30+ Most Asked AWS Interview Questions & Answers

The realm of cloud computing presents a plethora of opportunities, and mastering Amazon Web Services (AWS) can propel you towards a thriving career as an AWS architect. To ace that crucial job interview, Instaily Academy’s meticulously crafted compilation of AWS interview questions and answers is your key to success.

Whether you’re a seasoned AWS professional or just starting your journey, this comprehensive guide provides a deep dive into the most frequently asked AWS interview questions, accompanied by insightful and detailed explanations. Our team of AWS experts has carefully crafted these questions and answers, drawing upon their extensive experience in the industry and their understanding of MNC companies’ expectations.

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Q1. Can an EC2 instance inside your VPC connect with the EC2 instance belonging to other VPCs?

Ans: No, by default, instances in different Virtual Private Clouds (VPCs) cannot communicate with each other directly. VPCs in AWS are isolated from each other, and the communication between instances is limited to the boundaries of the VPC. If you need to enable communication between EC2 instances in different VPCs, you would typically use one of the following methods:

• VPC Peering: This allows you to connect two VPCs, enabling instances in those VPCs to communicate with each other as if they are on the same network.
• VPN Connection: You can establish a Virtual Private Network (VPN) connection between the VPCs to facilitate communication.
• AWS Direct Connect: For even more dedicated and higher bandwidth connections, you can use AWS Direct Connect to establish a direct physical connection between your on-premises data center and your VPC.

Q2. What are the components required to build Amazon VPC?

Ans: Building an Amazon Virtual Private Cloud (VPC) involves several key components. Here are the essential components required to create an Amazon VPC:

• CIDR Block: Define the IP address range for your VPC using Classless Inter-Domain Routing (CIDR) notation. This block determines the range of IP addresses that can be used within your VPC.
• Subnets: Divide the CIDR block into smaller subnets for better network organization. Each subnet is associated with an Availability Zone (AZ) and can be public or private. Public subnets typically have resources with public IP addresses, while private subnets do not have direct internet access.
• Route Tables: Create route tables to control the traffic between subnets within the VPC and to external networks. Each subnet is associated with a route table, and the route table specifies how traffic is directed.
• Internet Gateway: To enable internet access for resources in public subnets, attach an internet gateway to the VPC. This allows instances in public subnets to communicate directly with the internet.
• NAT Gateway or NAT Instance: For instances in private subnets to access the internet (for example, for software updates), you need either a Network Address Translation (NAT) gateway or a NAT instance. These components enable outbound traffic from private subnets.
• Elastic IP Addresses (EIP): If you’re using a NAT instance, associate an Elastic IP address with it to provide a persistent public IP address. NAT gateways come with their own static IP addresses and do not require Elastic IPs.
• Security Groups: Define security groups to control inbound and outbound traffic to instances. Security groups act as virtual firewalls at the instance level.
• Network Access Control Lists (NACLs): NACLs operate at the subnet level and provide an additional layer of security by controlling traffic entering and leaving the subnet.
• VPC Peering: Establish VPC peering connections to allow communication between instances in different VPCs.
• Virtual Private Network (VPN) or AWS Direct Connect: If you need to connect your VPC to your on-premises network, you can use either a VPN connection or AWS Direct Connect.

Q3. Can you establish a peering connection to a VPC in a different REGION?

Ans: Yes, you can establish a peering connection to a VPC in a different region. This is called an inter-region VPC peering connection. To do this, you will need to create a VPC peering connection request from the VPC in the source region to the VPC in the destination region. Once the request is accepted, the two VPCs will be connected and resources in the VPCs can communicate with each other as if they were in the same network.

Q4. Can you connect your VPC with a VPC owned by another AWS account?

Ans: Yes, you can connect your VPC with a VPC owned by another AWS account, as long as the VPCs are in the same AWS Region and have a mutual trust relationship. You can do this by creating a VPC peering connection, which is a networking connection between two VPCs that enables you to route traffic between them privately. Resources in peered VPCs can communicate with each other as if they are within the same network.

Q5. How do you safeguard your EC2 instances running in a VPC?

Ans: There are many ways to safeguard your Amazon EC2 instances running in a VPC. Here are some of the most important:

Use security groups to control inbound and outbound traffic

Security groups are a fundamental part of VPC security. They act as virtual firewalls that control the inbound and outbound traffic of your EC2 instances. You can use security groups to specify which protocols and ports are allowed to communicate with your instances. For example, you can create a security group that allows SSH traffic from your IP address and denies all other inbound traffic.

