Uploading and downloading objects in AWS - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ service_behavior

intermediate

What happens when you upload an object with the same key to an S3 bucket?

You upload a file named report.pdf to an Amazon S3 bucket. Later, you upload another file with the same name report.pdf to the same bucket. What is the result?

A The bucket creates a version of the file but keeps both accessible by default.

B The upload fails with an error because the key already exists.

C The new file overwrites the existing file with the same key.

D Both files are stored separately with different keys automatically.

💡 Hint

Think about how S3 handles object keys and overwriting.

In Amazon S3, object keys are unique within a bucket. Uploading an object with the same key replaces the existing object. Versioning must be enabled to keep multiple versions.

❓ Configuration

intermediate

Which AWS CLI command downloads an object from S3 to your local machine?

You want to download the file image.png from the S3 bucket my-bucket to your current local directory using AWS CLI. Which command is correct?

A aws s3 get-object my-bucket image.png ./

B aws s3 download s3://my-bucket/image.png ./

C aws s3 fetch s3://my-bucket/image.png ./

D aws s3 cp s3://my-bucket/image.png ./

💡 Hint

Look for the AWS CLI command that copies files between S3 and local.

The aws s3 cp command copies files between S3 and your local system. The other commands are invalid or do not exist.

❓ Architecture

advanced

How to design a secure upload system for user files to S3 with minimal permissions?

You want users to upload files directly to an S3 bucket without exposing your AWS credentials or giving full bucket access. Which approach is best?

A Generate pre-signed URLs for upload with limited time and permissions.

B Give users IAM user credentials with full S3 bucket access.

C Allow public write access on the S3 bucket so users can upload freely.

D Use AWS Lambda to upload files on behalf of users with admin permissions.

💡 Hint

Think about temporary, limited access for uploads without exposing credentials.

Pre-signed URLs allow users to upload files directly to S3 with limited permissions and expiration, improving security and reducing complexity.

❓ security

advanced

What is the effect of enabling S3 bucket versioning on object uploads and deletions?

You enable versioning on an S3 bucket. What happens when you upload a new object with the same key or delete an object?

A New uploads overwrite existing objects; deletions permanently remove the object.

B New uploads create new versions; deletions add a delete marker without removing versions.

C New uploads fail if the key exists; deletions are disabled.

D New uploads create copies with different keys; deletions archive the object.

💡 Hint

Consider how versioning preserves object history.

With versioning enabled, each upload creates a new version. Deleting an object adds a delete marker but does not remove previous versions, allowing recovery.

✅ Best Practice

expert

Which method optimizes large file uploads to S3 for reliability and performance?

You need to upload a 10 GB video file to S3. Which method is best to ensure efficient upload and recovery from failures?

A Use multipart upload to upload parts in parallel and retry failed parts.

B Upload the entire file in a single <code>put-object</code> request.

C Split the file manually and upload each part as a separate object.

D Compress the file and upload it using the AWS CLI <code>sync</code> command.

💡 Hint

Think about handling large files and network interruptions.

Multipart upload splits large files into parts uploaded in parallel. It allows retrying failed parts without restarting the entire upload, improving reliability and speed.