Understanding IPsec SA (Security Association) Establishment

???? IPsec (IP Security) provides encrypted communication over IP networks.

???? Security Associations (SAs) define encryption, authentication, and key parameters for IPsec tunnels.

Two IPsec SA Modes:

1️⃣ Manual Mode:

All parameters (keys, encryption methods, authentication settings) must be manually configured.

Keys do not change automatically, making it less secure.

2️⃣ IKE (Internet Key Exchange) Auto-Negotiation Mode:

Uses IKE Phase 1 and Phase 2 to automatically negotiate, generate, and exchange keys.

Keys are periodically refreshed, increasing security.

Uses Diffie-Hellman (DH) key exchange for secure key generation.

Why is Answer D Incorrect?

❌ D. SAs established in both manual and IKE auto-negotiation modes can be dynamically updated.

Incorrect: In manual mode, the IPsec SA is static and does not support dynamic updates.

Correct behavior: Only IKE auto-negotiation mode supports dynamic re-keying and SA updates.

✅ Reference: Huawei HCIE-Datacom Guide – IPsec SA Modes and IKE Negotiation