Linkerd Traffic Management Quiz
This quiz tests your understanding of Linkerd traffic management.
Quiz Questions
1. What cannot be configured per-route in a ServiceProfile?
A. Timeout B. Retryability C. Load balancer algorithm D. Path condition
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Answer: C. Load balancer algorithm
Explanation: ServiceProfile can configure timeout, retryability (isRetryable), and path conditions (method, pathRegex) per route. The load balancer algorithm is a Linkerd global setting, using EWMA.
2. What load balancing algorithm does Linkerd use?
A. Round Robin B. Least Connections C. EWMA (Exponentially Weighted Moving Average) D. Random
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Answer: C. EWMA (Exponentially Weighted Moving Average)
Explanation: Linkerd uses the EWMA algorithm to prefer endpoints with faster response latency. It adapts to endpoint state in real-time and automatically reduces traffic to slow endpoints.
3. What standard specification does TrafficSplit follow?
A. CNCF B. SMI (Service Mesh Interface) C. OpenAPI D. gRPC
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Answer: B. SMI (Service Mesh Interface)
Explanation: TrafficSplit is a CRD that follows the SMI (Service Mesh Interface) standard. SMI defines common interfaces for service meshes to provide compatibility between different mesh implementations.
4. What does a retryBudget retryRatio of 0.2 mean?
A. Only 20% of all requests are retried B. Only 20% of failed requests are retried C. Up to 20% additional retries allowed relative to original requests D. Retry budget resets every 20 seconds
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Answer: C. Up to 20% additional retries allowed relative to original requests
Explanation: A retryRatio of 0.2 allows up to 20% additional retries relative to the original number of requests. Example: Up to 20 additional retries allowed for 100 requests. This prevents overload from retries.
5. Which is NOT a method to auto-generate a ServiceProfile?
A. Generate from OpenAPI/Swagger spec B. Generate from live traffic tap C. Generate from Protobuf definition D. Auto-generate from Kubernetes Service
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Answer: D. Auto-generate from Kubernetes Service
Explanation: ServiceProfiles can be generated using linkerd profile --open-api, linkerd viz profile --tap, and linkerd profile --proto commands. They are not auto-generated from Kubernetes Services and must be explicitly defined.
6. What should the sum of TrafficSplit backend weights be for canary deployment?
A. Must be exactly 100 B. Must be exactly 1 C. Any value works (calculated as ratio) D. Must be exactly 1000
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Answer: C. Any value works (calculated as ratio)
Explanation: TrafficSplit weights are calculated as relative ratios. weight: 90 and weight: 10 is equivalent to weight: 9 and weight: 1. The sum doesn't need to be 100.
7. What routing condition is NOT supported in HTTPRoute (Gateway API)?
A. Header-based routing B. Path-based routing C. Cookie-based routing D. Source IP-based routing
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Answer: D. Source IP-based routing
Explanation: HTTPRoute supports header, path, method, and cookie (via headers) based routing. Source IP-based routing is outside the scope of L7 routing and is handled by NetworkPolicy or other mechanisms.
8. What metrics server is used when integrating Flagger with Linkerd?
A. Metrics Server B. Prometheus C. InfluxDB D. Datadog
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Answer: B. Prometheus
Explanation: Flagger retrieves metrics (success rate, latency, etc.) from Linkerd Viz's Prometheus for canary analysis. When installing Flagger, connect with --set metricsServer=http://prometheus.linkerd-viz:9090.
9. What happens on a route where ServiceProfile isRetryable is false?
A. All requests fail B. No retries occur C. Timeouts are ignored D. Route is disabled
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Answer: B. No retries occur
Explanation: isRetryable: false means requests on that route will not be retried even if they fail. This is suitable for non-idempotent operations like POST requests. The request itself is processed normally.
10. How is the Circuit Breaker pattern implemented in Linkerd?
A. Circuit Breaker CRD B. Failure Accrual C. Rate Limiter D. Timeout Policy
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Answer: B. Failure Accrual
Explanation: Linkerd implements the circuit breaker pattern through failure accrual. On consecutive failures, it temporarily excludes the endpoint, retries with exponential backoff, and returns to normal state on success.
11. How do you send traffic to a mirror service without traffic splitting?
A. Use TrafficMirror CRD B. Call mirror service DNS directly C. All traffic is automatically mirrored D. Linkerd doesn't support traffic mirroring
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Answer: B. Call mirror service DNS directly
Explanation: Linkerd itself doesn't have traffic mirroring functionality like Istio. Multi-cluster mirror services (e.g., web-west) must be called directly via DNS or configured with TrafficSplit weights.
12. What happens on a route where ServiceProfile timeout is not set?
A. Default 5-second timeout applies B. No timeout (unlimited) C. Request fails immediately D. Global timeout applies
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Answer: B. No timeout (unlimited)
Explanation: Routes without a timeout specified in ServiceProfile wait indefinitely without timeout. This is suitable for streaming or long-running operations, but explicitly setting timeouts is generally recommended.