ANS-C01 Network Management and Operations Practice Question
A company has a transit gateway with multiple VPC attachments and an on-premises VPN connection. The network team is seeing asymmetric routing and packet drops. What should they implement to resolve this?
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
✓
Use BGP ASN prepending on the on-premises routers.
BGP ASN prepending on the on-premises routers can influence the path selection by making one path less preferred, thereby breaking the equal-cost multipath (ECMP) behavior that causes asymmetric routing. AWS Transit Gateway does not support disabling ECMP; it always uses ECMP for equal-cost paths. By prepending ASN, the on-premises side advertises routes with a longer AS path, making the VPN path less attractive and forcing all traffic through a single preferred path, resolving asymmetry. Option A is incorrect because AWS Transit Gateway does not allow ECMP to be disabled. Option B is incorrect because VPC peering does not address routing through a Transit Gateway. Option D is incorrect because route propagation simply advertises routes and does not affect ECMP behavior.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Disable equal-cost multipath (ECMP) routing on the Transit Gateway.
Why it's wrong here
Incorrect. AWS Transit Gateway does not allow disabling ECMP; ECMP is always enabled for equal-cost paths.
- ✗
Create VPC peering connections between all VPCs.
Why it's wrong here
Incorrect. VPC peering connections do not resolve asymmetric routing through a Transit Gateway; they provide direct connectivity between VPCs but do not influence path selection.
- ✓
Use BGP ASN prepending on the on-premises routers.
Why this is correct
Correct. BGP ASN prepending on the on-premises routers makes the VPN path appear less preferred due to a longer AS path, breaking ECMP and ensuring symmetric routing.
- ✗
Enable route propagation from the Transit Gateway to VPC route tables.
Why it's wrong here
Incorrect. Enabling route propagation simply adds routes to VPC route tables and does not affect ECMP behavior or path selection.
Visual reference
Quick reference
Asymmetric Encryption Algorithm Comparison
| Algorithm | Key Exchange | Signatures | Equivalent Security Key | Notes |
|---|---|---|---|---|
| RSA-3072 | Yes | Yes | 128-bit | Widely deployed; slow for bulk data |
| ECDSA P-256 | No | Yes | 128-bit | Fast signatures; standard TLS certs |
| ECDH / ECDHE | Yes | No | 128-bit | Perfect forward secrecy in TLS 1.3 |
| DH / DHE | Yes | No | 128-bit (3072-bit key) | Replaced by ECDHE in modern TLS |
| Ed25519 | No | Yes | ~128-bit | SSH keys, modern PKI |
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.