AWS Certified Solutions Architect – Professional — Question 219

While debugging a backend application for an IoT system that supports globally distributed devices, a Solutions Architect notices that stale data is occasionally being sent to user devices. Devices often share data, and stale data does not cause issues in most cases. However, device operations are disrupted when a device reads the stale data after an update.
The global system has multiple identical application stacks deployed in different AWS Regions. If a user device travels out of its home geographic region, it will always connect to the geographically closest AWS Region to write or read data. The same data is available in all supported AWS Regions using an Amazon
DynamoDB global table.
What change should be made to avoid causing disruptions in device operations?

Answer options

• A. Update the backend to use strongly consistent reads. Update the devices to always write to and read from their home AWS Region.
• B. Enable strong consistency globally on a DynamoDB global table. Update the backend to use strongly consistent reads.
• C. Switch the backend data store to Amazon Aurora MySQL with cross-region replicas. Update the backend to always write to the master endpoint.
• D. Select one AWS Region as a master and perform all writes in that AWS Region only. Update the backend to use strongly consistent reads.

Correct answer: A

Explanation

The correct answer is A because using strongly consistent reads ensures that devices always retrieve the most current data, thus avoiding issues with stale data after updates. The other options either do not address the need for strong consistency effectively or complicate the system by introducing unnecessary architecture changes, which may not resolve the core issue of stale data.