NSE7 Advanced VPN and Zero Trust Practice Question
What is the purpose of Dead Peer Detection (DPD) in an IPsec VPN?
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
✓
Detect loss of connectivity to the remote VPN peer
DPD is used to detect if the remote peer is still alive. It sends periodic messages and if no response is received, the tunnel is considered down. Option A is correct.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Detect loss of connectivity to the remote VPN peer
Why this is correct
DPD monitors the liveness of the remote VPN peer. If the peer becomes unreachable, DPD detects it and the tunnel can be torn down.
- ✗
Detect if the VPN tunnel is using the correct encryption algorithm
Why it's wrong here
Encryption algorithm correctness is verified during negotiation, not via DPD.
- ✗
Detect duplicate IP addresses on the network
Why it's wrong here
Duplicate IP detection is done by ARP, not DPD.
- ✗
Detect packet loss over the VPN tunnel
Why it's wrong here
Packet loss detection is QoS or performance monitoring, not DPD.
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 NSE7 practice question is part of Courseiva's free Fortinet 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 NSE7 exam.