When configuring a cisco router or switch, you may have been told that you can stop your console or telnet sessions from timing out by using the following configuration:
line con 0 !(or line vty 0 4) no exec-timeout !DON'T DO THIS!
NEVER issue the command “no exec-timeout” – instead it is much safer to use “exec-timeout 0”, because people make mistakes when typing “no exec-timeout” and end up with “no exec”, which means “do not run the Cisco IOS exec under this setting”. It can be used as a way of totally disabling the AUX port, (under line aux 0) or even disabling telnet (under line vty 0 4)
line con 0 !(or line vty 0 4) exec-timeout 0 !Much safer