Which two statements about the functionality of a gatekeeper are true? (Choose two.)

A.
Cisco Unified Communications Manager has gatekeeper functionality built in.

B.
Cisco Unified Communications Manager registers with a gatekeeper via SIP.

C.
Cisco Unified Communications Manager registers with a gatekeeper via H.323.

D.
A gatekeeper can enable CAC and AAR.

E.
A gatekeeper can enable CAC, but not AAR.