25/08/2026
**IPsec / IKEv1 Interview Questions — Main Mode**
**Q1. When is the SA (Security Association) proposal negotiated in IKEv1 Main Mode?**
The SA proposal is negotiated during the 1st and 2nd message exchanges (MM1/MM2).
**Q2. During which message exchange does the Diffie-Hellman key exchange occur?**
The DH key exchange occurs during the 3rd and 4th message exchanges (MM3/MM4).
**Q3. From which message exchange does encryption start in IKEv1 Main Mode?**
Encryption begins from the 5th message exchange onward (MM5/MM6), once identity and authentication payloads are exchanged.
