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Aws Storage

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85 cards — 🟢 14 easy | 🟡 45 medium | 🔴 20 hard

🟢 Easy (14)

1. Explain what is AWS S3?

Show answer - S3 is a object storage service which is fast, scalable and durable. S3 enables customers to upload, download or store any file or object that is up to 5 TB in size.
- S3 stands for: Simple Storage Service
- As a user you don't have to worry about filesystems or disk space

Name origin: S3 = Simple Storage Service. Object storage with 99.999999999% (11 nines) durability.

Remember: S3 is object storage (key-value), not a filesystem. Objects can be 0 bytes to 5 TB. Use multipart upload for files > 100 MB.

2. What is AWS Guarduty?

Show answer AWS definition: "Amazon GuardDuty is a threat detection service that continuously monitors for malicious activity and unauthorized behavior to protect your Amazon Web Services accounts, workloads, and data stored in Amazon S3"
Monitor VPC Flow lows, DNS logs, CloudTrail S3 events and CloudTrail Mgmt events.

Gotcha: S3 bucket names are globally unique across all AWS accounts. Choose descriptive names with your org prefix to avoid conflicts.

3. What is "Amazon S3 Transfer Acceleration"?

Show answer AWS definition: "Amazon S3 Transfer Acceleration enables fast, easy, and secure transfers of files over long distances between your client and an S3 bucket"

Learn more [here](https://docs.aws.amazon.com/AmazonS3/latest/dev/transfer-acceleration.html)

Name origin: S3 = Simple Storage Service. Object storage with 99.999999999% (11 nines) durability.

Remember: S3 is object storage (key-value), not a filesystem. Objects can be 0 bytes to 5 TB. Use multipart upload for files > 100 MB.

4. What is the difference between stored volumes and cached volumes?

Show answer Stored Volumes - Data is located at customer's data center and periodically backed up to AWS
Cached Volumes - Data is stored in AWS cloud and cached at customer's data center for quick access

Gotcha: S3 bucket names are globally unique across all AWS accounts. Choose descriptive names with your org prefix to avoid conflicts.

5. What is the default EFS mode?

Show answer Performance Mode (General Purpose): Used for web serving, CMS, ... anything that is sensitive to latency.

Remember: EFS = Elastic File System. NFS-compatible, shared across multiple EC2 instances. Auto-scales, pay per GB stored. Think 'shared network drive.'

6. What is a storage class? What storage classes are there?

Show answer Each object has a storage class assigned to, affecting its availability and durability. This also has effect on costs.
Storage classes offered today:
* Standard:
* Used for general, all-purpose storage (mostly storage that needs to be accessed frequently)
* The most expensive storage class
* 11x9% durability
* 2x9% availability
* Default storage class

Remember: S3 tiers by cost (high to low): Standard > Intelligent-Tiering > IA > One Zone-IA > Glacier Instant > Glacier Flexible > Glacier Deep Archive. Access speed decreases as cost decreases.

7. What is AWS Snowmobile?

Show answer AWS Snowmobile is an Exabyte-scale data transfer service used to move extremely large amounts of data to AWS.

Learn more [here](https://aws.amazon.com/snowmobile)

Remember: S3 is eventually consistent for overwrite PUTs and DELETEs (as of 2020, S3 provides strong read-after-write consistency for all operations). This was a major change — older docs may say otherwise.

8. What is AWS Snowball?

Show answer A transport solution which was designed for transferring large amounts of data (petabyte-scale) into and out the AWS cloud.

Remember: S3 is eventually consistent for overwrite PUTs and DELETEs (as of 2020, S3 provides strong read-after-write consistency for all operations). This was a major change — older docs may say otherwise.

9. What is Amazon EFS (Elastic File System) and when would you use it?

Show answer [AWS Docs](https://aws.amazon.com/efs): "Amazon Elastic File System (Amazon EFS) provides a simple, scalable, fully managed elastic NFS file system for use with AWS Cloud services and on-premises resources."

In simpler words, it's a network file system you can mount on one or more EC2 instances.

