1.What are the different types of queues available in SQS?
SQS offers two types of queues:
Standard queues provide at-least-once delivery of messages and offer high throughput, while FIFO queues provide exactly once processing and preserve the order in which messages are sent.
2.What is the maximum message size supported by SQS?
The maximum message size supported by SQS is 256 KB for standard queues and 256 KB for FIFO queues. If a message exceeds this limit, it must be stored externally and a reference to it can be sent as a message in the queue.
3.What programming languages are supported by AWS Lambda?
AWS Lambda supports a wide range of programming languages, including Node.js, Python, Java, C#, Ruby, Go, and PowerShell. This allows developers to write Lambda functions in their preferred language.
4.How does Lambda handle scaling and concurrency?
Lambda automatically scales horizontally to handle incoming request traffic. It provisions new instances of your function as needed and automatically balances the load across these instances. Each instance of a Lambda function can handle multiple requests concurrently, and Lambda manages the concurrency on your behalf.
5.What is the maximum execution duration allowed for a Lambda function?
The maximum execution duration for a Lambda function is 900 seconds (15 minutes). If a function runs beyond this limit, it will be terminated by Lambda.
6.What are the different event sources that can trigger a Lambda function?
Lambda supports various event sources, including:
Object-created events in Amazon S3 buckets
DynamoDB stream events
Kinesis stream events
SNS (Simple Notification Service) messages
SQS (Simple Queue Service) messages
CloudWatch Events (scheduled events or custom events)
API Gateway requests
7.Can you configure VPC (Virtual Private Cloud) access for Lambda functions? If so, how?
Yes, Lambda functions can be configured to access resources within a VPC. You can specify the VPC and subnets in the function configuration, allowing the function to access resources such as RDS databases or resources hosted within the VPC.
8.What is the difference between provisioned concurrency and on-demand concurrency in Lambda?
Provisioned concurrency allows you to allocate a specific number of instances to be kept warm and ready to serve requests. This helps reduce latency caused by cold starts. On the other hand, on-demand concurrency allows Lambda to automatically manage the scaling of function instances based on the incoming request traffic.
9.How can you control the execution environment and dependencies of a Lambda function?
Lambda functions run in a specific execution environment provided by AWS. You can package your function code along with its dependencies, libraries, and custom runtimes in a deployment package or container image. By controlling the package, you can manage the execution environment and dependencies of your Lambda function.
10.What are the different storage classes available in Amazon S3?
Amazon S3 offers several storage classes, each designed for different use cases and cost considerations:
Standard: The default storage class with high durability and availability.
Intelligent Tiering: Automatically moves data between frequent and infrequent access tiers based on access patterns.
Standard-IA (Infrequent Access): Designed for data that is accessed less frequently but requires rapid access when needed.
One Zone-IA: Similar to Standard-IA but stores data in a single availability zone, reducing costs.
Glacier: Suitable for long-term archival storage with lower retrieval time but higher retrieval costs.
Glacier Deep Archive: Designed for long-term retention of data that is rarely accessed, with the lowest storage cost but longer retrieval time.
11.How can you control access to objects stored in Amazon S3?
Access to objects in Amazon S3 can be controlled using a combination of bucket policies, access control lists (ACLs), and IAM (Identity and Access Management) policies. Bucket policies and IAM policies are generally recommended for managing access control as they provide more granular control and flexibility.
12.What is S3 Transfer Acceleration, and how does it work?
S3 Transfer Acceleration is a feature that enables fast, easy, and secure file transfers to Amazon S3 over long distances. It utilizes the AWS Edge Network to optimize transfer speed by leveraging CloudFront's globally distributed network of edge locations. By enabling Transfer Acceleration for a bucket, data is routed through these edge locations, reducing the time it takes to upload or download objects.
13.Can you share objects publicly in Amazon S3?
Yes, you can make objects publicly accessible in Amazon S3 by configuring the appropriate permissions. This can be done through bucket policies or by setting the object ACL (Access Control List) to grant public read access.
14.How can you monitor Amazon S3 bucket activity?
Amazon S3 provides various monitoring and logging options to track bucket activity, such as:
S3 Server Access Logging: Logs all requests made to your bucket and stores the access logs in a separate bucket.
AWS CloudTrail: Captures API activity for your bucket, providing detailed information about the actions taken on your resources.
S3 Storage Lens: Provides a comprehensive view of your storage usage, activity trends, and recommendations for cost optimization.
15.How does an Elastic Load Balancer handle session persistence (sticky sessions)?
Elastic Load Balancers support session persistence through cookies. By enabling sticky sessions, the load balancer associates a cookie with a specific target (such as an EC2 instance) and ensures that subsequent requests from the same client are directed to the same target.
16.Can you explain the concept of cross-zone load balancing in Elastic Load Balancers?
Cross-zone load balancing is a feature in Elastic Load Balancers that ensures even distribution of traffic across all registered targets in all availability zones. By default, each target receives an equal share of traffic, regardless of the availability zone it belongs to.
17.How can you configure SSL/TLS encryption with an Elastic Load Balancer?
SSL/TLS encryption can be configured in Elastic Load Balancers through listeners. You can create an HTTPS listener and associate it with an SSL certificate stored in AWS Certificate Manager (ACM) or an Identity and Access Management (IAM) server certificate. This enables secure communication between clients and the load balancer.
18.How can you configure access logs for a Load Balancer?
Access logs for a Load Balancer can be configured using the Elastic Load Balancing service or the Amazon S3 service. When access logging is enabled, the Load Balancer records detailed information about each request and stores the logs in the specified Amazon S3 bucket.
