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Interview Questions and Answers for 'Web' - 362 question(s) found - Order By Newest

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Very frequently asked. Among first few questions in almost all interviews. Among Top 5 frequently asked questions. Frequently asked in Indian service companies (HCL,TCS,Infosys,Capgemini etc based on multiple feedback )
  Q1. Difference between == and .equals() ?Core Java
Anonymous
Ans. "equals" is the method of object class which is supposed to be overridden to check object equality, whereas "==" operator evaluate to see if the object handlers on the left and right are pointing to the same object in memory.

x.equals(y) means the references x and y are holding objects that are equal. x==y means that the references x and y have same object.

Sample code:

String x = new String("str");
String y = new String("str");

System.out.println(x == y); // prints false
System.out.println(x.equals(y)); // prints true

  Sample Code for equals

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   Like         Discuss         Correct / Improve     java   string comparison   string   object class   ==    equals   object equality  operator     Asked in 289 Companies      basic        frequent

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Very frequently asked. Favorite question in Walk in Drive of many Indian service companies. Frequently asked in HCL Technologies, TCS and Accenture.
  Q2. What is the difference between final, finally and finalize() ?Core Java
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Ans. final - constant variable, objects cannot be de-referenced, restricting method overriding, restricting class sub classing.

finally - handles exception. The finally block is optional and provides a mechanism to clean up regardless of what happens within the try block. Use the finally block to close files or to release other system resources like database connections, statements etc.

finalize() - method helps in garbage collection. A method that is invoked before an object is discarded by the garbage collector, allowing it to clean up its state.

  Sample Code for final

  Sample Code for finally

  Sample Code for finalize

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   Like         Discuss         Correct / Improve     java   oops   final   finally   finalize     Asked in 60 Companies      basic        frequent

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  Q3. Explain OOPs

or

Explain OOPs Principles

or

Explain OOPs Concepts

or

Explain OOPs features

or

Tell me something about OOPs
Core Java2017-06-13 08:25:45

Ans. OOPs or Object Oriented Programming is a Programming model which is organized around Objects instead of processes. Instead of a process calling series of processes, this model stresses on communication between objects. Objects that all self sustained, provide security by encapsulating it's members and providing abstracted interfaces over the functions it performs. OOP's facilitate the following features

1. Inheritance for Code Reuse
2. Abstraction for modularity, maintenance and agility
3. Encapsulation for security and protection
4. Polymorphism for flexibility and interfacing

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   Like         Discuss         Correct / Improve     oops  oops features     Asked in 237 Companies      basic        frequent


Recently asked in TCS , Tech Mahindra, HCL , Accenture and Fidelity.
  Q4. Explain Flow of Spring MVC ?Spring
Admin
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Ans. The DispatcherServlet configured in web.xml file receives the request.

The DispatcherServlet finds the appropriate Controller with the help of HandlerMapping and then invokes associated Controller.

Then the Controller executes the logic business logic and then returns ModeAndView object to the DispatcherServlet.

The DispatcherServlet determines the view from the ModelAndView object.

Then the DispatcherServlet passes the model object to the View.

The View is rendered and the Dispatcher Servlet sends the output to the Servlet container.

Finally Servlet Container sends the result back to the user.

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   Like         Discuss         Correct / Improve     j2ee   spring   mvc   frameworks   web applications   architecture     Asked in 10 Companies      Basic        frequent


 Q5. What is session tracking and how do you track a user session in servlets?Java EE
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Ans. Session tracking is a mechanism that servlets use to maintain state about a series requests from the same user across some period of time. The methods used for session tracking are:

User Authentication - occurs when a web server restricts access to some of its resources to only those clients that log in using a recognized username and password

Hidden form fields - fields are added to an HTML form that are not displayed in the client's browser. When the form containing the fields is submitted, the fields are sent back to the server

URL rewriting - every URL that the user clicks on is dynamically modified or rewritten to include extra information. The extra information can be in the form of extra path information, added parameters or some custom, server-specific URL change.

Cookies - a bit of information that is sent by a web server to a browser and which can later be read back from that browser.

HttpSession- places a limit on the number of sessions that can exist in memory.