Remember: EFS = Elastic File System. NFS-compatible, shared across multiple EC2 instances. Auto-scales, pay per GB stored. Think 'shared network drive.'

10. What is AWS Athena and when would you use it for querying data?

Show answer Amazon Athena is an interactive query service that makes it easy to analyze data in Amazon S3 using standard SQL.

Learn more about AWS Athena [here](https://aws.amazon.com/athena)

Remember: S3 is eventually consistent for overwrite PUTs and DELETEs (as of 2020, S3 provides strong read-after-write consistency for all operations). This was a major change — older docs may say otherwise.

11. Explain what is Storage Gateway

Show answer AWS Storage Gateway is a hybrid cloud storage service that gives you on-premises access to virtually unlimited cloud storage.
More on Storage Gateway [here](https://aws.amazon.com/storagegateway)

Remember: S3 is eventually consistent for overwrite PUTs and DELETEs (as of 2020, S3 provides strong read-after-write consistency for all operations). This was a major change — older docs may say otherwise.

12. What is Amazon S3 and what are its key storage features?

Show answer An object storage service that stores data in buckets.

Name origin: S3 = Simple Storage Service. Object storage with 99.999999999% (11 nines) durability.

Remember: S3 is object storage (key-value), not a filesystem. Objects can be 0 bytes to 5 TB. Use multipart upload for files > 100 MB.

13. What is an "EBS Snapshot"?

Show answer An incremental backup of an EBS volume stored in S3.

Remember: EBS = Elastic Block Store. Network-attached block storage for EC2. Think 'virtual hard drive.' Types: gp3 (general), io2 (high IOPS), st1 (throughput), sc1 (cold).

14. What is a bucket in cloud object storage (S3/GCS)?

Show answer An S3 bucket is a resource which is similar to folders in a file system and allows storing objects, which consist of data.

Name origin: S3 = Simple Storage Service. Object storage with 99.999999999% (11 nines) durability.

Remember: S3 is object storage (key-value), not a filesystem. Objects can be 0 bytes to 5 TB. Use multipart upload for files > 100 MB.

🟡 Medium (45)

1. True or False? EFS requires the user to perform capacity planning as it doesn't scales automatically

Show answer False. EFS scales automatically and you pay-per-use.

Remember: EFS = Elastic File System. NFS-compatible, shared across multiple EC2 instances. Auto-scales, pay per GB stored. Think 'shared network drive.'

2. Explain AWS pricing model

Show answer It mainly works on "pay-as-you-go" meaning you pay only for what are using and when you are using it.
In s3 you pay for 1. How much data you are storing 2. Making requests (PUT, POST, ...)
In EC2 it's based on the purchasing option (on-demand, spot, ...), instance type, AMI type and the region used.

More on AWS pricing model [here](https://aws.amazon.com/pricing)

Gotcha: S3 bucket names are globally unique across all AWS accounts. Choose descriptive names with your org prefix to avoid conflicts.

3. If you need an EBS volume for infrequently data access, which volume type would you use?

Show answer Cold HDD (sc1). It's the lowest-cost EBS volume for infrequent access — throughput-optimized at 250 MB/s max, ideal for archival or sequential cold data.

Remember: S3 is eventually consistent for overwrite PUTs and DELETEs (as of 2020, S3 provides strong read-after-write consistency for all operations). This was a major change — older docs may say otherwise.

4. Explain the following Storage Gateway deployments types

Show answer Explained in detail [here](https://aws.amazon.com/storagegateway/faqs)

Remember: S3 storage classes from hot to cold: Standard > Intelligent-Tiering > Standard-IA > One Zone-IA > Glacier Instant > Glacier Flexible > Deep Archive.

Gotcha: S3 charges for storage, requests, and data transfer out. Data transfer IN is free. Optimize costs with lifecycle policies and the right storage class.

5. What Glacier retrieval options are available for the user?

Show answer Expedited, Standard and Bulk

Remember: S3 tiers by cost (high to low): Standard > Intelligent-Tiering > IA > One Zone-IA > Glacier Instant > Glacier Flexible > Glacier Deep Archive. Access speed decreases as cost decreases.

