Microservices Resilience and Fault Tolerance 2

Question 1

In a circuit breaker, what does the HALF-OPEN state primarily do?

Accepted Answer

Allows a limited number of trial requests to test if the service has recovered

Answer

HALF-OPEN lets a few probe requests through to determine whether the downstream service has recovered before fully closing the circuit.

Question 2

What is the main purpose of the bulkhead pattern in microservices?

Accepted Answer

Isolating resources so a failure in one component cannot exhaust resources used by others

Answer

The bulkhead pattern partitions resources (like thread pools) so one failing dependency cannot bring down the entire service.

Question 3

Which retry strategy adds randomness to wait times to avoid synchronized retry storms?

Accepted Answer

Exponential backoff with jitter

Answer

Jitter randomizes backoff intervals so many clients do not all retry at the exact same moment, preventing thundering-herd load spikes.

Question 4

A timeout is set too high on a downstream call. What resilience risk does this create?

Accepted Answer

Threads and connections stay occupied longer, risking resource exhaustion under load

Answer

Overly long timeouts tie up threads and connections, allowing a slow dependency to cascade into resource starvation.

Question 5

What does graceful degradation mean for a microservice under partial failure?

Accepted Answer

The service continues providing reduced or fallback functionality instead of failing entirely

Answer

Graceful degradation delivers a reduced experience (e.g., cached or default data) rather than a total outage when a dependency fails.

Microservices Practice Test