Cross-region replication (Global Tables) in DynamoDB - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

How does DynamoDB Global Tables handle data replication?

Which statement best describes how DynamoDB Global Tables replicate data across regions?

A Data is asynchronously replicated between regions with eventual consistency.

B Data is synchronously replicated with strong consistency across all regions.

C Data replication happens only when manually triggered by the user.

D Data is replicated only for read operations, not writes.

💡 Hint

Think about how DynamoDB balances latency and consistency in global replication.

DynamoDB Global Tables use asynchronous replication to ensure low latency writes in each region while achieving eventual consistency across regions.

❓ query_result

intermediate

Result of a write conflict in DynamoDB Global Tables

Given two concurrent writes to the same item in different regions, what is the expected outcome in DynamoDB Global Tables?

A The write in the primary region always overwrites the other.

B An error is returned to the client indicating a conflict.

C Both writes are merged automatically without conflicts.

D The last write based on timestamp wins and overwrites the other.

💡 Hint

Consider how DynamoDB resolves conflicts using timestamps.

DynamoDB Global Tables resolve conflicts by using a last-writer-wins approach based on timestamps, so the most recent write overwrites the other.

📝 Syntax

advanced

Identify the error in creating a Global Table

Which option contains a valid AWS CLI command to create a DynamoDB Global Table with two regions?

DynamoDB

aws dynamodb create-global-table --global-table-name MyGlobalTable --replication-group RegionName=us-east-1 RegionName=eu-west-1

A aws dynamodb create-global-table --global-table-name MyGlobalTable --replication-group '[{"RegionName":"us-east-1"},{"RegionName":"eu-west-1"}]'

B aws dynamodb create-global-table --global-table-name MyGlobalTable --replication-group RegionName=us-east-1 RegionName=eu-west-1

C aws dynamodb create-global-table --global-table-name MyGlobalTable --replication-group RegionName=us-east-1,RegionName=eu-west-1

D aws dynamodb create-global-table --global-table-name MyGlobalTable --replication-group '[RegionName=us-east-1,RegionName=eu-west-1]'

💡 Hint

Check the correct JSON format for the replication group parameter.

The replication group must be passed as a JSON array string with objects specifying each region.

❓ optimization

advanced

Optimizing read latency with Global Tables

You want to minimize read latency for users in multiple regions using DynamoDB Global Tables. Which strategy is best?

A Always read from the us-east-1 region regardless of user location.

B Direct reads to the nearest regional replica of the Global Table.

C Use a single region Global Table and replicate data manually.

D Disable Global Tables and use local tables with periodic batch sync.

💡 Hint

Think about how Global Tables distribute data for low latency.

Global Tables replicate data to multiple regions, so directing reads to the closest replica reduces latency.

🔧 Debug

expert

Diagnosing replication lag in DynamoDB Global Tables

You notice that updates made in one region are not appearing promptly in another region's replica. Which is the most likely cause?

A Strong consistency setting enabled causing replication to block.

B Writes are being rejected due to exceeding provisioned throughput.

C Network issues causing delayed asynchronous replication.

D Global Table is configured with only one region.

💡 Hint

Consider how replication works and what can delay it.

Replication in Global Tables is asynchronous; network delays can cause lag in data propagation between regions.