6. What are the use cases for using EBS snapshots?

Show answer * Backups of the data
* Moving the data between AZs

Remember: EBS = Elastic Block Store. Network-attached block storage for EC2. Think 'virtual hard drive.' Types: gp3 (general), io2 (high IOPS), st1 (throughput), sc1 (cold).

7. Explain the concept of AWS Lambda Triggers.

Show answer Lambda Triggers: They're events that invoke Lambda functions automatically when a particular event occurs in other AWS services. For instance, S3 upload triggers a Lambda function.

Remember: S3 is eventually consistent for overwrite PUTs and DELETEs (as of 2020, S3 provides strong read-after-write consistency for all operations). This was a major change — older docs may say otherwise.

8. You would like to have on-perm storage access to AWS storage. What would you use for that?

Show answer Storage Gateway

Remember: S3 storage classes from hot to cold: Standard > Intelligent-Tiering > Standard-IA > One Zone-IA > Glacier Instant > Glacier Flexible > Deep Archive.

Gotcha: S3 charges for storage, requests, and data transfer out. Data transfer IN is free. Optimize costs with lifecycle policies and the right storage class.

9. What are some use cases for using EFS?

Show answer * Data sharing (e.g. developers working on the same source control)
* Web serving
* Content management

Remember: EFS = Elastic File System. NFS-compatible, shared across multiple EC2 instances. Auto-scales, pay per GB stored. Think 'shared network drive.'

10. Explain EBS Snapshots

Show answer EBS snapshots used for making a backup of the EBS volume at point of time.

Remember: S3 is eventually consistent for overwrite PUTs and DELETEs (as of 2020, S3 provides strong read-after-write consistency for all operations). This was a major change — older docs may say otherwise.

11. What EFS storage tiers are there?

Show answer * Standard: frequently accessed files
* Infrequent access: lower prices to store files but it also costs to retrieve them

Remember: EFS = Elastic File System. NFS-compatible, shared across multiple EC2 instances. Auto-scales, pay per GB stored. Think 'shared network drive.'

12. True or False? Buckets are defined globally

Show answer False. They are defined at the region level.

Remember: S3 storage classes from hot to cold: Standard > Intelligent-Tiering > Standard-IA > One Zone-IA > Glacier Instant > Glacier Flexible > Deep Archive.

Gotcha: S3 charges for storage, requests, and data transfer out. Data transfer IN is free. Optimize costs with lifecycle policies and the right storage class.

13. If you need an EBS volume for workloads that require good performance but the cost is also an important aspect for you, which volume type would you use?

Show answer General Purpose SSD (gp2 or gp3). These volumes balance price and performance, delivering up to 16,000 IOPS and 1,000 MB/s throughput (gp3), suitable for boot volumes, dev/test, and most production workloads.

Gotcha: S3 bucket names are globally unique across all AWS accounts. Choose descriptive names with your org prefix to avoid conflicts.

14. If you need an EBS volume for low latency workloads, which volume type would you use?

Show answer Provisioned IOPS SSD (io1 or io2). These volumes are designed for I/O-intensive workloads requiring sustained, low-latency performance — up to 64,000 IOPS and 1,000 MB/s — such as large relational databases and latency-sensitive applications.

Gotcha: S3 bucket names are globally unique across all AWS accounts. Choose descriptive names with your org prefix to avoid conflicts.

15. What would you use to transfer files over long distances between a client and an S3 bucket?

Show answer Amazon S3 Transfer Acceleration

Name origin: S3 = Simple Storage Service. Object storage with 99.999999999% (11 nines) durability.

Remember: S3 is object storage (key-value), not a filesystem. Objects can be 0 bytes to 5 TB. Use multipart upload for files > 100 MB.

16. What encryption types supported by S3?

Show answer * SSE-S3
* SSE-KMS
* SSE-C

Name origin: S3 = Simple Storage Service. Object storage with 99.999999999% (11 nines) durability.

Remember: S3 is object storage (key-value), not a filesystem. Objects can be 0 bytes to 5 TB. Use multipart upload for files > 100 MB.

