The answer is to check the BGP keepalive and hold timers on both sides. This is correct because BGP session flapping over AWS Direct Connect often stems from a mismatch in these timers, causing the session to reset when one side expects a keepalive before the other sends it, or from unstable routing updates that trigger repeated state transitions. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this scenario tests your ability to differentiate between a healthy physical link (Direct Connect virtual interface status 'up') and a misconfigured Layer 3 protocol; a common trap is to assume the issue is physical or to jump to resetting the connection. Remember the mnemonic "Keep Timers Tight" — always verify timer consistency and BGP logs before escalating to infrastructure changes.
ANS-C01 Network Management and Operations Practice Question
This ANS-C01 practice question tests your understanding of network management and operations. 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 company is experiencing intermittent connectivity issues between a VPC and an on-premises data center over an AWS Direct Connect connection. The network engineer checks the Direct Connect virtual interface status and sees it is 'up'. However, BGP sessions are flapping. Which action should the engineer take to diagnose the issue?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Check the BGP keepalive and hold timers on both sides.
Option B is correct because checking BGP session logs and timers helps identify flapping due to misconfigured timers or routing updates. Option A is wrong because it does not address BGP-specific issues. Option C is wrong because it involves changing routing, not diagnosing. Option D is wrong because it is an extreme measure that may not resolve the BGP issue.
Key principle: A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Verify the VLAN configuration on the customer router.
Why it's wrong here
VLAN mismatch would keep the interface down, not cause BGP flapping.
✗
Enable BFD on the Direct Connect virtual interface.
Why it's wrong here
BFD would detect failures faster but not diagnose existing flapping.
✗
Recreate the virtual interface with a new VLAN ID.
Why it's wrong here
Recreating is disruptive and may not resolve BGP timer issues.
✓
Check the BGP keepalive and hold timers on both sides.
Why this is correct
Inconsistent BGP timers can cause session flapping.
Related concept
Access ports place end devices into a single VLAN.
Common exam traps
Common exam trap: an active trunk can still block the VLAN you need
A trunk being up does not prove every VLAN is crossing it. Check allowed VLAN lists, native VLAN mismatch, VLAN existence and access-port assignment.
Detailed technical explanation
How to think about this question
VLAN questions usually combine access-port and trunking clues. The key is to identify whether the issue is local to one switchport, caused by the trunk, or caused by the VLAN not existing where it needs to exist.
KKey Concepts to Remember
Access ports place end devices into a single VLAN.
Trunk ports carry multiple VLANs between switches.
Allowed VLAN lists decide which VLANs can cross a trunk.
Native VLAN mismatch can create confusing symptoms.
TExam Day Tips
→Use show vlan brief to verify access VLANs.
→Use show interfaces trunk to verify trunk state and allowed VLANs.
→Do not treat every same-VLAN issue as a routing problem.
Key takeaway
A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.
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.
Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related ANS-C01 questions on switching, trunking, and access-port configuration.
Network Management and Operations — This question tests Network Management and Operations — Access ports place end devices into a single VLAN..
What is the correct answer to this question?
The correct answer is: Check the BGP keepalive and hold timers on both sides. — Option B is correct because checking BGP session logs and timers helps identify flapping due to misconfigured timers or routing updates. Option A is wrong because it does not address BGP-specific issues. Option C is wrong because it involves changing routing, not diagnosing. Option D is wrong because it is an extreme measure that may not resolve the BGP issue.
What should I do if I get this ANS-C01 question wrong?
Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related ANS-C01 questions on switching, trunking, and access-port configuration.
What is the key concept behind this question?
Access ports place end devices into a single VLAN.
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 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.
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.