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   Like         Discuss         Correct / Improve     j2ee   servlets   session   session management   web applications   cookies   httpsession   url rewriting   architecture     Asked in 1 Companies


Very frequently asked in companies using SOA.
  Q6. What are RESTful Web Services ?Rest
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Ans. REST or Representational State Transfer is a flexible architecture style for creating web services that recommends the following guidelines -

1. http for client server communication,
2. XML / JSON as formatiing language ,
3. Simple URI as address for the services and,
4. stateless communication.

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   Like         Discuss         Correct / Improve     java   web services   rest   java   j2ee  architecture     Asked in 14 Companies      intermediate        frequent


Frequently asked. Among first few questions in the J2EE segment of interview.
  Q7. What is deployment descriptor ?

or

What is the use of deployment descriptor ?
Java EE2016-06-04 22:46:40

Ans. Deployment Descriptor which is usually web.xml is used to specify the classes, resources and configuration of the application and how the web server uses them to serve web requests.This file is usually added to WEB-INF folder and contains following

* Servlet entries and url mapping
* Plugins
* Some info regarding authentication / filters
* Landing Page
* Event Handlers

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   Like         Discuss         Correct / Improve     web.xml   servlets  deployment descriptor     Asked in 15 Companies      basic        frequent

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 Q8. What are wrapper classes ?Core Java
Anonymous
Ans. They are wrappers to primitive data types. They allow us to access primitives as objects.

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   Like         Discuss         Correct / Improve     java   data types   wrapper classes     Asked in 3 Companies      basic        frequent


Very frequently asked.Usually among first few questions.
  Q9. What is MVC ? Design
Anonymous
Ans. MVC is a Design Pattern that facilititates loose coupling by segregating responsibilities in a Web application

1. Controller receives the requests and handles overall control of the request
2. Model holds majority of the Business logic, and
3. View comprise of the view objects and GUI component

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  Q10. Difference between GET and POST Requests ?Web Service2016-07-22 15:00:21

Ans. GET is supposed to get information from the server. Client sends the minimal information so that Server can respond with the response body on basis of request. For example - You want to get complete employment record for employee id 123

POST is supposed to send the information for submission. Payload or a Body is usually sent so that it can be persisted on the server. For example - Sending the complete information of an employee ( id, name , dept etc ) to the server for persisting it.

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   Like         Discuss         Correct / Improve     get vs post   web service   rest     Asked in 11 Companies      basic        frequent


 Q11. What is the relationship between VPC and subnet ? Can you tell with an example ?Networking2019-01-27 21:19:19

Ans. A VPC is devided into multiple subnets. Subnet in a particular VPC could be public or private.

For Example - A particular account may have multiple vpc's for each of the business type. For each Business or VPC , One can have different subnets to cater to each department so that access across departments could be restricted. But still there could be identities that have control over different subnets. Moreover we could have multiple subnets for each department so as to have distinguished public and private networks having different types of applications ( public facing or internal consumption )

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   Like         Discuss         Correct / Improve     aws vpc  aws subnet  subnet  vpc  Amazon Web Services (AWS)


 Q12. Is tomcat an application or Web server ?Server
Anonymous
Ans. Tomcat is a web server and a Servlet container. It is often used as an application server for web-based applications but does not include the complete suite of capabilities that a Java EE application server would supply.

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   Like         Discuss         Correct / Improve     tomcat   j2ee   web server   application server   build management


 Q13. Is Apache an application or Web server ?
Anonymous
Ans. Web server.

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   Like         Discuss         Correct / Improve     apache   web server   j2ee


 Q14. What is meant by an "asynchronous event." Give some examples ?Operating System
Anonymous
Ans. An asynchronous event is one that occurs at an unpredictable time outside the control of the program that the CPU is running. It is not "synchronized" with the program.

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 Q15. Can we have multiple servlets in a web application and How can we do that ?Java EE
Anonymous
Ans. Yes by making entries in web.xml

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 Q16. How can we manage Error Messages in the web application ?Solution
Anonymous
Ans. Within message.properties file.