Use network ACLs to control traffic at the subnet level

Network ACLs (NACLs) are another way to control traffic in your VPC. They are similar to security groups, but they are applied at the subnet level instead of the instance level. This means that they apply to all instances in a subnet, regardless of their security group settings. NACLs can be used to control traffic between subnets, as well as between subnets and the internet.

Use IAM roles to restrict access to EC2 instances

IAM roles are a way to grant permissions to EC2 instances without having to manage access keys. This is a more secure way to manage access to your instances, as it eliminates the need to store and manage access keys. You can use IAM roles to grant permissions to specific users or groups of users.

Use Amazon CloudTrail to audit activity in your VPC

Amazon CloudTrail is a service that logs all API calls made to your AWS account. This includes API calls made to manage your VPC, such as creating and deleting instances, and creating and deleting security groups. You can use CloudTrail to audit activity in your VPC and identify any unauthorized changes.

Keep your software up to date

One of the most important things you can do to safeguard your EC2 instances is to keep your software up to date. This includes your operating system, your applications, and your security software. Outdated software can contain vulnerabilities that can be exploited by attackers.

Use strong passwords and two-factor authentication

When creating EC2 instances, it is important to use strong passwords and two-factor authentication. This will help to prevent unauthorized access to your instances.

Monitor your VPC for suspicious activity

It is important to monitor your VPC for suspicious activity. This includes looking for unusual traffic patterns, unauthorized access attempts, and changes to your security groups and NACLs.

Use a managed security service

If you do not have the time or resources to manage your VPC security yourself, you can consider using a managed security service. These services provide comprehensive security for your VPC, including threat detection, intrusion prevention, and vulnerability management.

By following these tips, you can help to safeguard your EC2 instances running in a VPC and protect your data from unauthorized access.

Q6. In a VPC how many EC2 instances can you use?

Ans: The number of Amazon Elastic Compute Cloud (EC2) instances we can use in a VPC is limited by the instance quota for our AWS account. We can request an increase to our instance quota by contacting AWS Support.

There are two types of instance quotas: regional instance quotas and Availability Zone instance quotas. Regional instance quotas apply to the entire AWS Region, while Availability Zone instance quotas apply to a specific Availability Zone. We can view our instance quotas in the Amazon EC2 console.

The default regional instance quota for new AWS accounts is 20 On-Demand Instances, 20 Spot Instances, and 20 Reserved Instances. The default Availability Zone instance quota for new AWS accounts is 10 On-Demand Instances, 10 Spot Instances, and 10 Reserved Instances.

We can request an increase to our instance quota by contacting AWS Support.

Q7. Can you ping the router or default gateway that connects your subnets?

Ans: Yes, we can ping the router or default gateway that connects your subnets, as long as we know its IP address and it is configured to respond to ping requests. Pinging the router or default gateway can help us test the network connectivity and performance between our subnets and the internet or other networks.

Q8. How many Elastic IPs can you create?

Ans: We can create up to 5 Elastic IP addresses per Region by default. However, we can request an increase for this limit from AWS if we need more Elastic IP addresses for our account. We can also release any unused Elastic IP addresses that we no longer need to free up our quota.

Q9. What will happen when you delete a PEERING CONNECTION on your side?

Ans: When we delete a peering connection on our side, the following things will happen:

• The peering connection status will change to Deleting and then Deleted on your side.
• The peering connection status will change to Failed on the other side.
• The traffic between the peered VPCs will be interrupted and no longer routed through the peering connection.
• The route tables and security groups for the peered VPCs will no longer apply to the peering connection.
• The peering connection will no longer be visible or editable on your side, but it will remain visible on the other side for a period of time.
• The peering connection will be automatically deleted on the other side after a period of time, or the other owner can manually delete it.

Q10. Can you make use of default EBS Snapshots?

Ans: Yes, we can make use of default EBS snapshots, which are snapshots that are automatically created by AWS for your EBS volumes. Default EBS snapshots are created when we enable the following features for our EBS volumes:

• Fast snapshot restore: This feature enables us to create EBS volumes from snapshots that are fully initialized and ready to use. AWS creates a default snapshot of our volume every 12 hours and stores it in the designated Availability Zone. We can use these snapshots to create new volumes with fast snapshot restore enabled, which eliminates the need to wait for the data to be loaded from Amazon S3.

