Which of the following protocols operates at the session layer (layer 5)?

A.
RPC

B.
IGMP

C.
LDP

D.
SPX

Explanation:
The socket method of network use is a message-based system, in which one process writes a
message to another. This is a long way from the procedural model. The remote procedure call is
intended to act like a procedure call, but to act across the network transparently. The process makes
a remote procedure call by pushing its parameters and a return address onto the stack, and jumping
to the start of the procedure. The procedure itself is responsible for accessing and using the
network. After the remote execution is over, the procedure jumps back to the return address. The
calling process then continues. RPC works at the Session layer of the OSI model.