AWS INTERVIEW QUESTIONS

Updated: Jul 13, 2020




Q: List the components required to build Amazon VPC?

  • Ans: Subnet, Internet Gateway, NAT Gateway, HW VPN Connection, Virtual Private Gateway, Customer Gateway, Router, Peering Connection, VPC Endpoint for S3, Egress-only Internet Gateway.


Q: How do you safeguard your EC2 instances running in a VPC?

  • Ans: Security Groups can be used to protect your EC2 instances in a VPC. We can configure both INBOUND and OUTBOUND traffic in a Security Group which enables secured access to your EC2 instances. Security Group automatically denies any unauthorized access to your EC2 instances.


Q: In a VPC how many EC2 instances can you use?

  • Ans: Initially you are limited to launch 20 EC2 Instances at one time. Maximum VPC  size is 65,536 instances.


Q: Can you establish a peering connection to a VPC in a different REGION?

  • Ans: Not possible. Peering Connection are available only between VPC in the same region.


Q: Can you connect your VPC with a VPC owned by another AWS account?

  • Ans: Yes, Possible. Provided the owner of other VPCs accepts your connection.


Q: What are all the different connectivity options available for your VPC?

  • Ans: Internet Gateway, Virtual Private Gateway, NAT, EndPoints, Peering Connections.


Q: Can a EC2 instance inside your VPC connect with the EC2 instance belonging to other VPCs?

  • Ans: Yes, Possible. Provided an Internet Gateway is configured in such a way that traffic bounded for EC2 instances running in other VPCs.


Q: How can you monitor network traffic in your VPC?

  • Ans: It is possible using Amazon VPC Flow-Logs feature.


Q: Difference between Security Groups and ACLs in a VPC?

  • Ans: A Security Group defines which traffic is allowed TO or FROM  EC2 instance. Whereas ACL, controls at the SUBNET level, scrutinize the traffic TO or FROM a Subnet.


Q: Hon an EC2 instance in a VPC establish the connection with the internet?

  • Ans: Using either a Public IP or an Elastic IP.


Q: Different types of Cloud Computing as per services?

  • Ans:  PAAS (Platform As A Service), IAAS (Infrastructure As A Service), SAAS (Software As A Service)


Q: What is Auto Scaling?

  • Ans: Creating duplicate instances during heavy business hours. Scale-IN and Scale-OUT are two different statues of Scaling. Scale-IN: Reducing the instances. Scale-OUT: Increasing the instances by duplicating.


Q: What is AMI?

  • Ans: AMI is defined as Amazon Machine Image. Basically it’s a template comprising software configuration part. For example, Operating System, DB Server, Application Server, etc.,


Q: Difference between Stopping and Terminating the Instances?

  • Ans: When you STOP an instance it is a normal shutdown. The corresponding EBS volume attached to that instance remains attached and you can restart the instance later. When you TERMINATE an instance it gets deleted and you cannot restart that instance again later. And any EBS volume attached with that instance also deleted.


Q: When you launch a standby Relational Database Service instance will it be available in the same Available Zone?

  • Ans: Not advisable. Because the purpose of having standby RDS  instance is to avoid an infrastructure failure. So you have to keep your standby RDS service in a different Availability Zone, which may have different infrastructure.


Q: Difference between Amazon RDS, DynamoDB and Redshift?

  • Ans: RDS is meant for structured data only. DynamoDB is meant for unstructured data which is a NoSQL service. Redshift is a data warehouse product used for data analysis.


Q: What are Lifecycle Hooks?

  • Ans: Lifecycle Hooks are used in Auto Scaling. Lifecycle hooks enable you to perform custom actions by pausing instances as an Auto Scaling group launches or terminates them. Each Auto Scaling group can have multiple lifecycle hooks.


Q: What is S3?

  • Ans: S3 stands for Simple Storage Service, with a  simple web service interface to store and retrieve any amount of data from anywhere on the web.


Q: What is AWS Lambada?

  • Ans: Lambda is an event-driven platform. It is a compute service that runs code in response to events and automatically manages the compute resources required by that code.


Q: In S3 how many buckets can be created?

  • Ans: By default 100 buckets can be created in a region.


Q: What is CloudFront?

  • Ans: Amazon CloudFront is a service that speeds up transfer of your static and dynamic web content such as HTML files, IMAGE files., etc., CloudFront delivers your particulars thru worldwide data centers named Edge Locations.


Q: Brief about S3 service in AWS?

  • Ans: S3, a Simple Storage Service from Amazon. You can move your files TO and FROM S3. Its like a FTP storage. You can keep your SNAPSHOTS in S3. You can also ENCRYPT your sensitive data in S3.


Q: Explain Regions and Available Zones in EC2?

  • Ans: Amazon has hosted EC2 in various locations around the world. These locations are called REGIONS. For example in Asia, Mumbai is one region and Singapore is another region. Each region is composed of isolated locations which are known as AVAILABLE ZONES.    Region is independent. But the Available Zones are linked thru low-latency links.


Q: What are the two types  of Load Balancer?

  • Ans: Classic LB and Application LB. ALB is the Content Based Routing.


Q: Can a AMI be shared?

  • Ans: Yes. A developer can create an AMI and share it with other developers for their use. A shared AMI is packed with the components you need and you  can customize the same as per your needs. As you are not an owner of a shared AMI there is a risk always involved.


Q: What is a Hypervisor?

  • Ans: A Hypervisor is a kind of software that enables Virtualization. It combines physical hardware resources into a platform which is delivered virtually to one or more users. XEN is the Hypervisor for EC2.


Q: Key Pair and its uses?

  • Ans: You use Key Pair to login to your Instance in a secured way. You can create a key pair using EC2 console. When your instances are spread across regions you need to create key pair in each region.


