processes execute simultaneously, they are called concurrent processes.

Example

While you initiate print command and printing starts, you can open a new application.

Concurrency, is implemented by splitting the software into multiple independent units of execution namely processes and threads, and executing them in parallel.

Q.What is cohesion?

A. Cohesion is a measure that defines the degree of intra-dependability among the elements of the module.

Q.What is coupling?

A. Coupling is a measure that defines the level of inter-dependability among modules of a program.

Q.Mentions some software analysis & design tools?

A. These can be: DFDs (Data Flow Diagrams), Structured Charts, Structured English, Data Dictionary, HIPO (Hierarchical Input Process Output) diagrams, ER (Entity Relationship) Diagrams and Decision tables.

Q.What is level-0 DFD?

A. Highest abstraction level DFD is known as Level 0 DFD also called a context level DFD, which depicts the entire information system as one diagram concealing all the underlying details.

Q.What is the difference between structured English and Pseudo Code?

A. Structured English is native English language used to write the structure of a program module by using programming language keywords, whereas, Pseudo Code is more close to programming language and uses native English language words or sentences to write parts of code.

Q.What is data dictionary?

A. Data dictionary is referred to as meta-data. Meaning, it is a repository of data about data. Data dictionary is used to organize the names and their references used in system such as objects and files along with their naming conventions.

Q.What is structured design?

A. Structured design is a conceptualization of problem into several well-organized elements of solution. It is concern with the solution design and based on ‘divide and conquer’ strategy.

Q.What is the difference between function oriented and object oriented design?

A. Function-oriented design is comprised of many smaller sub-systems known as functions. Each function is capable of performing significant task in the system. Object oriented design works around the real world objects (entities), their classes (categories) and methods operating on objects (functions).

Q.Briefly define top-down and bottom-up design model.

A. Top-down model starts with generalized view of system and decomposes it to more specific ones, whereas bottom-up model starts with most specific and basic components first and keeps composing the components to get higher level of abstraction.

Q.What is the basis of Halstead’s complexity measure?

A. Halstead’s complexity measure depends up on the actual implementation of the program and it considers tokens used in the program as basis of measure.

Q.Mention the formula to calculate Cyclomatic complexity of a program?

A. Cyclomatic complexity uses graph theory’s formula: V(G) = e – n + 2

Q.What is functional programming?

A. Functional programming is style of programming language, which uses the concepts of mathematical function. It provides means of computation as mathematical functions, which produces results irrespective of program state.

Q.Differentiate validation and verification?

A. Validation checks if the product is made as per user requirements whereas verification checks if proper steps are followed to develop the product.

Validation confirms the right product and verification confirms if the product is built in a right way.

Q.What is black-box and white-box testing?

A. Black-box testing checks if the desired outputs are produced when valid input values are given. It does not verify the actual implementation of the program.

White-box testing not only checks for desired and valid output when valid input is provided but also it checks if the code is implemented correctly.

Criteria	Black Box Testing	White Box Testing
Knowledge of software program, design and structure essential	No	Yes
Knowledge of Software Implementation essential	No	Yes
Who conducts this test on software	Software Testing Employee	Software Developer
baseline reference for tester	Requirements specifications	Design and structure details

Q.Quality assurance vs. Quality Control?

A. Quality Assurance monitors to check if proper process is followed while software developing the software.

Quality Control deals with maintaining the quality of software product.

Q.What are various types of software maintenance?

A. Maintenance types are: corrective, adaptive, perfective and preventive.

• Corrective

Removing errors spotted by users

• Adaptive

tackling the changes in the hardware and software environment where the software works

• Perfective maintenance

implementing changes in existing or new requirements of user

• Preventive maintenance

taking appropriate measures to avoid future problems

Q.What is software re-engineering?

A. Software re-engineering is process to upgrade the technology on which the software is built without changing the functionality of the software. This is done in order to keep the software tuned with the latest technology.

Q.What are CASE tools?

A. CASE stands for Computer Aided Software Engineering. CASE tools are set of automated software application programs, which are used to support, accelerate and smoothen the SDLC activities.

What is the full form of COCOMO? (A) Composite Cost Model (B) Constructive Cost Model (C) Constructive Composite Model (D) Comprehensive Construction Model ANSWER: B Cyclometric complexity of a flow graph G with n vertices and e edges is defined as: (A) V(G) = e+n–2 (B) V(G) = e–n+2 (C) V(G) = e+n+2 (D) V(G) = e–n–2 ANSWER: B

A good software design must have the following attribute. (A) High module coupling, high module cohesion. (B) High module coupling, low module cohesion. (C) Low module coupling, high module cohesion. (D) Low module coupling, low module cohesion. ANSWER: C While estimating the cost of software, Lines Of Code (LOC) and Function Points (FP) are used to measure which one of the following? (A) Length of code (B) Size of software (C) Functionality of software (D) None of the above ANSWER: B

Match the correct code regarding the software: a. Good quality--------i. Program does not fail for a specified time in a given environment b. Correctness---------ii. Meets the functional requirements of software c. Predictable----------iii. Meets both functional and non-functional requirements of software d. Reliable-------------iv. Process is under statistical control Codes: (A) a - iii, b - ii, c - iv, d - i (B) a - ii, b - iii, c - iv, d - i (C) a - i, b - ii, c - iv, d - iii (D) a - i, b - ii, c - iii, d - iv ANSWER: A Which process model that removes defects before software get into trouble? (A) Incremental model? (B) Spiral model (C) Clean room software engineering (D) Agile model ANSWER: C

The given below line are three golden rules. Choose the correct answer from A,B,C and D: (i) Place the user in control. (ii) Reduce the user’s memory load. (iii) Make the interface consistent. (A) User satisfaction (B) Good interface design (C) Saving system’s resources (D) None of these ANSWER: B Which Software safety activity that focuses on the identification and assessment of potential hazards that may affect software negatively and cause an entire system to fail? (A) Risk mitigation, monitoring and management (B) Software quality assurance (C) Software cost estimation (D) Defect removal efficiency ANSWER: B