17. Which EBS volume types can be used as boot volumes for EC2 instances?

Show answer SSD: gp2, gp3, io1, io2

Remember: S3 storage classes from hot to cold: Standard > Intelligent-Tiering > Standard-IA > One Zone-IA > Glacier Instant > Glacier Flexible > Deep Archive.

Gotcha: S3 charges for storage, requests, and data transfer out. Data transfer IN is free. Optimize costs with lifecycle policies and the right storage class.

18. Explain Object Durability and Object Availability

Show answer Object Durability: The percent over a one-year time period that a file will not be lost
Object Availability: The percent over a one-year time period that a file will be accessible

Gotcha: S3 bucket names are globally unique across all AWS accounts. Choose descriptive names with your org prefix to avoid conflicts.

19. Which EFS mode would you use if you need to perform media processing?

Show answer Performance Mode (Max I/O): It provides high throughput and scales to operations per second. Mainly used for big data, media processing, etc.

Remember: EFS = Elastic File System. NFS-compatible, shared across multiple EC2 instances. Auto-scales, pay per GB stored. Think 'shared network drive.'

20. Describe shortly how SSE-S3 (AES) encryption works

Show answer 1. You upload a file to S3 using HTTP (or HTTPS) and header
2. S3 uses the managed data key to encrypt it
3. S3 stores the encrypted object in the bucket

Remember: S3 encryption: SSE-S3 (AWS-managed keys), SSE-KMS (customer-managed via KMS), SSE-C (customer-provided keys). Default encryption is now SSE-S3.

21. What is the AWS Storage Gateway and its use cases?

Show answer Storage Gateway: It's a service connecting an on-premises software appliance with cloud-based storage to provide seamless integration.
Use Cases: Backup, disaster recovery, and hybrid cloud storage are common scenarios. projects/knowledge/interview/aws/443-what-is-the-aws-storage-gateway-and-its-use-cases.txt

Gotcha: S3 bucket names are globally unique across all AWS accounts. Choose descriptive names with your org prefix to avoid conflicts.

22. Explain EC2 hibernate

Show answer [AWS Docs](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/Hibernate.html: "Hibernation saves the contents from the instance memory (RAM) to your Amazon Elastic Block Store (Amazon EBS) root volume."

Remember: S3 is eventually consistent for overwrite PUTs and DELETEs (as of 2020, S3 provides strong read-after-write consistency for all operations). This was a major change — older docs may say otherwise.

23. How many buckets can you create in AWS by default?

Show answer 100 buckets per account.

Remember: S3 storage classes from hot to cold: Standard > Intelligent-Tiering > Standard-IA > One Zone-IA > Glacier Instant > Glacier Flexible > Deep Archive.

Gotcha: S3 charges for storage, requests, and data transfer out. Data transfer IN is free. Optimize costs with lifecycle policies and the right storage class.

24. What are the benefits of using AWS EFS (Elastic File System)?

Show answer EFS: It's a file storage service providing scalable storage for use with Amazon EC2 instances. Benefits include high availability, durability, and compatibility with multiple EC2 instances.

Remember: EFS = Elastic File System. NFS-compatible, shared across multiple EC2 instances. Auto-scales, pay per GB stored. Think 'shared network drive.'

25. What EBS volume types are there?

Show answer * HDD (st 1, sc 1): Low cost HDD volumes
* SSD
* io1, io2: Highest performance SSD
* gp2, gp3: General purpose SSD

Remember: EBS = Elastic Block Store. Network-attached block storage for EC2. Think 'virtual hard drive.' Types: gp3 (general), io2 (high IOPS), st1 (throughput), sc1 (cold).

26. True or False? In case of SSE-S3 (AES-256) encryption, you manage the key

Show answer False. S3 manages the key and uses AES-256 algorithm for the encryption.

Remember: S3 encryption: SSE-S3 (AWS-managed keys), SSE-KMS (customer-managed via KMS), SSE-C (customer-provided keys). Default encryption is now SSE-S3.

27. Which service allows you to transfer large amounts (Petabytes) of data in and out of the AWS cloud?

Show answer AWS Snowball — a physical edge computing and data transfer device that lets you move petabytes of data into or out of AWS. You load data onto the ruggedized appliance on-premises, ship it to AWS, and the data is imported into S3.