• Data Lifecycle Manager: This feature enables us to automate the creation, retention, and deletion of snapshots for our EBS volumes. We can create a lifecycle policy that specifies the schedule, frequency, and retention period for our snapshots. AWS creates a default snapshot of our volume according to our policy and tags it with the prefix DLM-Managed-Snapshot.

• AWS Backup: This feature enables us to centrally manage and automate the backup and restore of our AWS resources, including EBS volumes. We can create a backup plan that defines the backup frequency, retention period, and backup window for our resources. AWS creates a default snapshot of our volume according to our backup plan and tags it with the prefix AWSBackup.

Q11. Can you connect your company datacenter to Amazon Cloud?

Ans: Yes, it is possible to connect our company’s datacenter to Amazon Cloud. AWS provides multiple options for establishing a connection between an on-premises datacenter and the Amazon Cloud. Two common methods for achieving this connectivity are through Virtual Private Network (VPN) connections and AWS Direct Connect.

• Virtual Private Network (VPN): With a VPN connection, we can securely extend our on-premises network into an Amazon VPC (Virtual Private Cloud) over the internet. This allows for secure communication between our datacenter and AWS resources.

• AWS Direct Connect: For a more dedicated and higher-bandwidth connection, we can use AWS Direct Connect to establish a direct physical connection between our on-premises datacenter and one of the AWS Direct Connect locations. This provides a private network connection, reducing latency and providing a more consistent network experience.

Q12. What is the role of AWS CloudTrail?

Ans: The role of AWS CloudTrail is to provide a detailed record of all actions taken within an AWS account. CloudTrail is a service that helps you enable operational and risk auditing, governance, and compliance of your AWS account. CloudTrail records all API activity within an AWS account, including actions taken by users, roles, or AWS services. You can use CloudTrail to monitor and analyze your AWS account activity, troubleshoot issues, detect anomalies, and improve security.

Q13. What are the two types of Load Balancer?

Ans: There are different ways to classify load balancers, but one common method is to divide them into two types based on their function: Layer 4 load balancers and Layer 7 load balancers.

Layer 4 load balancers operate at the transport layer of the OSI model, which means they distribute traffic based on the source and destination IP addresses and ports of the packets.

Layer 7 load balancers operate at the application layer of the OSI model, which means they distribute traffic based on the content and characteristics of the packets.

Q14. What is a Key Pair and its uses?

Ans: In AWS, a key pair consists of a public key and a private key, and it is used to securely connect to Amazon EC2 instances. Here’s a breakdown of its components and uses:

• Public Key: The public key is used to encrypt data, and it can be shared openly. In the context of AWS, when you launch an EC2 instance, you specify the key pair to use, and the corresponding public key is placed on the instance.
• Private Key: The private key is kept secure and is used to decrypt data that was encrypted with the corresponding public key. Only the person with the private key can decrypt this data. When you connect to an EC2 instance, you use the private key to authenticate yourself.

Uses of Key Pairs in AWS:

• SSH Authentication: Key pairs are primarily used for SSH (Secure Shell) authentication when connecting to EC2 instances.
• Secure Communication: Key pairs ensure secure communication between your local machine and the EC2 instance.
• Instance Access Control: By associating a key pair with an EC2 instance, you control who has access to that instance.
• Key Pair Management: AWS allows you to create, import, and manage key pairs through the AWS Management Console, AWS Command Line Interface (CLI), or SDKs. 
• Key Pair Rotation: For security best practices, it’s advisable to rotate key pairs periodically. 

Q15. How will you use S3 with your EC2 instances?

Ans: To utilize Amazon S3 with my EC2 instances, I would employ S3 as a scalable and durable object storage service, seamlessly integrating it with EC2 for various use cases. Here are several ways I would leverage S3 with my EC2 instances:

• Data Storage: I would use S3 to store and retrieve data that doesn’t need to reside directly on the EC2 instance.
• Static Website Hosting: S3 can be utilized to host static websites, and I would configure my S3 bucket for website hosting. 
• Data Transfer: If my EC2 instances generate data that needs to be shared across multiple instances or regions, I would store this data in an S3 bucket.
• Backup and Restore: S3 provides a reliable solution for backing up critical data from EC2 instances.
• Integration with AWS Services: I would explore integrations with other AWS services, such as Amazon EMR for big data processing or AWS Lambda for serverless computing, where S3 can act as a data source or target.
• Versioning and Lifecycle Policies: Taking advantage of S3 versioning, I would implement version control for objects stored in S3 buckets. 
• Security and Access Control: I would implement proper access controls using AWS Identity and Access Management (IAM) to ensure that EC2 instances have the necessary permissions to interact with specific S3 buckets.