The Software Maturity Index (SMI) is defined as SMI = [MT – (Fa + Fc + Fd)] / MT Where MT = the number of modules in the current release. Fa = the number of modules in the current release that have been added. Fc = the number of modules in the current release that have been changed. Fd = the number of modules in the current release that have been deleted. The product begins to stabilize when (A) SMI approaches 2 (B) SMI approaches 0 (C) SMI approaches –1 (D) SMI approaches 1 ANSWER: D Consider the following characteristics and choose one option that is true for a good SRS (Software Requirement Specification). (i) Correct and unambiguous (ii) Complete and consistent (iii) Ranked for importance and/or stability and verifiable (iv) Modifiable and Traceable (A) (i), (ii) and (iii) (B) (i), (iii) and (iv) (C) (ii), (iii) and (iv) (D) All of the above ANSWER: D

The relationship of data elements in a module is called (A) Data Coupling (B) Modularity (C) Cohesion (D) Module Binding ANSWER: C Software Configuration Management is the discipline for systematically controlling (A) The changes due to the evolution of work products as the project proceeds. (B) The changes due to defects (bugs) being found and then fixed. (C) The changes due to requirement changes (D) all of the above ANSWER: D

Which one of the following is not a step of requirement engineering? (A) Requirement elicitation (B) Requirement analysis (C) Requirement design (D) Requirement documentation. ANSWER: C Given a flow graph with 10 nodes, 13 edges and one connected components, the number of regions and the number of predicate (decision) nodes in the flow graph will be (A) 4, 5 (B) 5, 4 (C) 3, 1 (D) 13, 8 ANSWER: B

A process that have the following four primary objectives are: 1. To identify all items that collectively defines the software configuration. 2. To manage changes to one or more of these items. 3. To facilitate the construction of different versions of an application. 4. To ensure that software quality is maintained as the configuration evolves over time. Identify that process and choose one option. (A) Software Quality Management Process (B) Software Configuration Management Process (C) Software Version Management Process (D) Software Change Management Process ANSWER: B Read List-1 and List-2 and Match the following:           List – I --------------------------------------- List – II a. Data coupling--------------------------- i. Module A and Module B have shared data b. Stamp coupling------------------------- ii. Dependency between modules is based on the fact they communicate by only passing of data c. Common coupling--------------------- iii. When complete data structure is passed from one module to another d. Content coupling ---------------------- iv. When the control is passed from one module to the middle of anotherCodes : (A) a - iii, b - ii, c - i, d - iv (B) a - ii, b - iii, c - i, d - iv (C) a - ii, b - iii, c - iv, d - i (D) a - iii, b - ii, c - iv, d - i ANSWER: B

In an examination a candidate has to score minimum of 25 marks in order to clear the exam. The maximum that he can score is 50 marks. Identify the Valid Equivalence values if the student clears the exam. a) 22, 23, 26 b) 21, 39, 40 c) 29, 30, 31 d) 0, 15, 22 ANSWER: C Which one of the following is not a software myth? (A) Once we write the program and get it to work, our job is done. (B) Project requirements continually change, but change can be easily accommodated because software is flexible. (C) If we get behind schedule, we can add more programmers and catch up. (D) If an organization does not understand how to control software projects internally, it will invariably struggle when it outsources software projects. ANSWER: D

Match the following style rules for reusability:              List – I ------------------------------------------------------ List – II a. Keep methods coherent --------------------------- i. Write a method to get the element of a list b. Keep methods small ------------------------------- ii. Maintain parallel structure when possible c. Keep methods consistent ------------------------- iii. Do not break a method into smaller parts d. Provide uniform coverage ------------------------- iv. Performs a single function or a group of closely related functions. Codes : (A) a - iv, b - iii, c - ii, d - i (B) a - ii, b - i, c - iv, d - iii (C) a - iii, b - iv, c - ii, d - i (D) None of the above ANSWER: D Coding phase of software product development life cycle essentially involves: (A) Integration of hardware and software (B) Integration of feasibility study (C) Integration of maintenance stage (D) Integration of system engineering stage ANSWER: A

1 2

Networking Questions

1.       Define Network?

A network is a set of devices connected by physical media links. A network is recursively is a connection of two or more nodes by a physical link or two or more networks connected by one or more nodes.

2.       What is a Link?

At the lowest level, a network can consist of two or more computers directly connected by some physical medium such as coaxial cable or optical fiber. Such a physical medium is called as Link.

3.       What is a node?

A network can consist of two or more computers directly connected by some physical medium such as coaxial cable or optical fiber. Such a physical medium is called as Links and the computer it connects is called as Nodes.

4.       What is a gateway or Router?

A node that is connected to two or more networks is commonly called as router or Gateway. It generally forwards message from one network to another.

5.       What is point-point link?

If the physical links are limited to a pair of nodes it is said to be point-point link.

6.       What is Multiple Access?

If the physical links are shared by more than two nodes, it is said to be Multiple Access.

7.       7. What are the advantages of Distributed Processing?

a. Security/Encapsulation
b. Distributed database
c. Faster Problem solving
d. Security through redundancy
e. Collaborative Processing

8.       What are the criteria necessary for an effective and efficient network?

a. Performance
   It can be measured in many ways, including transmit time and response time. b. Reliability
   It is measured by frequency of failure, the time it takes a link to recover from a failure, and the network's robustness.
c. Security
   Security issues includes protecting data from unauthorized access and virues.

9.       Name the factors that affect the performance of the network?

a. Number of Users
b. Type of transmission medium
c. Hardware
d. Software

10.   Name the factors that affect the reliability of the network?

a. Frequency of failure
b. Recovery time of a network after a failure

11.   Name the factors that affect the security of the network?

a. Unauthorized Access
b. Viruses

12.   What is Protocol?

A protocol is a set of rules that govern all aspects of information communication.

13.   13. What are the key elements of protocols?

The key elements of protocols are
a. Syntax
   It refers to the structure or format of the data, that is the order in which they are presented.
b. Semantics
   It refers to the meaning of each section of bits.
c. Timing
   Timing refers to two characteristics: When data should be sent and how fast they can be sent.