Gotcha: S3 bucket names are globally unique across all AWS accounts. Choose descriptive names with your org prefix to avoid conflicts.

28. Explain data consistency

Show answer S3 Data Consistency provides strong read-after-write consistency for PUT and DELETE requests of objects in the S3 bucket in all AWS Regions. S3 always return latest file version.

Remember: S3 is eventually consistent for overwrite PUTs and DELETEs (as of 2020, S3 provides strong read-after-write consistency for all operations). This was a major change — older docs may say otherwise.

29. A customer would like to move data which is rarely accessed from standard storage class to the most cheapest class there is. Which storage class should be used?

Show answer Glacier Deep Archive

Remember: S3 tiers by cost (high to low): Standard > Intelligent-Tiering > IA > One Zone-IA > Glacier Instant > Glacier Flexible > Glacier Deep Archive. Access speed decreases as cost decreases.

30. What's the difference between EBS and S3 in AWS?

Show answer Amazon S3 (Simple Storage Service): It's object storage for files, images, videos, and backups with virtually unlimited storage capacity and internet accessibility.
Amazon EBS (Elastic Block Store): It's block storage used for EC2 instances, behaving like a hard drive. It's more suitable for database storage and allows for snapshots and encryption.

Name origin: S3 = Simple Storage Service. Object storage with 99.999999999% (11 nines) durability.

Remember: S3 is object storage (key-value), not a filesystem. Objects can be 0 bytes to 5 TB. Use multipart upload for files > 100 MB.

31. If you need an EBS volume for high-throughput, which volume type would you use?

Show answer Provisioned IOPS SSD (io1 or io2). These volume types deliver the highest throughput and lowest latency of any EBS option — up to 64,000 IOPS and 1,000 MB/s — ideal for databases and analytics workloads requiring consistent I/O.

Gotcha: S3 bucket names are globally unique across all AWS accounts. Choose descriptive names with your org prefix to avoid conflicts.

32. What are Roles in Kubernetes RBAC and how do they control access?

Show answer [AWS docs](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles.html): "An IAM role is an IAM identity that you can create in your account that has specific permissions...it is an AWS identity with permission policies that determine what the identity can and cannot do in AWS."
For example, you can make use of a role which allows EC2 service to access s3 buckets (read and write).

Gotcha: S3 bucket names are globally unique across all AWS accounts. Choose descriptive names with your org prefix to avoid conflicts.

33. Who or what manages the keys in the case of SSE-KMS encryption?

Show answer The KMS service.

Remember: S3 encryption: SSE-S3 (AWS-managed keys), SSE-KMS (customer-managed via KMS), SSE-C (customer-provided keys). Default encryption is now SSE-S3.

34. Explain different types of volumes in AWS.

Show answer In a cloud office, different types of volumes are like different storage spaces. EBS is like a hard drive, S3 is like a file cabinet, and Glacier is like a secure storage room for long-term archives. Some of them are EBS (Elastic Block Store), S3 (Object Storage), EFS (Elastic File System).

Gotcha: S3 bucket names are globally unique across all AWS accounts. Choose descriptive names with your org prefix to avoid conflicts.

35. True or False? In EBS gp2 volume type, IP will increase if the disk size increases

Show answer True. For gp2 volumes, baseline IOPS scales at 3 IOPS per GB (min 100, max 16,000). A larger disk gets more baseline IOPS. gp3 decouples IOPS from size.

Remember: S3 is eventually consistent for overwrite PUTs and DELETEs (as of 2020, S3 provides strong read-after-write consistency for all operations). This was a major change — older docs may say otherwise.

36. Give an example of architecture or workflow that involves SQS and EC2 & S3

Show answer A website that allows users to upload videos and adds subtitles to them:

1. First the user uploads the video through the web interface which uploads it to an S3 bucket
2. SQS gets notified with a message on the video location
3. EC2 instance (or Lambda function) starts to work on adding the subtitles
4. The video with the subtitles is uploaded to an S3 buckets
5. SQS gets notified of the result and specifically the video location

Gotcha: S3 bucket names are globally unique across all AWS accounts. Choose descriptive names with your org prefix to avoid conflicts.

