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350-401 Practice Question: Which two statements about IPsec IKEv2 are true?…
Which two statements about IPsec IKEv2 are true? (Choose two.)
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
✓
IKEv2 uses UDP port 500 for initial negotiation and can switch to UDP port 4500 for NAT traversal.
IKEv2 improves upon IKEv1 by using fewer messages for SA establishment and providing built-in NAT traversal and mobility support.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
IKEv2 uses UDP port 500 for initial negotiation and can switch to UDP port 4500 for NAT traversal.
Why this is correct
Correct because IKEv2 uses UDP 500 for standard exchanges and moves to UDP 4500 when NAT is detected, as per RFC 7296.
- ✗
IKEv2 requires a separate authentication phase for each security association established.
Why it's wrong here
Incorrect because IKEv2 uses a single IKE_SA for multiple CHILD_SAs, avoiding per-SA reauthentication.
- ✓
IKEv2 supports EAP authentication for remote access VPNs.
Why this is correct
Correct because IKEv2 natively supports EAP, enabling flexible authentication methods for remote users.
- ✗
IKEv2 uses only pre-shared keys for authentication and does not support digital certificates.
Why it's wrong here
Incorrect because IKEv2 supports both pre-shared keys and digital certificates (RSA, ECDSA) for authentication.
- ✗
IKEv2 is backward compatible with IKEv1 and can interoperate with older peers.
Why it's wrong here
Incorrect because IKEv2 is not backward compatible with IKEv1; they use different message formats and exchange procedures.
Visual reference
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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Same concept, more angles
1 more way this is tested on 350-401
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Which two statements about IPsec IKEv2 are true? (Choose two.)
medium- ✓ A.IKEv2 uses UDP port 500 for initial negotiation and can switch to UDP 4500 for NAT traversal.
- ✓ B.IKEv2 supports EAP authentication for remote access VPNs.
- C.IKEv2 uses TCP port 500 for control plane messages.
- D.IKEv2 requires a separate IPsec SA for each direction of traffic.
- E.IKEv2 is not compatible with certificate-based authentication.
Why A: IKEv2 uses UDP port 500 and 4500, supports EAP authentication, and is more robust than IKEv1. It does not use TCP, and it supports multiple simultaneous SAs.
Last reviewed: Jun 18, 2026
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