14.   What are the key design issues of a computer Network?

a. Connectivity
b. Cost-effective Resource Sharing
c. Support for common Services
d. Performance

15.   Define Bandwidth and Latency?

Network performance is measured in Bandwidth (throughput) and Latency (Delay). Bandwidth of a network is given by the number of bits that can be transmitted over the network in a certain period of time. Latency corresponds to how long it t5akes a message to travel from one end off a network to the other. It is strictly measured in terms of time.

16.   Define Routing?

The process of determining systematically hoe to forward messages toward the destination nodes based on its address is called routing.

17.   What is a peer-peer process?

The processes on each machine that communicate at a given layer are called peer-peer process.

18.   When a switch is said to be congested?

It is possible that a switch receives packets faster than the shared link can accommodate and stores in its memory, for an extended period of time, then the switch will eventually run out of buffer space, and some packets will have to be dropped and in this state is said to congested state.

19.   19. What is semantic gap?

Defining a useful channel involves both understanding the applications requirements and recognizing the limitations of the underlying technology. The gap between what applications expects and what the underlying technology can provide is called semantic gap.

20.   What is Round Trip Time?

The duration of time it takes to send a message from one end of a network to the other and back, is called RTT.

21.   Define the terms Unicasting, Multiccasting and Broadcasting?

If the message is sent from a source to a single destination node, it is called Unicasting.
If the message is sent to some subset of other nodes, it is called Multicasting.
If the message is sent to all the m nodes in the network it is called Broadcasting.

22.   What is Multiplexing?

Multiplexing is the set of techniques that allows the simultaneous transmission of multiple signals across a single data link.

23.   Name the categories of Multiplexing?

a. Frequency Division Multiplexing (FDM)
b. Time Division Multiplexing (TDM)
   i. Synchronous TDM
   ii. ASynchronous TDM Or Statistical TDM.
c. Wave Division Multiplexing (WDM)

24.   What is FDM?

FDM is an analog technique that can be applied when the bandwidth of a link is greater than the combined bandwidths of the signals to be transmitted.

25.   25. What is WDM?

WDM is conceptually the same as FDM, except that the multiplexing and demultiplexing involve light signals transmitted through fiber optics channel.

26.   What is TDM?

TDM is a digital process that can be applied when the data rate capacity of the transmission medium is greater than the data rate required by the sending and receiving devices.

27.   What is Synchronous TDM?

In STDM, the multiplexer allocates exactly the same time slot to each device at all times, whether or not a device has anything to transmit.

28.   List the layers of OSI

a. Physical Layer
b. Data Link Layer
c. Network Layer
d. Transport Layer
e. Session Layer
f. Presentation Layer
g. Application Layer

29.   Which layers are network support layers?

a. Physical Layer
b. Data link Layer and
c. Network Layers

30.   Which layers are user support layers?

a. Session Layer
b. Presentation Layer and
c. Application Layer

31.   31. Which layer links the network support layers and user support layers?

The Transport layer links the network support layers and user support layers.

32.   What are the concerns of the Physical Layer?

Physical layer coordinates the functions required to transmit a bit stream over a physical medium.
a. Physical characteristics of interfaces and media
b. Representation of bits
c. Data rate
d. Synchronization of bits
e. Line configuration
f. Physical topology
g. Transmission mode

33.   What are the responsibilities of Data Link Layer?

The Data Link Layer transforms the physical layer, a raw transmission facility, to a reliable link and is responsible for node-node delivery.
a. Framing
b. Physical Addressing
c. Flow Control
d. Error Control
e. Access Control

34.   What are the responsibilities of Network Layer?

The Network Layer is responsible for the source-to-destination delivery of packet possibly across multiple networks (links).
a. Logical Addressing
b. Routing

35.   What are the responsibilities of Transport Layer?

The Transport Layer is responsible for source-to-destination delivery of the entire message.
a. Service-point Addressing
b. Segmentation and reassembly
c. Connection Control
d. Flow Control
e. Error Control

36.   What are the responsibilities of Session Layer?

The Session layer is the network dialog Controller. It establishes, maintains and synchronizes the interaction between the communicating systems.
a. Dialog control
b. Synchronization

37.   37. What are the responsibilities of Presentation Layer?

The Presentation layer is concerned with the syntax and semantics of the information exchanged between two systems.
a. Translation
b. Encryption
c. Compression

38.   What are the responsibilities of Application Layer?

The Application Layer enables the user, whether human or software, to access the network. It provides user interfaces and support for services such as e-mail, shared database management and other types of distributed information services.
a. Network virtual Terminal
b. File transfer, access and Management (FTAM)
c. Mail services
d. Directory Services

39.   What are the two classes of hardware building blocks?

Nodes and Links.

40.   What are the different link types used to build a computer network?

a. Cables
b. Leased Lines
c. Last-Mile Links
d. Wireless Links

41.   What are the categories of Transmission media?

a. Guided Media
  i. Twisted - Pair cable
    1. Shielded TP
    2. Unshielded TP
  ii. Coaxial Cable
  iii. Fiber-optic cable
b. Unguided Media
  i. Terrestrial microwave
  ii. Satellite Communication

42.   What are the types of errors?

a. Single-Bit error
  In a single-bit error, only one bit in the data unit has changed
b. Burst Error
  A Burst error means that two or more bits in the data have changed.

43.   43. What is Error Detection? What are its methods?

Data can be corrupted during transmission. For reliable communication errors must be deducted and Corrected. Error Detection uses the concept of redundancy, which means adding extra bits for detecting errors at the destination. The common Error Detection methods are
  a. Vertical Redundancy Check (VRC)
  b. Longitudinal Redundancy Check (VRC)
  c. Cyclic Redundancy Check (VRC)
  d. Checksum

44.   What is Redundancy?

The concept of including extra information in the transmission solely for the purpose of comparison. This technique is called redundancy.

45.   What is VRC?

It is the most common and least expensive mechanism for Error Detection. In VRC, a parity bit is added to every data unit so that the total number of 1s becomes even for even parity. It can detect all single-bit errors. It can detect burst errors only if the total number of errors in each data unit is odd.