Q16. Can you use the Standby DB instance for read and write along with your Primary DB instance?

Ans: Yes, you can use the Standby DB instance for read and write along with your Primary DB instance. In fact, this is the primary purpose of a Standby DB instance. A Standby DB instance is a replica of your Primary DB instance that is kept up-to-date with the latest changes. This means that you can use the Standby DB instance to offload read traffic from your Primary DB instance, which can improve performance and scalability. You can also use the Standby DB instance to perform write operations, but this should only be done in emergencies or when the Primary DB instance is unavailable.

Q17. How will you monitor the network traffic in a VPC?

Ans: To monitor the network traffic in a VPC, you can use Amazon VPC flow logs and Amazon VPC traffic mirroring.

Amazon VPC flow logs allow you to capture detailed information about the traffic going to and from network interfaces in your VPCs. You can use VPC Flow Logs to diagnose overly-restrictive security group rules, monitor the traffic that is reaching your instance, and analyze network traffic patterns.

Amazon VPC traffic mirroring is a feature that allows you to copy network traffic from a network interface of an Amazon EC2 instance and send it to out-of-band security and monitoring appliances for deep packet inspection. You can use this feature to detect network and security anomalies, gain operational insights, implement compliance and security controls, and troubleshoot issues.

Q18. What is the feature of ClassicLink?

Ans: From the interviewee’s point of view, ClassicLink is a feature that allows EC2-Classic instances to communicate with resources deployed in VPCs. This feature enables you to connect your EC2-Classic instances to a VPC and use VPC security groups to control inbound and outbound traffic.

When you enable ClassicLink for a VPC, you can associate one or more of your EC2-Classic instances with the VPC. Once you have associated an instance with a VPC, you can use VPC security groups to control inbound and outbound traffic to the instance.

Q19. Can you edit a Route Table in VPC?

Ans: Yes, you can edit a route table in VPC. To do this, you can use either the AWS Management Console or the AWS CLI.

Using the AWS Management Console:

1. Open the Amazon VPC console at https://console.aws.amazon.com/vpc/.
2. In the navigation pane, choose Route Tables.
3. Select the route table that you want to edit.
4. Choose Actions, and then choose Edit routes.
5. To add a route, choose Add route.
6. For Destination, enter the destination CIDR block, a single IP address, or the ID of a prefix list.
7. For Target, choose a target.
8. To delete a route, select the route, and then choose Remove.
9. To modify a route, select the route, and then change the Destination or Target.
10. Choose Save changes.

Using the AWS CLI:

aws ec2 describe-route-tables

aws ec2 create-route

aws ec2 delete-route

aws ec2 replace-route

Q20. What is the difference between Stopping and Terminating the Instances?

Ans: When you stop an instance, the instance will be shutdown and the virtual machine that was provisioned for you will be permanently taken away and you will no longer be charged for instance usage. The key difference between stopping and terminating an instance is that the attached bootable EBS volume will not be deleted. The data on your EBS volume will remain after stopping while all information on the local (ephemeral) hard drive will be lost as usual. The volume will continue to persist in its availability zone. Standard charges for EBS volumes will apply.

Therefore, you should only stop an instance if you plan to start it again within a reasonable timeframe. Otherwise, you might want to terminate an instance instead of stopping it for cost saving purposes.

Q21. What is the difference between vertical and horizontal scaling in AWS? 

Ans: Vertical scaling refers to increasing the size of an instance, while horizontal scaling refers to increasing the number of instances. Vertical scaling is more suitable for applications that require more resources, while horizontal scaling is more suitable for applications that require high availability and fault tolerance.

Q22. When you launch a standby Relational Database Service instance will it be available in the same Available Zone?

