- A
The MTU size is set to 9001 (jumbo frames) on the Direct Connect interface.
Why wrong: Jumbo frames do not cause BGP flapping; they affect packet fragmentation.
- B
The link experiences occasional packet loss causing BGP hold timer expiration.
Packet loss can cause keepalive messages to be lost, leading to hold timer expiry and BGP session reset.
- C
The BGP authentication key is mismatched between the customer router and AWS.
Why wrong: Incorrect authentication would cause the session to never establish or drop immediately, not flap.
- D
The Multi-Exit Discriminator (MED) value is set too high on the customer router.
Why wrong: MED affects route preference, not session stability.
Question 784 of 1,705
Troubleshooting BGP Flapping on Direct Connect: Packet Loss and Hold Timer
This ANS-C01 practice question tests your understanding of network implementation. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 network engineer is troubleshooting high latency on a Direct Connect connection. The engineer notices that the BGP session is flapping intermittently. The connection is a 1 Gbps dedicated connection with a single private VIF. The router configuration uses default BGP timers. What is the most likely cause of the flapping?
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 link experiences occasional packet loss causing BGP hold timer expiration.
B is correct because the BGP hold timer (default 90 seconds) expires when the link experiences intermittent packet loss, causing the BGP session to flap. This is a common issue on Direct Connect when the underlying physical link has transient errors or congestion, leading to missed keepalive messages and session resets.
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 MTU size is set to 9001 (jumbo frames) on the Direct Connect interface.
Why it's wrong here
Jumbo frames do not cause BGP flapping; they affect packet fragmentation.
- ✓
The link experiences occasional packet loss causing BGP hold timer expiration.
Why this is correct
Packet loss can cause keepalive messages to be lost, leading to hold timer expiry and BGP session reset.
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 BGP authentication key is mismatched between the customer router and AWS.
Why it's wrong here
Incorrect authentication would cause the session to never establish or drop immediately, not flap.
- ✗
The Multi-Exit Discriminator (MED) value is set too high on the customer router.
Why it's wrong here
MED affects route preference, not session stability.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse BGP session flapping with configuration errors (like authentication or MED) rather than recognizing that transient packet loss is the most common cause of hold timer expiration on a single physical link.
Detailed technical explanation
How to think about this question
BGP uses keepalive messages (default 30-second interval) and a hold timer (default 90 seconds) to maintain session liveness. On a Direct Connect link, even 0.1% packet loss can cause keepalive drops, triggering hold timer expiration and session reset. This is often exacerbated by bursty traffic or suboptimal physical layer conditions like signal degradation or CRC errors.
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.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this ANS-C01 question test?
Network Implementation — This question tests Network Implementation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The link experiences occasional packet loss causing BGP hold timer expiration. — B is correct because the BGP hold timer (default 90 seconds) expires when the link experiences intermittent packet loss, causing the BGP session to flap. This is a common issue on Direct Connect when the underlying physical link has transient errors or congestion, leading to missed keepalive messages and session resets.
What should I do if I get this ANS-C01 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.
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Last reviewed: Jul 4, 2026
This ANS-C01 practice question is part of Courseiva's free Amazon Web Services 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 ANS-C01 exam.
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