46.   What is LRC?

In LRC, a block of bits is divided into rows and a redundant row of bits is added to the whole block. It can detect burst errors. If two bits in one data unit are damaged and bits in exactly the same positions in another data unit are also damaged, the LRC checker will not detect an error. In LRC a redundant data unit follows n data units.

47.   What is CRC?

CRC, is the most powerful of the redundancy checking techniques, is based on binary division.

48.   What is Checksum?

Checksum is used by the higher layer protocols (TCP/IP) for error detection

49.   49. List the steps involved in creating the checksum.

a. Divide the data into sections
b. Add the sections together using 1's complement arithmetic
c. Take the complement of the final sum, this is the checksum.

50.   What are the Data link protocols?

Data link protocols are sets of specifications used to implement the data link layer. The categories of Data Link protocols are 1. Asynchronous Protocols
2. Synchronous Protocols
  a. Character Oriented Protocols
  b. Bit Oriented protocols

51.   Compare Error Detection and Error Correction:

The correction of errors is more difficult than the detection. In error detection, checks only any error has occurred. In error correction, the exact number of bits that are corrupted and location in the message are known. The number of the errors and the size of the message are important factors.

52.   What is Forward Error Correction?

Forward error correction is the process in which the receiver tries to guess the message by using redundant bits.

53.   Define Retransmission?

Retransmission is a technique in which the receiver detects the occurrence of an error and asks the sender to resend the message. Resending is repeated until a message arrives that the receiver believes is error-freed.

54.   What are Data Words?

In block coding, we divide our message into blocks, each of k bits, called datawords. The block coding process is one-to-one. The same dataword is always encoded as the same codeword.

55.   55. What are Code Words?

"r" redundant bits are added to each block to make the length n = k + r. The resulting n-bit blocks are called codewords. 2ⁿ - 2^k codewords that are not used. These codewords are invalid or illegal.

56.   What is a Linear Block Code?

A linear block code is a code in which the exclusive OR (addition modulo-2) of two valid codewords creates another valid codeword.

57.   What are Cyclic Codes?

Cyclic codes are special linear block codes with one extra property. In a cyclic code, if a codeword is cyclically shifted (rotated), the result is another codeword.

58.   Define Encoder?

A device or program that uses predefined algorithms to encode, or compress audio or video data for storage or transmission use. A circuit that is used to convert between digital video and analog video.

59.   Define Decoder?

A device or program that translates encoded data into its original format (e.g. it decodes the data). The term is often used in reference to MPEG-2 video and sound data, which must be decoded before it is output.

60.   What is Framing?

Framing in the data link layer separates a message from one source to a destination, or from other messages to other destinations, by adding a sender address and a destination address. The destination address defines where the packet has to go and the sender address helps the recipient acknowledge the receipt.

61.   61. What is Fixed Size Framing?

In fixed-size framing, there is no need for defining the boundaries of the frames. The size itself can be used as a delimiter.

62.   Define Character Stuffing?

In byte stuffing (or character stuffing), a special byte is added to the data section of the frame when there is a character with the same pattern as the flag. The data section is stuffed with an extra byte. This byte is usually called the escape character (ESC), which has a predefined bit pattern. Whenever the receiver encounters the ESC character, it removes it from the data section and treats the next character as data, not a delimiting flag.

63.   What is Bit Stuffing?

Bit stuffing is the process of adding one extra 0 whenever five consecutive Is follow a 0 in the data, so that the receiver does not mistake the pattern 0111110 for a flag.

64.   What is Flow Control?

Flow control refers to a set of procedures used to restrict the amount of data that the sender can send before waiting for acknowledgment.

65.   What is Error Control ?

Error control is both error detection and error correction. It allows the receiver to inform the sender of any frames lost or damaged in transmission and coordinates the retransmission of those frames by the sender. In the data link layer, the term error control refers primarily to methods of error detection and retransmission.

66.   What Automatic Repeat Request (ARQ)?

Error control is both error detection and error correction. It allows the receiver to inform the sender of any frames lost or damaged in transmission and coordinates the retransmission of those frames by the sender. In the data link layer, the term error control refers primarily to methods of error detection and retransmission. Error control in the data link layer is often implemented simply: Any time an error is detected in an exchange, specified frames are retransmitted. This process is called automatic repeat request (ARQ).

67.   67. What is Stop-and-Wait Protocol?

In Stop and wait protocol, sender sends one frame, waits until it receives confirmation from the receiver (okay to go ahead), and then sends the next frame.

68.   What is Stop-and-Wait Automatic Repeat Request?

Error correction in Stop-and-Wait ARQ is done by keeping a copy of the sent frame and retransmitting of the frame when the timer expires.

69.   What is usage of Sequence Number in Relaible Transmission?

The protocol specifies that frames need to be numbered. This is done by using sequence numbers. A field is added to the data frame to hold the sequence number of that frame. Since we want to minimize the frame size, the smallest range that provides unambiguous communication. The sequence numbers can wrap around.

70.   What is Pipelining ?

In networking and in other areas, a task is often begun before the previous task has ended. This is known as pipelining.

71.   What is Sliding Window?

The sliding window is an abstract concept that defines the range of sequence numbers that is the concern of the sender and receiver. In other words, he sender and receiver need to deal with only part of the possible sequence numbers.

72.   What is Piggy Backing?

A technique called piggybacking is used to improve the efficiency of the bidirectional protocols. When a frame is carrying data from A to B, it can also carry control information about arrived (or lost) frames from B; when a frame is carrying data from B to A, it can also carry control information about the arrived (or lost) frames from A.

73.   73. What are the two types of transmission technology available?

(i) Broadcast and (ii) point-to-point

74.   What is subnet?

A generic term for section of a large networks usually separated by a bridge or router.

75.   Difference between the communication and transmission.

Transmission is a physical movement of information and concern issues like bit polarity, synchronisation, clock etc.

Communication means the meaning full exchange of information between two communication media.

76.   What are the possible ways of data exchange?

(i) Simplex (ii) Half-duplex (iii) Full-duplex.

77.   What is SAP?

Series of interface points that allow other computers to communicate with the other layers of network protocol stack.

