The answer is Istio or Anthos Service Mesh, Google Cloud Load Balancer, and Envoy sidecar proxies. These three components work together to enable canary deployment traffic splitting on GKE by leveraging Envoy as a sidecar proxy within the mesh to intercept and route a defined percentage of gRPC traffic to different service versions based on weight or HTTP headers, while the Google Cloud Load Balancer handles external ingress and integrates with the mesh for consistent routing policies. On the Google Professional Cloud Developer exam, this scenario tests your understanding of service mesh traffic management versus simpler Ingress-based splitting, often appearing as a multiple-select question where a common trap is choosing only GCLB and Ingress without the mesh layer. Remember the mnemonic "MEL" for Mesh, Envoy, Load Balancer—without the mesh, you lose fine-grained, application-layer control for canary rollouts.
PCD Practice Question: Designing highly scalable, available, and reliable cloud-native applications
This PCD practice question tests your understanding of designing highly scalable, available, and reliable cloud-native applications. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company runs a microservices architecture on GKE with gRPC services. They want to implement traffic splitting for canary deployments. Which THREE components should they use?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Istio or Anthos Service Mesh
Option B is correct because Istio or Anthos Service Mesh provides fine-grained traffic splitting capabilities for canary deployments in a GKE environment. It uses Envoy sidecar proxies to route a percentage of traffic to different service versions based on HTTP headers or weight, enabling controlled rollouts without modifying application code.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
ClusterIP service
Why it's wrong here
Internal only, does not support traffic splitting for external canary deployments.
✓
Istio or Anthos Service Mesh
Why this is correct
Provides advanced traffic management, including weight-based canary deployments.
Related concept
Read the scenario before looking for a memorised answer.
✓
Ingress resource
Why this is correct
Can route gRPC traffic to multiple backends with header-based routing for canary.
Related concept
Read the scenario before looking for a memorised answer.
✓
Google Cloud Load Balancer
Why this is correct
Global load balancer can distribute traffic across backend services for canary testing.
Related concept
Read the scenario before looking for a memorised answer.
✗
Headless service
Why it's wrong here
Used for stateful applications, not for traffic splitting.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse ClusterIP or Headless services with traffic splitting capabilities, but these are only for basic service discovery and do not provide the advanced routing needed for canary deployments.
Detailed technical explanation
How to think about this question
Under the hood, Istio uses VirtualService and DestinationRule CRDs to define traffic routing policies, such as weight-based splitting (e.g., 90% to v1, 10% to v2) or header-based matching. The Envoy sidecars intercept all gRPC traffic and apply these rules at the L7 layer, supporting gRPC's HTTP/2 multiplexing. In a real-world scenario, this allows gradual rollout of a new gRPC service version while monitoring error rates and latency before full promotion.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Designing highly scalable, available, and reliable cloud-native applications — This question tests Designing highly scalable, available, and reliable cloud-native applications — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Istio or Anthos Service Mesh — Option B is correct because Istio or Anthos Service Mesh provides fine-grained traffic splitting capabilities for canary deployments in a GKE environment. It uses Envoy sidecar proxies to route a percentage of traffic to different service versions based on HTTP headers or weight, enabling controlled rollouts without modifying application code.
What should I do if I get this PCD question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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