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 Q17. What bean scopes does Spring support? Explain them.Spring
Admin
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Ans. The Spring Framework supports following five scopes -

Singleton
prototype
request
session
global-session

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 Q18. What are different types of cookies ?Java EE
Admin
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Ans. Session cookies , which are deleted once the session is over.

Permanent cookies , which stays at client PC even if the session is disconnected.

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   Like         Discuss         Correct / Improve     j2ee   servlets   session   session management   web applications   cookies   httpsession


 Q19. How to access a Web Element if there are many elements with the same XPath ?
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Ans. By specifying the Index like

//button[@class='button'])[2]

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 Q20. In which cases using SOAP is preferred over REST ?Web Service2017-04-27 18:08:18

Ans. SOAP services are better in case we need to establish a formal and detail contract with the client or callers and hence suitable for

1. Services published for much wider unknown audience
2. Require large input payload
3. Requiring different level for authentication

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   Like         Discuss         Correct / Improve     soap vs rest  soap  rest     Asked in 2 Companies


 Q21. What are the services provided by AWS ?Amazon Web Services (AWS)2018-01-11 10:57:06

Ans. AWS provides various types of services like Computing ( EC2 , Lambda , EKS ), Storage ( S3, Glacier ), Database ( RDS , DynamoDB ), Streaming ( Kinesis ), Queue ( SQS ), Security and Access ( IAM ) etc.

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 Q22. What are the problems one could face while working with serverless technologies like AWS Lambda ?Amazon Web Services (AWS)2018-01-30 18:05:47

Ans. Warm up time for certain technologies like Java ( JVM Warmup )

Performance

Size of Deployable ( Bigger size packaging should go in S3 )

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   Like         Discuss         Correct / Improve     serverless technologies  aws lambda  aws serverless computing  amazon cloud serverless computing  amazon lambda     Asked in 1 Companies


 Q23. Describe structure of a Web application.architecture2018-07-04 16:18:26

Ans. WEB APP |WEB-INF - META-INF | | | META-INF.MF | lib - WEB.xml - Classes

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   Like         Discuss         Correct / Improve     web application     Asked in 3 Companies      intermediate        frequent


 Q24. What would you do if you see an error thrown by a lambda function as "Access Denied" while doing something with S3 ?Amazon Web Services (AWS)2018-10-26 11:34:47

Ans. Just like people , AWS resources too have execution roles or permissions. Seems like in such a situation Lambda function may not have sufficient privileges to perform operations on S3. For example - The execution role of Lambda may just have read permissions on S3 and we may be trying to perform PutObject operation.

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   Like         Discuss         Correct / Improve     aws s3  aws storage  amazon cloud storage  amazon s3  aws lambda  aws serverless computing  amazon cloud serverless computing  amazon lambda


 Q25. What is the cost of using Cloud Formation ?Amazon Web Services (AWS)2019-01-08 15:53:06

Ans. Cloud Formation does not have any additional cost but you are charged for the underlying resources it builds.

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 Q26. What is the use of Amazon Glacier?Amazon Web Services (AWS)2019-01-08 16:11:47

Ans. Its a storage option provided by AWS which is even cheaper than S3. As the objects are archieved before saving, retrieval time is pretty bad.

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 Q27. Design an e commerce application using AWS ? What AWS services will you use ?Amazon Web Services (AWS)2019-01-08 16:24:47

Ans. CloudFront for Static Media and cached content
EC2 and EKS ( Docker ) for main application computing
RDS and DynamoDB for Database
Lambda ( computing ) for running back end cron jobs
Kinesis for streaming and SQS for queuing
CloudWatch for Monitoring
CloudFormation for Infrastructure templating
S3 for Object Storage

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 Q28. Difference between AWS Cloud Formation and AWS AMI ?Amazon Web Services (AWS)2019-01-11 13:40:03

Ans. AMI is an Amazon Machine Image. It contains the configuration to enable to boot up an EC2 instance with said configuration whereas Cloud formation is a templating language that allows to describe how to build a VPC and also allows you to create AWS services

AMI is templating specific to instances whereas the scope of CloudFormation templating is much bigger. CloudFormation could use AMI for launching instances along with other services.

