Google PCA Manage and provision cloud infrastructure Practice Question
This PCA practice question tests your understanding of manage and provision cloud infrastructure. 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 Cloud Router BGP session is flapping. The logs show 'Interface flapping due to changes in the underlying network'. What is the most likely cause?
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 the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
MTU mismatch across the network path.
The log message 'Interface flapping due to changes in the underlying network' indicates that the BGP session is unstable because the physical or logical interface is going up and down. An MTU mismatch across the network path can cause packet fragmentation issues, leading to intermittent connectivity and interface flaps as the router detects and recovers from the problem. This is the most likely cause because it directly affects the stability of the underlying network path.
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.
✓
MTU mismatch across the network path.
Why this is correct
MTU mismatch can cause intermittent packet loss, leading to BGP session flapping.
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.
✗
BGP MD5 authentication failure.
Why it's wrong here
Authentication failure would show a clear error message, not flapping.
✗
Incorrect local AS number in Cloud Router configuration.
Why it's wrong here
AS number mismatch would prevent the session from establishing at all.
✗
BGP timer misconfiguration between peers.
Why it's wrong here
Timer misconfiguration might cause session timeout but not flapping due to network changes.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often associate BGP flapping with timer misconfigurations or authentication issues, but the specific log message about 'changes in the underlying network' points directly to a Layer 2 or path-level problem like MTU mismatch, not BGP protocol errors.
Trap categories for this question
Command / output trap
Authentication failure would show a clear error message, not flapping.
Detailed technical explanation
How to think about this question
MTU mismatch occurs when a router or switch along the path has a lower Maximum Transmission Unit than the BGP packets being sent, causing fragmentation or drops. In Google Cloud, the default MTU is 1460 bytes for VPC networks, but if an on-premises peer uses a different MTU (e.g., 1500), packets may be silently dropped, leading to interface flaps as the Cloud Router retransmits and the link state toggles. This is often resolved by setting the Cloud Router's MTU to match the peer or enabling path MTU discovery (PMTUD) with ICMP messages.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this PCA question in full detail.
Manage and provision cloud infrastructure — This question tests Manage and provision cloud infrastructure — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: MTU mismatch across the network path. — The log message 'Interface flapping due to changes in the underlying network' indicates that the BGP session is unstable because the physical or logical interface is going up and down. An MTU mismatch across the network path can cause packet fragmentation issues, leading to intermittent connectivity and interface flaps as the router detects and recovers from the problem. This is the most likely cause because it directly affects the stability of the underlying network path.
What should I do if I get this PCA 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
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This PCA 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 PCA exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.