37. Explain "Multi-part upload"

Show answer [Amazon docs](https://docs.aws.amazon.com/AmazonS3/latest/userguide/mpuoverview.html): "Multipart upload allows you to upload a single object as a set of parts. Each part is a contiguous portion of the object's data...In general, when your object size reaches 100 MB, you should consider using multipart uploads instead of uploading the object in a single operation."

Gotcha: S3 bucket names are globally unique across all AWS accounts. Choose descriptive names with your org prefix to avoid conflicts.

38. What EFS modes are there?

Show answer * Performance mode
* General purpose: used mainly for CMS, web serving, ... as it's optimal for latency sensitive applications
* Max I/O: great for scaling to high levels of throughput and I/O operations per second
* Throughput mode
* Bursting: scale throughput based on FS size
* Provisioned: fixed throughput

Remember: EFS = Elastic File System. NFS-compatible, shared across multiple EC2 instances. Auto-scales, pay per GB stored. Think 'shared network drive.'

39. Describe in high-level the process of creating AMIs

Show answer 1. Start an EC2 instance
2. Customized the EC2 instance (install packages, change OS configuration, etc.)
3. Stop the instance (for avoiding data integrity issues)
4. Create EBS snapshot and build an AMI
5. To verify and test the AMI, launch an instance from the AMI

Gotcha: S3 bucket names are globally unique across all AWS accounts. Choose descriptive names with your org prefix to avoid conflicts.

40. True or False? EFS is locked into a single availability zone

Show answer False. EFS can be mounted across multiple availability zones.

Remember: EFS = Elastic File System. NFS-compatible, shared across multiple EC2 instances. Auto-scales, pay per GB stored. Think 'shared network drive.'

41. Explain the different storage classes in Amazon S3 and their use cases.

Show answer * Standard: General-purpose storage for frequently accessed data.
* Infrequent Access (IA): For less frequently accessed data but requires rapid access when needed.
* Glacier: For long-term archival storage with retrieval times of minutes to hours.

Remember: S3 tiers by cost (high to low): Standard > Intelligent-Tiering > IA > One Zone-IA > Glacier Instant > Glacier Flexible > Glacier Deep Archive. Access speed decreases as cost decreases.

42. Explain "Object Versioning"

Show answer When enabled at a bucket level, versioning allows you to upload new version of files, overriding previous version and so be able to easily roll-back and protect your data from being permanently deleted.

Remember: S3 versioning preserves every version of every object. Delete adds a 'delete marker' — the object is recoverable. Combine with lifecycle rules to manage costs.

43. What is Amazon EBS (Elastic Block Store) and when would you use it?

Show answer [AWS Docs](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/AmazonEBS.html): "provides block level storage volumes for use with EC2 instances. EBS volumes behave like raw, unformatted block devices."

Remember: EBS = Elastic Block Store. Network-attached block storage for EC2. Think 'virtual hard drive.' Types: gp3 (general), io2 (high IOPS), st1 (throughput), sc1 (cold).

44. How to host static website in AWS ?

Show answer Host a static website on AWS using Amazon S3. Upload your files to an S3 bucket and enable static website hosting in the bucket properties.

Remember: S3 is eventually consistent for overwrite PUTs and DELETEs (as of 2020, S3 provides strong read-after-write consistency for all operations). This was a major change — older docs may say otherwise.

45. What is the maximum size of an individual S3 object?

Show answer 5 Terabytes (TB).

Name origin: S3 = Simple Storage Service. Object storage with 99.999999999% (11 nines) durability.

Remember: S3 is object storage (key-value), not a filesystem. Objects can be 0 bytes to 5 TB. Use multipart upload for files > 100 MB.

🔴 Hard (20)

1. Why would someone choose to use SSE-KMS instead of SSE-S3?

Show answer SSE-KMS provides control over who has access to the keys and you can also enabled audit trail.

Remember: S3 is eventually consistent for overwrite PUTs and DELETEs (as of 2020, S3 provides strong read-after-write consistency for all operations). This was a major change — older docs may say otherwise.

