When configuring ISAKMP for IKEv1 Phase 1 on a Cisco IOS router, an administrator needs to input the command crypto isak

[answerhappygod]

When configuring ISAKMP for IKEv1 Phase 1 on a Cisco IOS router, an administrator needs to input the command crypto isakmp key cisco address 0.0.0.0.
The administrator is not sure what the IP address in this command is used for. What would be the effect of changing the IP address from 0.0.0.0 to 1.2.3.4?

A. The key server that is managing the keys for the connection will be at 1.2.3.4.
B. The address that will be used as the crypto validation authority.
C. All IP addresses other than 1.2.3.4 will be allowed.
D. The remote connection will only be allowed from 1.2.3.4.