ip subnet zero

JSW77

im a little foggy on cidr, ip classless, ip subnet zero etc...Does ip subnet zero enable both the zero subnet and the broadcast subnet or just the zero? If it is specified that ip subnet zero is enabled, do you figure subnets as 2^n, or 2^n-1? is cidr expected knowledge for the ccna or is this more of a ccnp subject? thanks.

mason1973

If it's CIDR use 2^n otherwise you use 2^n-2

Most routers use the CIDR system but Cisco likes to go over both for the tests.