2. What are some limitations of EC2 hibernate option?

Show answer * Instance RAM size is limited
* Root volume must be encrypted EBS
* Hibernation time is limited
* Doesn't supports all instances types
* No support for bare metal. Only On-Demand and Reserved instances
* Doesn't supports all AMIs

Gotcha: S3 bucket names are globally unique across all AWS accounts. Choose descriptive names with your org prefix to avoid conflicts.

3. True or False? In case of SSE-C HTTPS must be used and encryption key must be provided in headers for every HTTP request

Show answer True. With SSE-C (Server-Side Encryption with Customer-Provided Keys), you must use HTTPS and include the encryption key in the request headers for every S3 operation.

Remember: S3 encryption: SSE-S3 (AWS-managed keys), SSE-KMS (customer-managed via KMS), SSE-C (customer-provided keys). Default encryption is now SSE-S3.

4. What would you use for running SQL queries interactively on S3?

Show answer Amazon Athena. It runs standard SQL queries directly against data in S3 (CSV, JSON, Parquet, ORC) using a serverless Presto engine — no infrastructure to manage, pay per query.

Name origin: S3 = Simple Storage Service. Object storage with 99.999999999% (11 nines) durability.

Remember: S3 is object storage (key-value), not a filesystem. Objects can be 0 bytes to 5 TB. Use multipart upload for files > 100 MB.

5. What if I have lost the Pem file for ubuntu user of an ec2-instance ?

Show answer It's advisable to create a new key pair and associate it with the instance. Otherwise, if an EBS-backed instance, stopping it, detaching the root volume, attaching it to another instance, modifying the authorized_keys file, then reattaching it to the original instance might help recover access.

Gotcha: S3 bucket names are globally unique across all AWS accounts. Choose descriptive names with your org prefix to avoid conflicts.

6. You try to use an detached EBS volume from us-east-1b in us-east-1a, but it fails. What might be the reason?

Show answer EBS volumes are locked to a specific availability zone. To use them in another availability zone, you need to take a snapshot and restore it in the destination availability zone.

Remember: EBS = Elastic Block Store. Network-attached block storage for EC2. Think 'virtual hard drive.' Types: gp3 (general), io2 (high IOPS), st1 (throughput), sc1 (cold).

7. Can you host dynamic websites on S3? What about static websites?

Show answer No. S3 support only statis hosts. On a static website, individual webpages include static content. They might also contain client-side scripts. By contrast, a dynamic website relies on server-side processing, including server-side scripts such as PHP, JSP, or ASP.NET. Amazon S3 does not support server-side scripting.

Name origin: S3 = Simple Storage Service. Object storage with 99.999999999% (11 nines) durability.

Remember: S3 is object storage (key-value), not a filesystem. Objects can be 0 bytes to 5 TB. Use multipart upload for files > 100 MB.

8. How to rename a bucket in S3?

Show answer A S3 bucket name is immutable. That means it's not possible to change it, without removing and creating a new bucket.

This is why the process for renaming a bucket is as follows:

* Create a new bucket with the desired name
* Move the data from the old bucket to it
* Delete the old bucket

