20 AWS SQS Interview Questions and Answers

Amazon Simple Queue Service (SQS) is a popular cloud-based message queuing service. When applying for a position that involves working with SQS, it is important to be prepared to answer questions about the service. In this article, we discuss some of the most common SQS interview questions and how you should answer them.

AWS SQS Interview Questions and Answers

Here are 20 commonly asked AWS SQS interview questions and answers to prepare you for your interview:

1. What is AWS SQS?

Amazon Simple Queue Service (SQS) is a fully managed message queuing service that enables you to decouple and scale microservices, distributed systems, and serverless applications. SQS eliminates the complexity and overhead of managing and operating message-oriented middleware, and provides flexibility when you move to a microservices architecture. With SQS, you can send, store, and receive messages between software components at any volume, without losing messages or requiring other services to be always available.

2. How does Amazon SQS work?

Amazon SQS is a message queue service that allows you to decouple and scale microservices, distributed systems, and serverless applications. It does this by giving you a message queue that you can use to store messages while your application is processing them. This way, your application can continue to function even if one or more of its components are unavailable.

3. Can you explain the different types of queues available in SQS?

There are three different types of queues available in SQS: Standard, FIFO, and Dead Letter. Standard queues are the most basic type of queue and are best suited for simple workloads. FIFO queues are designed for more complex workloads where order is important, and Dead Letter queues are used for storing messages that cannot be processed successfully.

4. What’s the difference between standard and FIFO queue?

Standard queues are best-effort ordering, which means that messages might be delivered out of order. FIFO queues are guaranteed to preserve message ordering.

5. What are some advantages of using FIFO queue?

FIFO queue is a type of SQS queue that offers several benefits over other types of queues. FIFO queue is designed to ensure that messages are processed in the order that they are received. This can be helpful in ensuring that messages are processed in a timely manner. Additionally, FIFO queue can help to avoid message duplication.

6. In what scenarios should we use standard over FIFO Queue or vice versa?

FIFO queues are ideal for scenarios where message order must be preserved, such as when processing financial transactions. Standard queues are best for scenarios where message ordering is less important and message throughput is more critical, such as when sending email notifications.

7. What are the limitations of using SQS?

One of the key limitations of SQS is that it does not guarantee message delivery. This means that there is a possibility that messages may be lost, which could impact the accuracy of your data. Additionally, SQS is not a real-time messaging service, so there may be a delay in message delivery.

8. What do you understand about long polling with SQS?

Long polling is a way of checking for messages in an SQS queue without having to continuously poll the queue. With long polling, you can set up a “wait time” for the queue, and SQS will check the queue for messages during that time. If there are no messages in the queue, SQS will return an empty response. If there are messages in the queue, SQS will return up to 10 messages.

9. Can you explain how messages are stored in SQS?

Messages are stored in SQS in what is called a queue. A queue is a temporary repository for messages that are awaiting processing. When you create a queue, you need to specify how long you want the messages to be stored (in seconds). The maximum storage time for a message is 14 days.

10. What do you understand about dead letter queues in SQS?

A dead letter queue is a queue that is used to hold messages that cannot be processed successfully. This might happen if the message is malformed, or if the message fails to be processed after a certain number of attempts. Dead letter queues can be a useful tool for debugging purposes, as they can help you to identify why certain messages are not being processed correctly.

11. What happens if a message fails to be delivered to the recipient?

If a message fails to be delivered to the recipient, it will be placed back onto the queue and will be redelivered to the recipient.

12. Is there any limit on the number of queues you can have in your account?

No, there is no limit on the number of queues you can have in your account.

13. What would you recommend as the best strategy for sending and receiving messages from an SQS queue?

The best strategy for sending and receiving messages from an SQS queue would be to use the AWS SDK for your specific programming language. The AWS SDK will provide you with the necessary tools to interact with SQS queues, and it will also handle any authentication that is required.

14. Do you need to create a queue before adding messages to it?

No, you do not need to create a queue before adding messages to it.

15. How will you know that a message has been successfully added to a queue?

There are a few ways to know if a message has been successfully added to an AWS SQS queue. The first is to check the response code from the SQS service when the message is added. If the response code is 200, then the message was added successfully. The second way to check is to look at the SQS queue itself in the AWS console. If the message appears in the queue, then it was added successfully.

16. How can you delete a large volume of messages from an SQS queue?

One way to delete a large volume of messages from an SQS queue is to use the AWS CLI. With the AWS CLI, you can use the “aws sqs delete-message-batch” command to delete up to 10 messages at a time.

17. How can you ensure high availability when using SQS?

There are a few different ways to ensure high availability when using SQS. One way is to create multiple queues and spread the load across them. Another way is to use Amazon SQS Extended Client Library for Java which allows you to perform failover operations.

18. Can you give me an example of a real-world scenario where SQS can be used effectively?

SQS can be used in a number of different ways, but one example of an effective use case is in a message queue system. In this type of system, messages are sent to a queue and then processed by workers in an asynchronous fashion. This can be helpful in ensuring that messages are processed in a timely manner without overloading the system.

19. Are there any costs involved with using SQS? If yes, then what are they?

Yes, there are costs associated with using SQS. These costs can vary depending on the specific use case, but they typically fall into one of three categories: data transfer, request charges, and storage charges. Data transfer costs are incurred when data is transferred in or out of SQS, while request charges are incurred for each API request made to SQS. Finally, storage charges are incurred for each message that is stored in SQS.

20. What are the main differences between SQS and SNS?

The main difference between SQS and SNS is that SQS is a message queue while SNS is a notification service. With SQS, you can store messages in a queue and then process them at your leisure. This is useful if you have a process that can take some time and you don’t want to tie up your main application while it is running. SNS, on the other hand, is designed to send notifications immediately. This can be useful for things like sending text messages or emails in response to events.