Ans: It is not advisable to launch a standby Relational Database Service instance in the same Availability Zone as the primary instance. The purpose of having a standby RDS instance is to avoid infrastructure failure, so it is recommended to keep the standby RDS service in a different Availability Zone, which may have different infrastructure.

Q23. What is the significance of an Elastic IP?

Ans: An Elastic IP address is a static IPv4 address that is allocated to your AWS account and is reachable from the internet. It is designed for dynamic cloud computing and can mask the failure of an instance or software by remapping to another instance in your account.

Q24. What is the difference between Security Groups and ACLs in a VPC?

Ans: Security groups operate at the instance level, while network ACLs operate at the subnet level. Security groups support only allow rules, while network ACLs support allow rules and deny rules. Security groups are stateful, while network ACLs are stateless.

Q25. What is AMI?

Ans: An Amazon Machine Image (AMI) is a pre-configured virtual machine image that is used to create an EC2 instance. It contains all the information required to launch an instance, including the operating system, application server, and applications. You can launch multiple instances from a single AMI when you require multiple instances with the same configuration.

Q26. Explain Regions and Available Zones in EC2?

Ans: An AWS Region is a physical location in the world where AWS has multiple data centers. Each Region consists of multiple Availability Zones, which are isolated locations within the Region that are engineered to be independent of each other. Each Availability Zone has its own power source, network, and connectivity to the internet. By launching instances in separate Availability Zones, you can protect your applications from the failure of a single location.

Q27. How will you monitor the network traffic in your VPC?

Ans: You can monitor network traffic in your VPC using the following tools:

1. VPC Flow Logs: This tool captures detailed information about the traffic going to and from network interfaces in your VPCs.
2. IPAM: This tool helps you plan, track, and monitor IP addresses for your workloads.
3. Amazon VPC traffic mirroring: This tool allows you to monitor network traffic by copying network traffic from an elastic network interface of an Amazon EC2 instance to a destination network interface.

Q28. Can you make a VPC available in multiple Available Zones?

Ans: Yes, you can make a VPC available in multiple Availability Zones. You can launch instances in separate Availability Zones to protect your applications from the failure of a single location.

Q29. How do you ensure an EC2 instance is launched in a particular Available Zone?

Ans: You can launch an EC2 instance in a particular Availability Zone by specifying the Availability Zone in which you want to launch the instance while creating the instance.

Q30. Can you connect your VPC with a VPC created by another AWS account?

Ans: Yes, you can connect your VPC with a VPC created by another AWS account using VPC peering. VPC peering enables you to route traffic via private IP addresses between two peered VPCs.

Q31. What is the difference between Amazon RDS, DynamoDB and Redshift?

Ans: Amazon RDS is a managed relational database service that supports six popular database engines, including Amazon Aurora, MySQL, MariaDB, PostgreSQL, Oracle, and Microsoft SQL Server. Amazon DynamoDB is a key-value and document database that is designed to deliver single-digit millisecond performance at any scale. Amazon Redshift is a fully managed, petabyte-scale data warehouse service that makes it simple and cost-effective to analyze all your data using your existing business intelligence tools.

Q32. Can an AMI be shared?

Ans: Yes, an AMI can be shared with specific AWS accounts without making the AMI public. You can share an AMI with specific AWS accounts by providing the AWS account IDs.

Q33. For Internet Gateways do you find any Bandwidth constraints?

Ans: No, an internet gateway is horizontally-scaled, redundant, and highly available. It does not cause availability risks or bandwidth constraints on your network traffic.

Q34. What is the significance of a Default VPC?

Ans: A default VPC is a virtual private cloud that is automatically created for your AWS account. It allows you to launch instances without specifying a subnet and provides access to the internet by default. A default VPC is suitable for getting started quickly and for launching public instances such as a blog or simple website.

Q35. What are the different types of Cloud Computing as per services?

Ans: There are different types of cloud computing services. One way to categorize them is by Infrastructure as a Service (IaaS), Platform as a Service (PaaS), Software as a Service (SaaS), Network as a Service (NaaS), and Function as a Service (FaaS). Another way to categorize them is by private clouds, public clouds, hybrid clouds, and multi-clouds.

Q36. What is Auto Scaling?

Ans: Auto Scaling is a service that automatically adjusts the number of Amazon EC2 instances in an Auto Scaling group according to the changes in demand for your application. You can use Auto Scaling to ensure that you have the correct number of Amazon EC2 instances available to handle the load for your application.