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Interview Questions and Answers for 'Aws' - 307 question(s) found - Order By Newest | ||||
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 ) and Epam Systems | ||||
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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   == vs equals   equals vs == Asked in 294 Companies basic   frequent | ||||
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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 260 Companies basic   frequent | ||||
Frequently asked at Manhattan Associates ( Based on 2 feedback ) | ||||
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Ans. Its an anonymous method without any declaration. Lambda Expression are useful to write shorthand Code and hence saves the effort of writing lengthy Code. It promotes Developer productivity, Better Readable and Reliable code. | ||||
Sample Code for lambda | ||||
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Like Discuss Correct / Improve  java   java8   lambda expression   architecture Asked in 58 Companies expert   frequent | ||||
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Frequently asked question in companies using Hibernate. | ||||
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Ans. It's a feature to lazily initialize dependencies , relationship and associations from the Database. Any related references marked as @OneToMany or @ManyToMany are loaded lazily i.e when they are accessed and not when the parent is loaded. | ||||
Sample Code for Lazy Initialization | ||||
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Like Discuss Correct / Improve  hibernate   lazy loading hibernate   lazy initialization hibernate   architecture Asked in 77 Companies Basic   frequent | ||||
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Basic and Very Frequently asked. | ||||
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Ans. Polymorphism means the condition of occurring in several different forms. Polymorphism in Java is achieved in two manners 1. Static polymorphism is the polymorphic resolution identified at compile time and is achieved through function overloading whereas 2. Dynamic polymorphism is the polymorphic resolution identified at runtime and is achieved through method overriding. | ||||
Sample Code for overloading Sample Code for overriding | ||||
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Like Discuss Correct / Improve  polymorphism  object oriented programming (oops)  oops concepts  oops concepts Asked in 108 Companies Basic   frequent | ||||
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Advanced level question usually asked in High end product companies. Have been asked in Google and Amazon (Based on 1 Feedback) | ||||
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Ans. The Java runtime environment deletes objects when it determines that they are no longer being used. This process is known as garbage collection. The Java runtime environment supports a garbage collector that periodically frees the memory used by objects that are no longer needed. The Java garbage collector is a mark-sweep garbage collector that scans Java dynamic memory areas for objects, marking those that are referenced. After all possible paths to objects are investigated, those objects that are not marked (i.e. are not referenced) are known to be garbage and are collected. | ||||
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Like Discuss Correct / Improve  java   garbage collection   java memory management   advanced Asked in 21 Companies intermediate   frequent | ||||
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Frequently asked question in companies using hibernate. | ||||
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Ans. 1. First level cache is enabled by default whereas Second level cache needs to be enabled explicitly. 2. First level Cache came with Hibernate 1.0 whereas Second level cache came with Hibernate 3.0. 3. First level Cache is Session specific whereas Second level cache is shared by sessions that is why First level cache is considered local and second level cache is considered global. | ||||
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Like Discuss Correct / Improve  hibernate   orm   hibernate cache   architecture   technical lead   first level cache vs second level cache Asked in 18 Companies Intermediate   frequent | ||||
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Ans. EFS is file storage whereas S3 is object storage. EFS is filesystem presented over IP network as normal OS drive, while S3 is HTTP accessed store. EFS is capable of being mounted whereas S3 doesn't. S3 has capabilities beyond just filesystem, there is whole metadata part where you can store info about your objects in S3. As S3 is accessed over http , it's capable of hosting a static web site on it's own whereas EFS needs a computing and frontend service to have such capability. | ||||
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Like Discuss Correct / Improve  aws s3  aws storage  amazon cloud storage  amazon s3  aws ehs  aws s3  aws storage  amazon cloud storage  amazon s3 vs aws efs | ||||
Frequently asked question for intermediate developers. Frequently asked in HCL Technologies and EPAM. | ||||
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Ans. Volatile is a declaration that a variable can be accessed by multiple threads and hence shouldnt be cached. | ||||
Sample Code for volatile | ||||
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Like Discuss Correct / Improve  java   oops   synchronization   volatile   java keywords Asked in 42 Companies intermediate   frequent | ||||
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Ans. A DOM (Document Object Model) parser creates a tree structure in memory from an input document whereas A SAX (Simple API for XML) parser does not create any internal structure. A SAX parser serves the client application always only with pieces of the document at any given time whereas A DOM parser always serves the client application with the entire document no matter how much is actually needed by the client. A SAX parser, however, is much more space efficient in case of a big input document whereas DOM parser is rich in functionality. Use a DOM Parser if you need to refer to different document areas before giving back the information. Use SAX is you just need unrelated nuclear information from different areas. Xerces, Crimson are SAX Parsers whereas XercesDOM, SunDOM, OracleDOM are DOM parsers. | ||||
