How many messages does Internet Key Exchange (IKE) use to negotiate SA characteristics when
running in main mode?

A.
3 messages

B.
6 messages

C.
4 messages

D.
2 messages

E.
5 messages

Explanation:
3.1.1 Main Mode
The Main Mode is an exchange in the first phase of IKE/ISAKMP (The ISAKMP Identity Protection
Exchange) the first two messages are used for negotiating the security policy for the exchange.
The next two messages are used for the Diffie-Hellman keying material exchange. The last two
messages are used for authenticating the peers with signatures or hashes and optional
certificates. Last two authentication messages are encrypted with the previously negotiated key
and the identities of the parties are protected from eavesdroppers.