Buckets and objects concept in AWS - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

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

You upload a file named report.pdf to an Amazon S3 bucket. The bucket already contains an object with the key report.pdf. What will happen to the existing object?

A The existing object is overwritten by the new upload.

B The new object is stored with a different key automatically.

C Both objects are stored with the same key, creating duplicates.

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

💡 Hint

Think about how S3 handles object keys as unique identifiers.

In Amazon S3, object keys are unique within a bucket. Uploading an object with an existing key replaces the old object with the new one.

❓ Architecture

intermediate

How to design a bucket policy to allow read-only access to all objects for anonymous users?

You want to allow anyone on the internet to read objects from your S3 bucket named public-assets without requiring authentication. Which bucket policy snippet correctly grants this permission?

A { "Effect": "Allow", "Principal": "*", "Action": "s3:PutObject", "Resource": "arn:aws:s3:::public-assets/*" }

B { "Effect": "Allow", "Principal": {"AWS": "*"}, "Action": "s3:ListBucket", "Resource": "arn:aws:s3:::public-assets" }

C { "Effect": "Deny", "Principal": "*", "Action": "s3:GetObject", "Resource": "arn:aws:s3:::public-assets/*" }

D { "Effect": "Allow", "Principal": "*", "Action": "s3:GetObject", "Resource": "arn:aws:s3:::public-assets/*" }

💡 Hint

Focus on the action that allows reading objects and the resource path.

The s3:GetObject action allows reading objects. The resource must specify the bucket and all objects inside it using /*. The principal * means anyone.

❓ service_behavior

advanced

What is the behavior of S3 when you delete a versioned object without specifying a version ID?

Your S3 bucket has versioning enabled. You delete an object named data.csv without specifying a version ID. What happens to the object?

A A delete marker is added, making the latest version invisible but older versions remain.

B The delete operation fails because version ID is required.

C The latest version is permanently deleted, and older versions remain accessible.

D All versions of the object are permanently deleted immediately.

💡 Hint

Consider how versioning handles deletions without version IDs.

When versioning is enabled, deleting an object without a version ID adds a delete marker as the latest version. This hides the object but keeps all previous versions intact.

❓ security

advanced

Which S3 bucket configuration prevents public access to all objects regardless of bucket policy?

You want to ensure that no objects in your S3 bucket can be accessed publicly, even if a bucket policy or ACL grants public permissions. Which setting achieves this?

A Set the bucket ACL to 'public-read'.

B Remove all IAM user permissions for the bucket.

C Enable 'Block all public access' in the bucket's Public Access Settings.

D Create a bucket policy that allows public read access.

💡 Hint

Think about the global setting that overrides other permissions.

Enabling 'Block all public access' prevents any public access regardless of bucket policies or ACLs. This is the strongest way to block public access.

✅ Best Practice

expert

What is the recommended way to organize objects in a large S3 bucket for efficient performance and cost management?

You have a bucket storing millions of objects. You want to optimize for fast retrieval and cost efficiency. Which approach is best?

A Create a separate bucket for each object to isolate storage.

B Use prefixes (folder-like paths) to distribute objects evenly and enable lifecycle policies on prefixes.

C Store all objects at the root level without prefixes to simplify access.

D Disable versioning to reduce storage costs regardless of object organization.

💡 Hint

Think about how S3 handles object keys and lifecycle rules.

Using prefixes helps S3 distribute load and improves performance. Lifecycle policies can be applied to prefixes to manage costs by archiving or deleting old objects.