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.