PCNE Practice Question: Designing, Planning, and Prototyping a GCP Network
A network engineer is configuring HA VPN between an on-premises network and GCP. They have created two external VPN gateways in GCP (one per region) and two Cloud Routers. How many IKEv2 tunnels and BGP sessions are required to achieve the 99.99% SLA?
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
✓
Four tunnels, four BGP sessions
HA VPN requires four tunnels (two per gateway) and four BGP sessions (one per tunnel) to achieve 99.99% SLA.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Four tunnels, four BGP sessions
Why this is correct
Four tunnels (two per gateway) with four BGP sessions meet the 99.99% SLA.
- ✗
Two tunnels, two BGP sessions
Why it's wrong here
Two tunnels provide 99.9% SLA, not 99.99%.
- ✗
Four tunnels, two BGP sessions
Why it's wrong here
Each tunnel needs its own BGP session for redundancy.
- ✗
Two tunnels, four BGP sessions
Why it's wrong here
HAs require four tunnels total.
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 PCNE 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 PCNE exam.