78.   What do you meant by "triple X" in Networks?

The function of PAD (Packet Assembler Disassembler) is described in a document known as X.3. The standard protocol has been defined between the terminal and the PAD, called X.28; another standard protocol exists between hte PAD and the network, called X.29. Together, these three recommendations are often called "triple X".

79.   79. What is frame relay, in which layer it comes?

Frame relay is a packet switching technology. It will operate in the data link layer.

80.   What is terminal emulation, in which layer it comes?

Telnet is also called as terminal emulation. It belongs to application layer.

81.   What is Beaconing?

The process that allows a network to self-repair networks problems. The stations on the network notify the other stations on the ring when they are not receiving the transmissions. Beaconing is used in Token ring and FDDI networks.

82.   What is redirector?

Redirector is software that intercepts file or prints I/O requests and translates them into network requests. This comes under presentation layer.

83.   What is NETBIOS and NETBEUI?

NETBIOS is a programming interface that allows I/O requests to be sent to and received from a remote computer and it hides the networking hardware from applications.

NETBEUI is NetBIOS extended user interface. A transport protocol designed by microsoft and IBM for the use on small subnets.

84.   What is RAID?

A method for providing fault tolerance by using multiple hard disk drives.

85.   85. What is passive topology?

When the computers on the network simply listen and receive the signal, they are referred to as passive because they don't amplify the signal in any way. Example for passive topology -linear bus.

86.   What is Brouter?

Hybrid devices that combine the features of both bridges and routers.

87.   What is cladding?

A layer of a glass surrounding the center fiber of glass inside a fiber-optic cable.

88.   What is point-to-point protocol?

A communications protocol used to connect computers to remote networking services including Internet service providers.

89.   How Gateway is different from Routers?

A gateway operates at the upper levels of the OSI model and translates information between two completely different network architectures or data formats.

90.   What is attenuation?

The degeneration of a signal over distance on a network cable is called attenuation.

91.   91. What is MAC address?

The address for a device as it is identified at the Media Access Control (MAC) layer in the network architecture. MAC address is usually stored in ROM on the network adapter card and is unique.

92.   Difference between bit rate and baud rate.

Bit rate is the number of bits transmitted during one second whereas baud rate refers to the number of signal units per second that are required to represent those bits.
  baud rate = (bit rate / N)
  where N is no-of-bits represented by each signal shift.

93.   What is Bandwidth?

Every line has an upper limit and a lower limit on the frequency of signals it can carry. This limited range is called the bandwidth.

94.   What are the types of Transmission media?

Signals are usually transmitted over some transmission media that are broadly classified in to two categories.

a.) Guided Media: These are those that provide a conduit from one device to another that include twisted-pair, coaxial cable and fiber-optic cable. A signal traveling along any of these media is directed and is contained by the physical limits of the medium. Twisted-pair and coaxial cable use metallic that accept and transport signals in the form of electrical current. Optical fiber is a glass or plastic cable that accepts and transports signals in the form of light.

b.) Unguided Media: This is the wireless media that transport electromagnetic waves without using a physical conductor. Signals are broadcast either through air. This is done through radio communication, satellite communication and cellular telephony.

95.   What is Project 802?

It is a project started by IEEE to set standards to enable intercommunication between equipment from a variety of manufacturers. It is a way for specifying functions of the physical layer, the data link layer and to some extent the network layer to allow for interconnectivity of major LAN protocols.

It consists of the following:

1.       802.1 is an internetworking standard for compatibility of different LANs and MANs across protocols.

2.       802.2 Logical link control (LLC) is the upper sublayer of the data link layer which is non-architecture-specific, that is remains the same for all IEEE-defined LANs.

3.       Media access control (MAC) is the lower sublayer of the data link layer that contains some distinct modules each carrying proprietary information specific to the LAN product being used. The modules are Ethernet LAN (802.3), Token ring LAN (802.4), Token bus LAN (802.5).

4.       802.6 is distributed queue dual bus (DQDB) designed to be used in MANs.

96.   What is Protocol Data Unit?

The data unit in the LLC level is called the protocol data unit (PDU). The PDU contains of four fields a destination service access point (DSAP), a source service access point (SSAP), a control field and an information field. DSAP, SSAP are addresses used by the LLC to identify the protocol stacks on the receiving and sending machines that are generating and using the data. The control field specifies whether the PDU frame is a information frame (I - frame) or a supervisory frame (S - frame) or a unnumbered frame (U - frame).

97.   97. What are the different type of networking / internetworking devices?

1.       Repeater: Also called a regenerator, it is an electronic device that operates only at physical layer. It receives the signal in the network before it becomes weak, regenerates the original bit pattern and puts the refreshed copy back in to the link.

2.       Bridges: These operate both in the physical and data link layers of LANs of same type. They divide a larger network in to smaller segments. They contain logic that allow them to keep the traffic for each segment separate and thus are repeaters that relay a frame only the side of the segment containing the intended recipent and control congestion.

3.       Routers: They relay packets among multiple interconnected networks (i.e. LANs of different type). They operate in the physical, data link and network layers. They contain software that enable them to determine which of the several possible paths is the best for a particular transmission.

4.       Gateways: They relay packets among networks that have different protocols (e.g. between a LAN and a WAN). They accept a packet formatted for one protocol and convert it to a packet formatted for another protocol before forwarding it. They operate in all seven layers of the OSI model.

98.   What is ICMP?

ICMP is Internet Control Message Protocol, a network layer protocol of the TCP/IP suite used by hosts and gateways to send notification of datagram problems back to the sender. It uses the echo test / reply to test whether a destination is reachable and responding. It also handles both control and error messages.

99.   What are the data units at different layers of the TCP / IP protocol suite?

The data unit created at the application layer is called a message, at the transport layer the data unit created is called either a segment or an user datagram, at the network layer the data unit created is called the datagram, at the data link layer the datagram is encapsulated in to a frame and finally transmitted as signals along the transmission media.

100.                       What is difference between ARP and RARP?

The address resolution protocol (ARP) is used to associate the 32 bit IP address with the 48 bit physical address, used by a host or a router to find the physical address of another host on its network by sending a ARP query packet that includes the IP address of the receiver.

