Aws s3 Interview Questions​

Basic Aws s3 Interview Questions

1. What is Amazon S3?
   Amazon Simple Storage Service (S3) is an object storage service that allows users to store and retrieve large amounts of data securely in the cloud.
2. What are the main features of Amazon S3?
   • Scalability
   • High durability (99.999999999% durability)
   • Multiple storage classes
   • Versioning
   • Encryption
   • Lifecycle policies
   • Cross-region replication
3. How does Amazon S3 store data?
   S3 stores data as objects within buckets. Each object consists of data, metadata, and a unique key.
4. What is an S3 bucket?
   A bucket is a logical container in S3 where objects (files) are stored. Each AWS account can create multiple buckets.
5. How is data organized in S3?
   Data in S3 is stored in a flat structure, without hierarchical folders. However, folders can be simulated using prefixes in object keys.
6. What is the difference between an S3 bucket and an object?
   A bucket is a container for objects, while an object is the actual file stored in S3, including metadata and permissions.
7. How does S3 ensure data durability and availability?
   S3 stores multiple copies of data across different Availability Zones (AZs) to ensure 99.999999999% (11 9s) durability.
8. What is the default storage class in S3?
   S3 Standard is the default storage class, designed for frequently accessed data.
9. What are the different storage classes in S3?
   • S3 Standard
   • S3 Intelligent-Tiering
   • S3 Standard-IA (Infrequent Access)
   • S3 One Zone-IA
   • S3 Glacier
   • S3 Glacier Deep Archive
10. How does versioning work in S3?
    Versioning allows multiple versions of an object to be stored, preventing accidental deletions or overwrites.
11. What is S3 Transfer Acceleration?
    A feature that speeds up uploads by routing traffic through AWS edge locations.
12. What is the maximum size of an object that can be uploaded in a single PUT request?
    5 GB.
13. How can large objects be uploaded to S3?
    Using Multipart Upload, which splits large files into smaller parts.
14. How does S3 handle object deletions?
    • Soft delete (with versioning enabled, it keeps old versions)
    • Hard delete (permanent deletion if versioning is disabled)
15. What is the difference between S3 Glacier and S3 Glacier Deep Archive?
    • S3 Glacier: Retrieval times of minutes to hours.
    • S3 Glacier Deep Archive: Cheapest storage, but retrieval takes 12+ hours.

Security & Access Control

16. How do you control access to an S3 bucket?
    • IAM policies
    • Bucket policies
    • Access Control Lists (ACLs)
    • Pre-signed URLs
17. What are S3 bucket policies?
    JSON-based policies that define permissions for the entire bucket.
18. What are S3 access control lists (ACLs)?
    ACLs define permissions at the object or bucket level, allowing access to specific AWS accounts.
19. What is IAM and how is it used with S3?
    IAM (Identity and Access Management) controls user access to AWS resources, including S3.
20. What is an S3 presigned URL?
    A temporary URL that allows secure access to an S3 object without requiring AWS credentials.
21. How can you encrypt data stored in S3?
    • Server-Side Encryption (SSE)
    • Client-Side Encryption
22. What are the different types of encryption in S3?
    • SSE-S3 (managed by AWS)
    • SSE-KMS (AWS KMS-managed keys)
    • SSE-C (Customer-managed keys)
    • Client-side encryption
23. How does AWS KMS integrate with S3 encryption?
    AWS KMS manages encryption keys used for SSE-KMS encryption.
24. How does S3 Object Lock work?
    Prevents deletion of objects for a specified period (Compliance/WORM storage).
25. What is S3 Block Public Access?
    A feature that blocks all public access to an S3 bucket.

Performance & Optimization

26. How can you optimize the performance of S3?
    • Enable Transfer Acceleration
    • Use Multipart Upload for large files
    • Use S3 Select to filter data
27. What is Amazon S3 Intelligent-Tiering?
    A storage class that automatically moves objects between frequent and infrequent access tiers.
28. How does multipart upload work in S3?
    It splits large files into smaller parts, uploading them in parallel.
29. What is request rate and performance optimization in S3?
    S3 supports thousands of requests per second but can be optimized using randomized prefixes.
30. What are lifecycle policies in S3?
    Rules that automatically transition or delete objects after a set time.
31. How does S3 replication work?
    Replicates objects between buckets for backup or compliance.
32. What are the differences between Cross-Region Replication (CRR) and Same-Region Replication (SRR)?
    • CRR: Replicates data across different AWS regions.
    • SRR: Replicates within the same region.
33. What is S3 Select and how does it improve performance?
    Allows SQL queries on objects, reducing data retrieval time.
34. How does Amazon Athena work with S3?
    Athena is a query service that runs SQL queries on S3 data.
35. What is the difference between S3 Standard and S3 Standard-IA?
    S3 Standard is for frequent access, while S3 Standard-IA is for infrequent access with lower cost.

Cost & Billing

36. How is Amazon S3 pricing structured?
    Based on storage, requests, and data transfer.
37. What factors affect S3 storage costs?
    • Storage class
    • Data retrieval fees
    • Number of requests
    • Data transfer
38. How can you reduce S3 storage costs?
    • Use lifecycle policies
    • Move data to Glacier
    • Delete unused objects
39. What is S3 Object Expiration?
    Automatically deletes objects after a set period.
40. How does S3 request pricing work?
    Charges per GET, PUT, COPY, and LIST requests.
41. What are data transfer costs in S3?
    • Inbound transfer is free.
    • Outbound transfer incurs charges.
42. What is the AWS Free Tier limit for S3?
    • 5GB of Standard Storage
    • 20,000 GET requests

Advanced Features & Integrations

43. What is Amazon S3 Event Notification?
    Triggers notifications for events like object creation or deletion.
44. How do you integrate AWS Lambda with S3?
    Use S3 Event Notifications to trigger Lambda functions.
45. What is S3 Inventory?
    Provides a report of objects stored in a bucket.
46. What is S3 Access Analyzer?
    Identifies and fixes unintended public access.
47. How does AWS CloudTrail work with S3?
    Logs S3 API calls for auditing.
48. How do you migrate data from on-premises storage to S3?
    • AWS DataSync
    • AWS Snowball
49. What is the role of AWS Storage Gateway with S3?
    Bridges on-premises storage and S3.
50. How does Amazon S3 integrate with AWS Glue?
    AWS Glue extracts, transforms, and loads (ETL) data from S3.

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