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 fail
B. It is a remote-access system whereby the user's application automatically redials the remoteaccess server if the initial connection attempt fail
C. It 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 databas
D. It 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 allows the user to call back at an approved number for a limited period of tim