The reverse address resolution protocol (RARP) allows a host to discover its Internet address when it knows only its physical address.

101.                       What is the minimum and maximum length of the header in the TCP segment and IP datagram?

The header should have a minimum length of 20 bytes and can have a maximum length of 60 bytes.

102.                       What is the range of addresses in the classes of internet addresses?

Class A   -       0.0.0.0   -   127.255.255.255
Class B   -   128.0.0.0   -   191.255.255.255
Class C   -   192.0.0.0   -   223.255.255.255
Class D   -   224.0.0.0   -   239.255.255.255
Class E   -   240.0.0.0   -   255.255.255.255

103.                       103. What is the difference between TFTP and FTP application layer protocols?

The Trivial File Transfer Protocol (TFTP) allows a local host to obtain files from a remote host but does not provide reliability or security. It uses the fundamental packet delivery services offered by UDP.

The File Transfer Protocol (FTP) is the standard mechanism provided by TCP / IP for copying a file from one host to another. It uses the services offer by TCP and so is reliable and secure. It establishes two connections (virtual circuits) between the hosts, one for data transfer and another for control information.

104.                       What are major types of networks and explain?

1.       Server-based network: provide centralized control of network resources and rely on server computers to provide security and network administration

2.       Peer-to-peer network: computers can act as both servers sharing resources and as clients using the resources.

105.                       What are the important topologies for networks?

1.       BUS topology: In this each computer is directly connected to primary network cable in a single line.
Advantages: Inexpensive, easy to install, simple to understand, easy to extend.

2.       STAR topology: In this all computers are connected using a central hub.
Advantages: Can be inexpensive, easy to install and reconfigure and easy to trouble shoot physical problems.

3.       RING topology: In this all computers are connected in loop. Advantages: All computers have equal access to network media, installation can be simple, and signal does not degrade as much as in other topologies because each computer regenerates it.

106.                       What is mesh network?

A network in which there are multiple network links between computers to provide multiple paths for data to travel.

107.                       What is difference between baseband and broadband transmission?

In a baseband transmission, the entire bandwidth of the cable is consumed by a single signal. In broadband transmission, signals are sent on multiple frequencies, allowing multiple signals to be sent simultaneously.

108.                       Explain 5-4-3 rule?

In a Ethernet network, between any two points on the network ,there can be no more than five network segments or four repeaters, and of those five segments only three of segments can be populated.

109.                       109. What MAU?

In token Ring , hub is called Multistation Access Unit(MAU).

110.                       What is the difference between routable and non- routable protocols?

Routable protocols can work with a router and can be used to build large networks. Non-Routable protocols are designed to work on small, local networks and cannot be used with a router.

111.                       Why should you care about the OSI Reference Model?

It provides a framework for discussing network operations and design.

112.                       What is logical link control?

One of two sublayers of the data link layer of OSI reference model, as defined by the IEEE 802 standard. This sublayer is responsible for maintaining the link between computers when they are sending data across the physical network connection.

113.                       What is virtual channel?

Virtual channel is normally a connection from one source to one destination, although multicast connections are also permitted. The other name for virtual channel is virtual circuit.

114.                       What is virtual path?

Along any transmission path from a given source to a given destination, a group of virtual circuits can be grouped together into what is called path.

115.                       115. What is packet filter?

Packet filter is a standard router equipped with some extra functionality. The extra functionality allows every incoming or outgoing packet to be inspected. Packets meeting some criterion are forwarded normally. Those that fail the test are dropped.

116.                       What is traffic shaping?

One of the main causes of congestion is that traffic is often busy. If hosts could be made to transmit at a uniform rate, congestion would be less common. Another open loop method to help manage congestion is forcing the packet to be transmitted at a more predictable rate. This is called traffic shaping.

117.                       What is multicast routing?

Sending a message to a group is called multicasting, and its routing algorithm is called multicast routing.

118.                       What is region?

When hierarchical routing is used, the routers are divided into what we will call regions, with each router knowing all the details about how to route packets to destinations within its own region, but knowing nothing about the internal structure of other regions.

119.                       What is silly window syndrome?

It is a problem that can ruin TCP performance. This problem occurs when data are passed to the sending TCP entity in large blocks, but an interactive application on the receiving side reads 1 byte at a time.

120.                       What are Digrams and Trigrams?

The most common two letter combinations are called as digrams. e.g. th, in, er, re and an. The most common three letter combinations are called as trigrams. e.g. the, ing, and, and ion.

121.                       121. Expand IDEA.

IDEA stands for International Data Encryption Algorithm.

122.                       What is wide-mouth frog?

Wide-mouth frog is the simplest known key distribution center (KDC) authentication protocol.

123.                       What is Mail Gateway?

It is a system that performs a protocol translation between different electronic mail delivery protocols.

124.                       What is IGP (Interior Gateway Protocol)?

It is any routing protocol used within an autonomous system.

125.                       What is EGP (Exterior Gateway Protocol)?

It is the protocol the routers in neighboring autonomous systems use to identify the set of networks that can be reached within or via each autonomous system.

126.                       What is autonomous system?

It is a collection of routers under the control of a single administrative authority and that uses a common Interior Gateway Protocol.

127.                       127. What is BGP (Border Gateway Protocol)?

It is a protocol used to advertise the set of networks that can be reached with in an autonomous system. BGP enables this information to be shared with the autonomous system. This is newer than EGP (Exterior Gateway Protocol).

128.                       What is Gateway-to-Gateway protocol?

It is a protocol formerly used to exchange routing information between Internet core routers.

129.                       What is NVT (Network Virtual Terminal)?

It is a set of rules defining a very simple virtual terminal interaction. The NVT is used in the start of a Telnet session.

130.                       What is a Multi-homed Host?

It is a host that has a multiple network interfaces and that requires multiple IP addresses is called as a Multi-homed Host.

131.                       What is Kerberos?

It is an authentication service developed at the Massachusetts Institute of Technology. Kerberos uses encryption to prevent intruders from discovering passwords and gaining unauthorized access to files.

