LDF is a protocol specially formulated for label distribution. There are many types of messages. Among them, the messages used to announce and maintain the existence of an LSR in the network are:

LDF is a protocol specially formulated for label distribution. There are many types of messages. Among them, the messages used to announce and maintain the existence of an LSR in the network are:
A . Discovery message
B . Session message
C . Advertisement message
D . notifcation message

Answer: A