PCNE Configuring Network Services Practice Question

An application running on Google Kubernetes Engine (GKE) uses Traffic Director for traffic management with Envoy sidecars. You want to implement fault injection to test resilience by injecting a 50% failure rate on a subset of traffic. Which Traffic Director configuration should you use?

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

Configure a route rule with a fault injection policy specifying a percentage and abort/fixed delay.

Traffic Director uses Envoy's fault injection filter, configured via the Envoy xDS API or through GKE configuration. The correct approach is to apply a traffic policy with fault injection percentage. The other options are not valid Traffic Director features or do not achieve fault injection.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
Use the gcloud compute backend-services update command with the --fault-injection flag.
Why it's wrong here
Fault injection is not configured at the backend service level in gcloud; it's a Traffic Director Envoy route rule.
✗
Set a circuit breaker with a max pending requests threshold.
Why it's wrong here
Circuit breakers prevent cascading failures, but do not inject faults.
✓
Configure a route rule with a fault injection policy specifying a percentage and abort/fixed delay.
Why this is correct
Fault injection is configured in the route rule (via Envoy's fault filter) in Traffic Director.
✗
Create a backend service with connection draining and set the drain timeout.
Why it's wrong here
Connection draining is for graceful shutdown, not fault injection.

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PCNE Configuring Network Services Practice Question

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