19.How can you configure a Load Balancer to handle traffic spikes?
A Load Balancer can handle traffic spikes by scaling the number of healthy targets automatically based on the traffic demand. This can be achieved using features such as Auto Scaling, which dynamically adjusts the capacity of the target group based on predefined scaling policies, or by using AWS Lambda functions, which can be triggered by CloudWatch alarms to perform additional tasks.
20.Can you customize the security configuration of a Load Balancer?
Yes, a Load Balancer can be configured to use various security features, such as SSL/TLS certificates, security groups, and AWS WAF (Web Application Firewall). These features can help protect your applications against common attacks, such as cross-site scripting (XSS) and SQL injection.
21.Explain the concept of long polling in SQS.
Long polling is a feature in SQS that allows the consumers to retrieve messages from a queue with a longer polling duration. Instead of repeatedly polling the queue for new messages, the consumer sends a request to SQS and waits for a response. If messages are available within the specified wait time, SQS immediately returns them. Long polling reduces the number of empty responses and provides more efficient message retrieval.
22.How does Lambda integrate with other AWS services?
Lambda can be integrated with various AWS services through event sources. Some of the commonly used event sources include Amazon S3, Amazon DynamoDB, Amazon Kinesis, Amazon SNS, Amazon SQS, and AWS CloudWatch Events. These services can trigger the execution of a Lambda function based on specific events.
23.Explain the concept of cold starts in Lambda and how to mitigate them.
Cold starts occur when a Lambda function is invoked for the first time or after a period of inactivity, and AWS needs to provision a new instance to handle the request. This can result in increased latency. To mitigate cold starts, you can use techniques such as enabling provisioned concurrency, which keeps a specified number of instances warm and ready to handle requests.
24.What is the difference between standard queues and FIFO queues in SQS?
The main differences between standard queues and FIFO queues in SQS are:
Ordering: Standard queues provide best-effort ordering, while FIFO queues preserve the exact order in which messages are sent.
Deduplication: FIFO queues ensure exactly once processing using message deduplication, while standard queues might have occasional duplicate messages.
Throughput: Standard queues offer higher throughput and support a nearly unlimited number of transactions per second, while FIFO queues have a maximum limit of 300 transactions per second (TPS).
25.How does SQS handle message visibility and what is the significance of the visibility timeout?
When a consumer receives a message from a queue, SQS makes the message invisible to other consumers for a specific duration called the visibility timeout. During this time, the consumer processes the message. If the consumer successfully processes the message, it deletes it from the queue. If the processing fails, the message becomes visible again after the visibility timeout, allowing another consumer to process it. The visibility timeout provides a mechanism to handle message processing failures and avoid message duplication.
26.How does data consistency work in Amazon S3?
Amazon S3 provides read-after-write consistency for PUTS of new objects in your bucket and eventual consistency for overwrite PUTS and DELETES. This means that when you upload a new object, you can immediately read it, but when you update or delete an object, it may take some time for all the S3 servers to be aware of the change.
27.How can you optimize costs in Amazon S3?
There are several ways to optimize costs in Amazon S3:
a) Choose the appropriate storage class based on your data access patterns and requirements.
b) Implement lifecycle policies to automatically transition objects to lower-cost storage classes or delete them after a specific period.
c)Use S3 Intelligent-Tiering to automatically optimize storage costs by moving objects between frequent and infrequent access tiers.
d)Enable S3 Requester Pays for data transfer costs when the requester of the data bears the cost instead of the bucket owner.
28.What is auto-scaling in AWS and how does it work?
Auto Scaling is a feature in AWS that allows you to automatically scale your EC2 instances based on predefined conditions. It helps maintain application availability and dynamically adjusts the number of instances based on demand. Auto Scaling uses scaling policies to determine when to launch or terminate instances.
29.Explain the difference between public, private, and elastic IP addresses in AWS.
Public IP address: It is an IP address assigned to an instance that is reachable from the internet.
Private IP address: It is an IP address assigned to an instance within a VPC and is only reachable within the VPC or connected networks via private connectivity options.
Elastic IP address: It is a static, public IP address that users can allocate to their AWS account and assign to instances. Unlike a public IP, an Elastic IP address can be associated with an instance even if it is stopped and started, providing a consistent IP for the resource.
30.How can you secure data at rest in AWS?
AWS offers several options to secure data at rest:
1.Server-Side Encryption: AWS services like S3, EBS, and RDS provide encryption options to encrypt data at rest using keys managed by AWS.
2.Client-Side Encryption: Data can be encrypted on the client-side before storing it in AWS services.
3.AWS Key Management Service (KMS): It allows users to create and manage encryption keys to encrypt and decrypt data.
4.AWS CloudHSM (Cloud Hardware Security Module): Provides dedicated hardware security modules to securely generate and store encryption keys.
31.Explain the differences between Amazon RDS and Amazon DynamoDB.
Amazon RDS (Relational Database Service) is a managed relational database service that supports multiple database engines like MySQL, PostgreSQL, Oracle, and SQL Server. It simplifies the administration tasks such as backups, software patching, and scaling of the database instances.
Amazon DynamoDB is a fully managed NoSQL database service that provides fast and predictable performance at any scale. It is designed for applications that require single-digit millisecond latency and can handle high read and write throughput.
32.What is AWS CloudFormation and how is it useful?
AWS CloudFormation is a service that allows you to provision and manage AWS resources using code templates called CloudFormation templates. It helps automate the deployment and configuration of infrastructure resources in a predictable and repeatable manner. CloudFormation templates are written in JSON or YAML and define the desired state of your infrastructure, including EC2 instances, networking, security groups, and more.