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

A.
3 messages

B.
4 messages

C.
5 messages

D.
2 messages

E.
6 messages

Explanation:
The Aggressive Mode is an exchange in the first phase of IKE/ISAKMP (The ISAKMP Aggressive
Exchange) is like the Main Mode, but some messages are embedded to the others. The first
message proposes the policy, and passes data for key-exchange, the nonce and some
information for identification. The second message is a response which authenticates the
responder and concludes the policy and key-exchange. At this point all the information for
encryption key for the ISAKMP SA is exchanged and last the message could be encrypted, but
doesn’t have to be. The last message is used for authenticating the initiator and provides a proof
of participation in the exchange. The identity of the responder could not be protected, but by

encrypting the last message the identity of the initiator is protected.