- A
The Cloud Trace sampling rate is too low, causing statistical noise.
Why wrong: Sampling rate affects which requests are traced, not the actual latency of individual requests.
- B
The gRPC client is not using connection pooling, causing frequent TLS handshakes.
Correct: without connection pooling, each call may require a new handshake, adding latency especially during bursts.
- C
The backend service is under-provisioned and experiencing resource contention only during peak traffic.
Why wrong: Under-provisioning would typically cause increased latency across all requests, not just occasional spikes, and likely log errors.
- D
The network latency between the client and backend is high due to a misconfigured VPC firewall.
Why wrong: Firewall rules do not add latency; they either allow or block traffic.
Quick Answer
The answer is that the gRPC client is not using connection pooling, causing frequent TLS handshakes. This is correct because gRPC relies on HTTP/2, which multiplexes multiple requests over a single persistent connection; without connection pooling, each new request triggers a separate TLS handshake, adding 100-500ms of latency due to certificate exchange and cryptographic operations. On the Google Professional Cloud Developer exam, this scenario tests your understanding of gRPC connection management on GKE, where the common trap is to blame the backend service or network when logs show no errors—the real culprit is client-side channel reuse. Remember the memory tip: "One channel, many calls; no pool, slow stalls."
PCD Managing application performance monitoring Practice Question
This PCD practice question tests your understanding of managing application performance monitoring. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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.
An application deployed on Google Kubernetes Engine is experiencing intermittent latency spikes. The team has enabled Cloud Trace and sees that a specific gRPC call to a backend service occasionally takes >500ms. However, the backend service's logs show no errors. What is the most likely cause that the team should investigate further?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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
The gRPC client is not using connection pooling, causing frequent TLS handshakes.
Option B is correct because gRPC relies on HTTP/2, which multiplexes multiple requests over a single persistent connection. If the client does not reuse connections, each new request triggers a new TLS handshake, which can add significant latency (often 100-500ms) due to certificate exchange and cryptographic operations. This intermittent behavior occurs when the client creates a new channel per request rather than reusing a connection pool, leading to sporadic high-latency calls without backend errors.
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.
- ✗
The Cloud Trace sampling rate is too low, causing statistical noise.
Why it's wrong here
Sampling rate affects which requests are traced, not the actual latency of individual requests.
- ✓
The gRPC client is not using connection pooling, causing frequent TLS handshakes.
Why this is correct
Correct: without connection pooling, each call may require a new handshake, adding latency especially during bursts.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The backend service is under-provisioned and experiencing resource contention only during peak traffic.
Why it's wrong here
Under-provisioning would typically cause increased latency across all requests, not just occasional spikes, and likely log errors.
- ✗
The network latency between the client and backend is high due to a misconfigured VPC firewall.
Why it's wrong here
Firewall rules do not add latency; they either allow or block traffic.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between client-side and server-side issues in microservices; the trap here is assuming that latency spikes must originate from the backend (resource contention or network problems) rather than considering client-side connection management, especially with gRPC's HTTP/2 multiplexing behavior.
Detailed technical explanation
How to think about this question
gRPC uses HTTP/2 streams over a single TCP connection, and connection pooling is critical to avoid the overhead of TLS handshakes, which involve up to 2 round trips (TCP + TLS 1.3) and CPU-intensive asymmetric cryptography. In Kubernetes, gRPC clients often use a channel per request if not configured with a shared channel or connection pool, leading to repeated handshakes that can spike latency to 500ms+. The absence of backend errors confirms the issue is client-side, as the backend processes the request normally once the connection is established.
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 healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
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.
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FAQ
Questions learners often ask
What does this PCD question test?
Managing application performance monitoring — This question tests Managing application performance monitoring — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The gRPC client is not using connection pooling, causing frequent TLS handshakes. — Option B is correct because gRPC relies on HTTP/2, which multiplexes multiple requests over a single persistent connection. If the client does not reuse connections, each new request triggers a new TLS handshake, which can add significant latency (often 100-500ms) due to certificate exchange and cryptographic operations. This intermittent behavior occurs when the client creates a new channel per request rather than reusing a connection pool, leading to sporadic high-latency calls without backend errors.
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.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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Last reviewed: Jun 25, 2026
This PCD practice question is part of Courseiva's free Google Cloud certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PCD exam.
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