Q: What is the feature of ClassicLink?

  • Ans: ClassicLink allows instances in EC2 classic platform to communicate with instances in VPC using Private IP address. EC2 classic platform instances cannot not be linked to more than one VPC at a time.


Q: Can you edit a Route Table in VPC?

  • Ans: Yes. You can always modify route rules to specify which subnets are routed to the Internet gateway, the virtual private gateway, or other instances.


Q: How many Elastic IPs can you create?

  • Ans: 5 VPC Elastic IP addresses per AWS account per region


Q: Can you ping the router or default gateway that connects your subnets?

  • Ans: NO, you cannot. It is not supported. However you can ping EC2 instances within a VPC, provided your firewall, Security Groups and network ACLs allows such traffic.


Q: How will you monitor the network traffic in a VPC?

  • Ans: Using Amazon VPC Flow Logs feature.


Q: Can you make a VPC available in multiple Available Zones?

  • Ans: Yes.


Q: How do you ensure an EC2 instance is launched in a particular Available Zone?

  • Ans: After selecting your AMI Template and Instance Type, in the third step while configuring the instance you must select the SUBNET in which you wish to launch your instance. It will be launched in the AZ associated with that SUBNET.


Q: For Internet Gateways do you find any Bandwidth constraints?

  • Ans: NO. Normally an IG is HORIZONTALLY SCALLED, Redundant and Highly Available. It is not having nay Bandwidth constraints usually.


Q: What is the significance of a Default VPC?

  • Ans: When you launch your instances in a Default VPC in a Region, you would be getting the benefit of advanced Network Functionalities. You can also make use of Security Groups, multiple IP addresses, and multiple Network interfaces.


Q: Can you make use of default EBS Snapshots?

  • Ans: You can use, provided if it is located in the same region where your VPC is presented.


Q: What will happen when you delete a PEERING CONNECTION in your side?

  • Ans: The PEERING CONNECTION available in the other side would also get terminated. There will no more traffic flow.


Q: Can you establish a Peering connection to a VPC in a different region?

  • Ans: NO. Its possible between VPCs in the same region.


Q: Can you connect your VPC with a VPC created by another AWS account?

  • Ans: Yes. Only when that owner accepts your peering connection request.


Q: When you delete your DB instance what will happen to your backups and DB snapshots?

  • Ans: When a DB instance is deleted, RDS retains the user-created DB snapshot along with all other manually created DB snapshots. Also automated backups are deleted and only manually created DB Snapshots are retained.


Q: What is the significance of an Elastic IP?

  • Ans: The Public IP is associated with the instance until it is stopped or terminated Only. A Public IP is not static. Every time your instance is stopped or terminated the associated Public IP gets vanished and a new Public IP gets assigned with that instance. To over come this issue a public IP can be replaced by an Elastic IP address, which stays with the instance as long as the user doesn’t manually detach it. Similarly when if you are hosting multiple websites on your EC2 server, in that case you may require more than one Elastic IP address.


Q: How will you use S3 with your EC2 instances?

  • Ans: Websites hosted on your EC2 instances can load their static contents directly from S3. It provides highly scalable, reliable, fast, inexpensive data storage infrastructure.


Q: Is this possible to connect your company datacenter to Amazon Cloud?

  • Ans: Yes, you can very well do this  by establishing a VPN connection between your company’s network and Amazon VPC.


Q: Can you change the Private IP of an EC2 instance while it is running or stopped?

  • Ans: A Private IP is STATIC. And it is attached with an instance throughout is lifetime and cannot be changed.


Q: What is the use of Subnets?

  • Ans: When a network has more number of HOSTS, managing these hosts can be tedious under a single large network. Therefore we divide this large network into easily manageable sub-networks (subnets) so that managing hosts under each subnet becomes easier.


Q: What is the use of Route Table?

  • Ans: Route Table is used to route the network pockets. Generally one route table would be available in each subnet. Route table can have any no. of records or information, hence attaching multiple subnets to a route table is also possible.


Q: Can you use the Standby DB instance for read and write along with your Primary DB instance?

  • Ans: Standby server cannot be used in parallel with primary server unless your Primary instance goes down.


Q: What is the use of Connection Draining?

  • Ans: Connection Draining is a service under Elastic Load Balancing. It keeps monitoring the healthiness of the instances. If any instance fails Connection Draining pulls all the traffic from that particular failed instance and re-route the traffic to other healthy instances.


Q: What is the role of AWS CloudTrail?

  • Ans: CloudTrail is designed for logging and tracking API calls. Also used to audit all S3 bucket accesses.


Q: What is the use of Amazon Transfer Acceleration Service?

  • Ans: ATA service speeds up your data transfer with the use of optimized network paths. Also, speed up your CDN up to 300% compared to normal data transfer speed


Q: What’s the difference between instance store and EBS?

Scenario

I’m not sure whether to store the data associated with my Amazon EC2 instance in instance store or  in an attached Amazon Elastic Block Store (Amazon EBS) volume. Which option is best for me?

  • Ans: Resolution

Some Amazon EC2 instance types come with a form of directly attached, block-device storage known as the instance store. The instance store is ideal for temporary storage, because the data stored in instance store volumes is not persistent through instance stops, terminations, or hardware failures. You can find more detailed information about the instance store at Amazon EC2 Instance Store.

For data you want to retain longer-term, or if you need to encrypt the data, we recommend using EBS volumes instead. EBS volumes preserve their data through instance stops and terminations, can be easily backed up with EBS snapshots, can be removed from instances and reattached to another, and support full-volume encryption. For more detailed information about EBS volumes, see Features of Amazon EBS.


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