132.                       What is OSPF?

It is an Internet routing protocol that scales well, can route traffic along multiple paths, and uses knowledge of an Internet's topology to make accurate routing decisions

133.                       133. What is Proxy ARP?

It is using a router to answer ARP requests. This will be done when the originating host believes that a destination is local, when in fact is lies beyond router.

134.                       What is SLIP (Serial Line Interface Protocol)?

It is a very simple protocol used for transmission of IP datagrams across a serial line.

135.                       What is RIP (Routing Information Protocol)?

It is a simple protocol used to exchange information between the routers.

136.                       What is source route?

It is a sequence of IP addresses identifying the route a datagram must follow. A source route may optionally be included in an IP datagram header.

Operating Systems Related Questions

1.       Explain the concept of Reentrancy?

It is a useful, memory-saving technique for multiprogrammed timesharing systems. A Reentrant Procedure is one in which multiple users can share a single copy of a program during the same period. Reentrancy has 2 key aspects: The program code cannot modify itself, and the local data for each user process must be stored separately. Thus, the permanent part is the code, and the temporary part is the pointer back to the calling program and local variables used by that program. Each execution instance is called activation. It executes the code in the permanent part, but has its own copy of local variables/parameters. The temporary part associated with each activation is the activation record. Generally, the activation record is kept on the stack.
Note: A reentrant procedure can be interrupted and called by an interrupting program, and still execute correctly on returning to the procedure.

2.       Explain Belady's Anomaly?

Also called FIFO anomaly. Usually, on increasing the number of frames allocated to a process virtual memory, the process execution is faster, because fewer page faults occur. Sometimes, the reverse happens, i.e., the execution time increases even when more frames are allocated to the process. This is Belady's Anomaly. This is true for certain page reference patterns.

3.       What is a binary semaphore? What is its use?

A binary semaphore is one, which takes only 0 and 1 as values. They are used to implement mutual exclusion and synchronize concurrent processes.

4.       What is thrashing?

It is a phenomenon in virtual memory schemes when the processor spends most of its time swapping pages, rather than executing instructions. This is due to an inordinate number of page faults.

5.       List the Coffman's conditions that lead to a deadlock.

1.       Mutual Exclusion: Only one process may use a critical resource at a time.

2.       Hold & Wait: A process may be allocated some resources while waiting for others.

3.       No Pre-emption: No resource can be forcible removed from a process holding it.

4.       Circular Wait: A closed chain of processes exist such that each process holds at least one resource needed by another process in the chain.

6.       What are short, long and medium-term scheduling?

Long term scheduler determines which programs are admitted to the system for processing. It controls the degree of multiprogramming. Once admitted, a job becomes a process.

Medium term scheduling is part of the swapping function. This relates to processes that are in a blocked or suspended state. They are swapped out of real-memory until they are ready to execute. The swapping-in decision is based on memory-management criteria.

Short term scheduler, also know as a dispatcher executes most frequently, and makes the finest-grained decision of which process should execute next. This scheduler is invoked whenever an event occurs. It may lead to interruption of one process by preemption.

7.       What are turnaround time and response time?

Turnaround time is the interval between the submission of a job and its completion. Response time is the interval between submission of a request, and the first response to that request.

8.       What are the typical elements of a process image?

User data: Modifiable part of user space. May include program data, user stack area, and programs that may be modified.

User program: The instructions to be executed.

System Stack: Each process has one or more LIFO stacks associated with it. Used to store parameters and calling addresses for procedure and system calls.

Process control Block (PCB): Info needed by the OS to control processes.

9.       What is the Translation Lookaside Buffer (TLB)?

In a cached system, the base addresses of the last few referenced pages is maintained in registers called the TLB that aids in faster lookup. TLB contains those page-table entries that have been most recently used. Normally, each virtual memory reference causes 2 physical memory accesses- one to fetch appropriate page-table entry, and one to fetch the desired data. Using TLB in-between, this is reduced to just one physical memory access in cases of TLB-hit.

10.   What is the resident set and working set of a process?

Resident set is that portion of the process image that is actually in real-memory at a particular instant. Working set is that subset of resident set that is actually needed for execution. (Relate this to the variable-window size method for swapping techniques.)

11.   When is a system in safe state?

The set of dispatchable processes is in a safe state if there exists at least one temporal order in which all processes can be run to completion without resulting in a deadlock.

12.   What is cycle stealing?

We encounter cycle stealing in the context of Direct Memory Access (DMA). Either the DMA controller can use the data bus when the CPU does not need it, or it may force the CPU to temporarily suspend operation. The latter technique is called cycle stealing. Note that cycle stealing can be done only at specific break points in an instruction cycle.

13.   What is meant by arm-stickiness?

If one or a few processes have a high access rate to data on one track of a storage disk, then they may monopolize the device by repeated requests to that track. This generally happens with most common device scheduling algorithms (LIFO, SSTF, C-SCAN, etc). High-density multisurface disks are more likely to be affected by this than low density ones.

14.   What are the stipulations of C2 level security?

C2 level security provides for:

1.       Discretionary Access Control

2.       Identification and Authentication

3.       Auditing

4.       Resource reuse

15.   What is busy waiting?

The repeated execution of a loop of code while waiting for an event to occur is called busy-waiting. The CPU is not engaged in any real productive activity during this period, and the process does not progress toward completion.

16.   Explain the popular multiprocessor thread-scheduling strategies.

1.       Load Sharing: Processes are not assigned to a particular processor. A global queue of threads is maintained. Each processor, when idle, selects a thread from this queue. Note that load balancing refers to a scheme where work is allocated to processors on a more permanent basis.

2.       Gang Scheduling: A set of related threads is scheduled to run on a set of processors at the same time, on a 1-to-1 basis. Closely related threads / processes may be scheduled this way to reduce synchronization blocking, and minimize process switching. Group scheduling predated this strategy.

3.       Dedicated processor assignment: Provides implicit scheduling defined by assignment of threads to processors. For the duration of program execution, each program is allocated a set of processors equal in number to the number of threads in the program. Processors are chosen from the available pool.