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Like Discuss Correct / Improve  java   xml   parsers   sax   dom parser   difference   architecture   technical lead   technical architect  markup language   sax vs dom Asked in 14 Companies   frequent | ||||
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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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Like Discuss Correct / Improve  aws cloud formation  aws ami  amazon ami  aws ami  amazon ami vs aws cloud formation | ||||
Frequently asked in high end product companies. Frequently asked in Deloitte. | ||||
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Ans. https://medium.com/javarevisited/internal-working-of-hashmap-in-java-97aeac3c7beb#:~:text=HashMap%20internally%20uses%20HashTable%20implementation,the%20entries%20into%20the%20map. | ||||
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Like Discuss Correct / Improve  hashmap  collections  hashmap internal implementation Asked in 20 Companies expert   frequent | ||||
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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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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 | ||||
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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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Like Discuss Correct / Improve  aws s3  aws storage  amazon cloud storage  amazon s3 | ||||
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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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Like Discuss Correct / Improve  aws s3  aws storage  amazon cloud storage  amazon s3 | ||||
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Ans. EC2 - Time and Reservation , Instance Type ( Memory , Computation power ) S3 - Accessibility Frequency , Data Transfer , Storage Space CloudFront - Geography, No of Locations EBS - IOPS, Access Frequency | ||||
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Like Discuss Correct / Improve  aws ec2  aws computing  amazon cloud computing  amazon ec2  aws s3  aws storage  amazon cloud storage  amazon s3  aws cloudfront  amazon cloudfront  aws ebs | ||||
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Ans. Simple Weighted Latency Failover GeoLocation Multivalue | ||||
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Like Discuss Correct / Improve  aws route53 Asked in 1 Companies | ||||
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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) | ||||
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Ans. The Spring Application starts with the main() method. Spring Application has a Main Class where main() method has a static method run() which takes two arguments, one is class type and second is string array. Spring Application will bootstrap our application, starts auto-configured tomcat web server.When SpringApplication.run() command is invoked, the Application Context is created. The createApplicationContext method checks if it is a web or standalone application based on the type it creates for the context.When the constructor of the context is invoked, it will register the annotated class beans with the context. All your @Repository, @Component, @Service, and Controller beans will be registered and the context is returned. | ||||
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Ans. Single instance means there is only 1 instance that will bear all the traffic load whereas Load balanced server means that there will be a cluster of servers that will host the application and load will be balanced distributed among them. Auto Scaling means that the number of instances will be expanded / shrunken based on the rule. Rule could be the traffic count , response time etc. | ||||
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Like Discuss Correct / Improve  load balancing  auto scaling  aws  elastic beanstalk | ||||
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Ans. Cloud Computing is a way of using IT infrastructure with following traits - 1. On Demand Infrastructure 2. Broad Network Access 3. Resource Pooling 4. Rapid Elasticity 5. Measured Service | ||||
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Like Discuss Correct / Improve  google cloud platform (GCP)  Amazon Web Services (AWS | ||||
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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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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 | ||||
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Ans. Cloud Formation does not have any additional cost but you are charged for the underlying resources it builds. | ||||
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Like Discuss Correct / Improve  aws cloud formation | ||||
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Ans. In AWS Lambda we can run a function in synchronous or asynchronous mode. In synchronous mode, if AWS Lambda function fails, then it will just give an exception to the calling application. In asynchronous mode, if AWS Lambda function fails then it will retry the same function at least 3 times.If AWS Lambda is running in response to an event in Amazon DynamoDB or Amazon Kinesis, then the event will be retried till the Lambda function succeeds or the data expires. In DynamoDB or Kinesis, AWS maintains data for at least 24 hours. | ||||
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Like Discuss Correct / Improve  aws lambda  aws serverless computing  amazon cloud serverless computing  amazon lambda | ||||
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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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Like Discuss Correct / Improve  aws ami  amazon ami | ||||
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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)   Google Cloud Platform (GCP) | ||||
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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 | ||||
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Ans. It saves Network traffic and facilitates faster delivery by hosting bulk media and cached data near to client. | ||||
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Like Discuss Correct / Improve  aws edge locations | ||||