ANS-C01 Network Management and Operations Practice Question
A network engineer is configuring an AWS Site-to-Site VPN with dynamic routing (BGP). The customer gateway device is a Cisco router. The VPN tunnel is established, but BGP is not forming. Which configuration on the Cisco router is most likely missing?
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 BGP neighbor statement with the correct Amazon ASN (64512).
The VPN tunnel is established, indicating IKE phase 1 and IPsec are functioning, so options A, B, and C are not the issue. For BGP to form, the Cisco router must have a BGP neighbor statement pointing to the correct Amazon ASN (64512) and the tunnel interface IP. Without this, BGP will not establish a session. Options A, B, and C are incorrect because the tunnel is up, so local IP, tunnel interface IP, and pre-shared key are properly configured.
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 VPN connection's local IP address.
Why it's wrong here
Local IP is used for tunnel establishment, not BGP.
- ✗
The correct IP address for the tunnel interface.
Why it's wrong here
Tunnel is up, so IP is configured.
- ✗
The pre-shared key for IKE phase 1.
Why it's wrong here
Tunnel is established, so IKE works.
- ✓
The BGP neighbor statement with the correct Amazon ASN (64512).
Why this is correct
ASN mismatch is a common cause of BGP not forming.
Quick reference
VPN Protocol Comparison
| Protocol | Port | Encryption | Authentication | Use Case |
|---|---|---|---|---|
| IKEv2 / IPsec | UDP 500 / 4500 | AES-256 | Certificates / PSK | Site-to-site & remote access |
| SSL / TLS VPN | TCP 443 | TLS 1.3 | Certificates / MFA | Clientless remote access |
| L2TP / IPsec | UDP 1701 | AES (IPsec) | PSK / Certificates | Legacy remote access |
| WireGuard | UDP 51820 | ChaCha20 | Public keys | Modern high-performance VPN |
| PPTP | TCP 1723 | MPPE (weak) | MS-CHAPv2 | Legacy — avoid in production |
PPTP is considered insecure. IKEv2/IPsec and SSL VPN are the current recommended options.
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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.