4.       Dynamic scheduling: The number of thread in a program can be altered during the course of execution.

17.   When does the condition 'rendezvous' arise?

In message passing, it is the condition in which, both, the sender and receiver are blocked until the message is delivered.

18.   What is a trap and trapdoor?

Trapdoor is a secret undocumented entry point into a program used to grant access without normal methods of access authentication. A trap is a software interrupt, usually the result of an error condition

19.   What are local and global page replacements?

Local replacement means that an incoming page is brought in only to the relevant process address space. Global replacement policy allows any page frame from any process to be replaced. The latter is applicable to variable partitions model only.

20.   Define latency, transfer and seek time with respect to disk I/O.

Seek time is the time required to move the disk arm to the required track. Rotational delay or latency is the time it takes for the beginning of the required sector to reach the head. Sum of seek time (if any) and latency is the access time. Time taken to actually transfer a span of data is transfer time.

21.   Describe the Buddy system of memory allocation.

Free memory is maintained in linked lists, each of equal sized blocks. Any such block is of size 2^k. When some memory is required by a process, the block size of next higher order is chosen, and broken into two. Note that the two such pieces differ in address only in their kth bit. Such pieces are called buddies. When any used block is freed, the OS checks to see if its buddy is also free. If so, it is rejoined, and put into the original free-block linked-list.

22.   What is time-stamping?

It is a technique proposed by Lamport, used to order events in a distributed system without the use of clocks. This scheme is intended to order events consisting of the transmission of messages. Each system 'i' in the network maintains a counter Ci. Every time a system transmits a message, it increments its counter by 1 and attaches the time-stamp Ti to the message. When a message is received, the receiving system 'j' sets its counter Cj to 1 more than the maximum of its current value and the incoming time-stamp Ti. At each site, the ordering of messages is determined by the following rules: For messages x from site i and y from site j, x precedes y if one of the following conditions holds....(a) if Ti<Tj or (b) if Ti=Tj and i<j.

23.   How are the wait/signal operations for monitor different from those for semaphores?

If a process in a monitor signal and no task is waiting on the condition variable, the signal is lost. So this allows easier program design. Whereas in semaphores, every operation affects the value of the semaphore, so the wait and signal operations should be perfectly balanced in the program.

24.   In the context of memory management, what are placement and replacement algorithms?

Placement algorithms determine where in available real-memory to load a program. Common methods are first-fit, next-fit, best-fit. Replacement algorithms are used when memory is full, and one process (or part of a process) needs to be swapped out to accommodate a new program. The replacement algorithm determines which are the partitions to be swapped out.

25.   In loading programs into memory, what is the difference between load-time dynamic linking and run-time dynamic linking?

For load-time dynamic linking: Load module to be loaded is read into memory. Any reference to a target external module causes that module to be loaded and the references are updated to a relative address from the start base address of the application module.

With run-time dynamic loading: Some of the linking is postponed until actual reference during execution. Then the correct module is loaded and linked.

26.   What are demand-paging and pre-paging?

With demand paging, a page is brought into memory only when a location on that page is actually referenced during execution. With pre-paging, pages other than the one demanded by a page fault are brought in. The selection of such pages is done based on common access patterns, especially for secondary memory devices.

27.   Paging a memory management function, while multiprogramming a processor management function, are the two interdependent?

Yes.

28.   What is page cannibalizing?

Page swapping or page replacements are called page cannibalizing.

29.   What has triggered the need for multitasking in PCs?

1.       Increased speed and memory capacity of microprocessors together with the support fir virtual memory and

2.       Growth of client server computing

30.   What are the four layers that Windows NT have in order to achieve independence?

1.       Hardware abstraction layer

2.       Kernel

3.       Subsystems

4.       System Services.

31.   What is SMP?

To achieve maximum efficiency and reliability a mode of operation known as symmetric multiprocessing is used. In essence, with SMP any process or threads can be assigned to any processor.

32. What are the key object oriented concepts used by Windows NT?

Encapsulation, Object class and instance.

33. Is Windows NT a full blown object oriented operating system? Give reasons.

No Windows NT is not so, because its not implemented in object oriented language and the data structures reside within one executive component and are not represented as objects and it does not support object oriented capabilities.

34. What is a drawback of MVT?

It does not have the features like

1. ability to support multiple processors
2. virtual storage
3. source level debugging
34. What is process spawning?

When the OS at the explicit request of another process creates a process, this action is called process spawning.

36. How many jobs can be run concurrently on MVT?

15 jobs.

37.   List out some reasons for process termination.

1.       Normal completion

2.       Time limit exceeded

3.       Memory unavailable

4.       Bounds violation

5.       Protection error

6.       Arithmetic error

7.       Time overrun

8.       I/O failure

9.       Invalid instruction

10.   Privileged instruction

11.   Data misuse

12.   Operator or OS intervention

13.   Parent termination.

38.   What are the reasons for process suspension?

1.       swapping

2.       interactive user request

3.       timing

4.       parent process request

39.   What is process migration?

It is the transfer of sufficient amount of the state of process from one machine to the target machine.

40.   What is mutant?

In Windows NT a mutant provides kernel mode or user mode mutual exclusion with the notion of ownership.

41.   What is an idle thread?

The special thread a dispatcher will execute when no ready thread is found.

42.   What is FtDisk?

It is a fault tolerance disk driver for Windows NT.

43.   What are the possible threads a thread can have?

1.       Ready

2.       Standby

3.       Running

4.       Waiting

5.       Transition

6.       Terminated

44.   What are rings in Windows NT?

Windows NT uses protection mechanism called rings provides by the process to implement separation between the user mode and kernel mode.

45.   What is Executive in Windows NT?

In Windows NT, executive refers to the operating system code that runs in kernel mode.

46.   What are the sub-components of I/O manager in Windows NT?

1.       Network redirector/ Server

2.       Cache manager.

3.       File systems

4.       Network driver

5.       Device driver

47.   What are DDks? Name an operating system that includes this feature.

DDks are device driver kits, which are equivalent to SDKs for writing device drivers. Windows NT includes DDks.

48.   What level of security does Windows NT meets?

C2 level security.