An orders service currently sends HTTP requests directly to two downstream services (inventory and shipping). During peak load, inventory slows down, causing the orders service to slow as well. The team wants the orders service to remain responsive even when a downstream service is temporarily slow or restarted. Which design change best achieves this resiliency goal?

Keep HTTP calls but add longer client timeouts so orders requests wait for slow downstream responses.

Longer timeouts increase how long the orders service waits on downstream dependency. Under slow or failing downstream behavior, this can still tie up resources (threads/connection pools) and reduce the orders service’s responsiveness.

Replace the downstream services with AWS Lambda functions that are invoked synchronously by the orders service.

Synchronous invocation keeps the dependency chain. If a Lambda function or its downstream dependencies slow down, the orders service still waits and experiences coupled latency.

Call the downstream services in parallel threads to reduce waiting time during peak load.

Parallel calls may reduce response time briefly, but it does not eliminate the coupling to downstream availability/latency. If inventory is slow, parallelism still consumes resources and can degrade overall responsiveness under sustained load or failures.

What does this SAA-C03 question test?

Read the scenario before looking for a memorised answer.

What is the correct answer to this question?

The correct answer is: Introduce Amazon SQS as a buffer between orders and downstream services, with consumers processing from the queue. — Use an asynchronous messaging buffer to decouple request handling from downstream processing. By placing an Amazon SQS queue between the orders service and downstream consumers, the orders service enqueues work quickly and does not have to wait for inventory/shipping to complete. When inventory slows down or restarts, messages remain available in the queue, and consumers can process them when they recover. This prevents cascading failures and helps keep the public orders API responsive during downstream disruptions. Longer timeouts (A) still make orders depend on downstream response times and can exhaust resources. Synchronous Lambda calls (C) do not remove the dependency chain and still couple latency. Parallelism (D) may hide latency in short bursts but does not provide buffering to absorb downstream slowdowns.

What should I do if I get this SAA-C03 question wrong?

Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.