What is a callback system?

A.
It is a remote-access system whereby the remote-access server immediately calls the user
back at a predetermined number if the dial-in connection fails.

B.
It is a remote-access system whereby the user’s application automatically redials the
remoteaccess server if the initial connection attempt fails.

C.
It is a remote-access control whereby the user initially connects to the network systems via dialup access, only to have the initial connection terminated by the server, which then subsequently
dials the user back at a predetermined number stored in the server’s configuration database.

D.
It is a remote-access control whereby the user initially connects to the network systems via dialup access, only to have the initial connection terminated by the server, which then subsequently
allows the user to call back at an approved number for a limited period of time.

Explanation:
A callback system is a remote-access control whereby the user initially connects to
the network systems via dial-up access, only to have the initial connection terminated by the
server, which then subsequently dials the user back at a predetermined number stored in the
server’s configuration database.