Which four statements about an IP service level agreement (SLA) are true? (Choose four)

A.
SLA responder knows type of operation, the port used, and duration.

B.
SLA responder inserts in and out timestamps in the packet payload.

C.
SLA sender and responder use the IP SLA Control Protocol to communicate with each other
before sending test packets.

D.
SLA sender and responder communication can be encrypted.

E.
SLA sender and responder communication can be authenticated with MD5.