With the AWS CLI that would be:

```sh\n# Create new bucket\naws s3 mb s3://[NEW_BUCKET_NAME]\n# Sync the content from the old bucket to the new bucket\n$ aws s3 sync s3://[OLD_BUCKET_NAME] s3://[NEW_BUCKET_NAME]\n# Remove old bucket\n$ aws s3 rb --force s3://[OLD_BUCKET_NAME]\n```

9. Describe shortly how SSE-C encryption works

Show answer 1. User uploads a file to S3 using HTTPS while providing data key in the header
2. AWS S3 performs the encryption using the provided data key and encrypted object is stored in the bucket

If a user would like to get the object, the same data key would have to be provided.

Remember: S3 encryption: SSE-S3 (AWS-managed keys), SSE-KMS (customer-managed via KMS), SSE-C (customer-provided keys). Default encryption is now SSE-S3.

10. True or False? In case of SSE-C encryption, both S3 and you manage the keys

Show answer False. You manage the keys. It's customer provided keys.

Remember: S3 encryption: SSE-S3 (AWS-managed keys), SSE-KMS (customer-managed via KMS), SSE-C (customer-provided keys). Default encryption is now SSE-S3.

11. A user is unable to access an s3 bucket. What might be the problem?

Show answer There can be several reasons for that. One of them is lack of policy. To solve that, the admin has to attach the user with a policy what allows him to access the s3 bucket.

Name origin: S3 = Simple Storage Service. Object storage with 99.999999999% (11 nines) durability.

Remember: S3 is object storage (key-value), not a filesystem. Objects can be 0 bytes to 5 TB. Use multipart upload for files > 100 MB.

12. What happens to EBS volumes when the instance is terminated?

Show answer By default, the root volume is marked for deletion, while other volumes will still remain.
You can control what will happen to every volume upon termination.

Remember: EBS = Elastic Block Store. Network-attached block storage for EC2. Think 'virtual hard drive.' Types: gp3 (general), io2 (high IOPS), st1 (throughput), sc1 (cold).

13. How to encrypt an unencrypted EBS volume attached to an EC2 instance?

Show answer 1. Create EBS snapshot of the volume
2. Copy the snapshot and mark the "Encrypt" option
3. Create a new EBS volume out of the encrypted snapshot

Remember: S3 is eventually consistent for overwrite PUTs and DELETEs (as of 2020, S3 provides strong read-after-write consistency for all operations). This was a major change — older docs may say otherwise.

14. True or False? Every new S3 bucket is public by default

Show answer False. A newly created bucket is private unless it was configured to be public.

Remember: S3 is eventually consistent for overwrite PUTs and DELETEs (as of 2020, S3 provides strong read-after-write consistency for all operations). This was a major change — older docs may say otherwise.

15. How to recover an ec2-instance if it crashes ?

Show answer Depends on the type of instance and its stored data. For EBS-backed instances, the data persists on the EBS volume and can be attached to another instance. For instance store-backed instances, recovery would involve relaunching the instance, losing any non-persistent data.

Gotcha: S3 bucket names are globally unique across all AWS accounts. Choose descriptive names with your org prefix to avoid conflicts.

16. What security measures have you taken in context of S3?

Show answer * Don't make a bucket public.
* Enable encryption if it's disabled.
* Define an access policy

Name origin: S3 = Simple Storage Service. Object storage with 99.999999999% (11 nines) durability.

Remember: S3 is object storage (key-value), not a filesystem. Objects can be 0 bytes to 5 TB. Use multipart upload for files > 100 MB.

17. You try to mount EFS on your EC2 instance and it doesn't work (hangs...) What might be a possible reason?

Show answer Security group isn't attached to your EFS or it lacks a rule to allow NFS traffic.

Remember: EFS = Elastic File System. NFS-compatible, shared across multiple EC2 instances. Auto-scales, pay per GB stored. Think 'shared network drive.'

18. How to migrate an EBS volume across availability zones?

Show answer 1. Pause the application
2. Take a snapshot of the EBS volume
3. Restore the snapshot in another availability zone

Remember: S3 is eventually consistent for overwrite PUTs and DELETEs (as of 2020, S3 provides strong read-after-write consistency for all operations). This was a major change — older docs may say otherwise.

19. What's a presigned URL?

Show answer Since every newly created bucket is by default private it doesn't allows to share files with users. Even if the person who uploaded them tries to view them, it gets denied.

A presigned URL is a way to bypass that and allow sharing the files with users by including the credentials (token) as part of the URL. It can be done for limited time.

Remember: presigned URLs grant temporary access to private S3 objects. The URL includes the signature and expiry. Use for secure file sharing without making objects public.

20. Is it possible to attach the same EBS volume to multiple EC2 instances?

Show answer Yes, with multi-attach it's possible to attach a single EBS volume to multiple instances.

Remember: S3 is eventually consistent for overwrite PUTs and DELETEs (as of 2020, S3 provides strong read-after-write consistency for all operations). This was a major change — older docs may say otherwise.