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 Q29. What does AMI include ?Amazon Web Services (AWS)2019-01-11 13:42:29

Ans. A template for the instance.

Launch permission decisions

A block device mapping, when an instance is launched it determines the volumes to attach to that instances.


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 Q30. Why is cloud infrastructure so powerful ?Cloud Computing2019-01-14 10:52:40

Ans. Because it gives the ability to provision infrastructure on Demand with No contracts and strings attached.

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   Like         Discuss         Correct / Improve     Amazon Web Service (AWS)


 Q31. Which region is the latest and most popular in AWS ? What are the advantages and disadvantages of using this region ?Amazon Web Services (AWS)2019-01-14 10:56:40

Ans. US-East Virginia

This is the oldest and most popular region. All new features are rolled first in this region and hence they are first available there. The downside is that because of experimentation with new services, unavailability time is quite high.

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   Like         Discuss         Correct / Improve     aws region  aws us-east-1


 Q32. Difference between Region , Availability zone and Edge Locations ?Amazon Web Services (AWS)2019-01-14 10:57:57

Ans. A Region is a Geographical entity like US-East , US-West etc. Each Region may have multiple availability zones where each zone comprise of 1 or more Data Center located with each other.

Edge Locations are the sites that hosts cached content for faster delivery and for saving network traffic as they feed content from sites that are local or near to consumption.

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   Like         Discuss         Correct / Improve     aws region  aws availability zone  aws edge location  region vs availabillity zone


 Q33. What are the advantage of having Edge Locations ?Amazon Web Services (AWS)2019-01-14 11:00:06

Ans. It saves Network traffic and facilitates faster delivery by hosting bulk media and cached data near to client.

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 Q34. What does effect , action and resource means with respect to AWS IAM policy ?Amazon Web Services (AWS)2019-01-14 13:51:23

Ans. effect means whether the effect of this Policy is to allow or deny, action means the type of action ( read , write ) and service, and resource is the resource where this should apply.

For example - If we want to have a Policy of providing read access on S3 ,
effect will be "allow"
action will be "s3:GetObject"
resource will be "arn:aws:s3:::examplebucket/*"

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   Like         Discuss         Correct / Improve     aws iam  amazon iam


 Q35. Within AWS S3, Why new files are available immediately for read operation but not the updates ? Amazon Web Services (AWS)2019-01-14 14:08:59

Ans. Because new files will be fed from where ever they are first available but AWS have no way to identify which is the most updated version among the various regions. The updated version can only be assured once the replication to all availability zones is complete.

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 Q36. What are the different S3 storage Tiers ?Amazon Web Services (AWS)2019-01-14 14:16:05

Ans. S3 Standard
S3 IA - Infrequently Accessed
S3 One Zone IA - One Zone only , Infrequently Accessed
S3 Glacier - achieved

S3 Standard is most expensive , Glacier is least expensive

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 Q37. What are the factors on which customers are charged for using S3 ?Amazon Web Services (AWS)2019-01-14 14:51:36

Ans. Storage Tier ( IA , Standard , Glacier etc )
Storage ( Volume of Data )
No of Requests
Meta Data
Data Transfer Speed acceleration through cache and Edge Location

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 Q38. What kind of Access Policy should be kept on S3 Buckets and Policy ?Amazon Web Services (AWS)2019-01-15 11:49:49

Ans. We should only allow access that's needed. So the security Policy should be as restrictive as possible.

Buckets and Files should never be made public unless until they are needed it to be like that.

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 Q39. How can we protect from accidental deletes in S3 ?Amazon Web Services (AWS)2019-01-15 11:55:33

Ans. Versioning ( will create Delete marker )
MFA Delete ( authentication upon deletion )
Cross Region Replication ( Replicates aren't deleted )

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 Q40. How can we restrict CloudFront access to a particular Geography ?Amazon Web Services (AWS)2019-01-15 12:07:20

Ans. We can select the appropriate Price Class if that suits us.

We can do Geo Targeting by black listing / white listing certain geographies.

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   Like         Discuss         Correct / Improve     aws cloudfront  amazon cloudfront


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