Subnet mask-A 32-bit combination used to describe which portion of an address refers to the subnet/network and which part refers to the host.
It is used alongwith IP Address.
Wildcard Mask- To indicate to the IOS software whether to check or ignore corresponding IP address bits when comparing the address bits in an access list entry , OSPF/EIGRP network command..
A wildcard mask is sometimes referred to as an inverted mask because a 1 and 0 mean the opposite of what they mean in a subnet (network) mask
e.g.
/30 : 255.255.255.252 subnet mask
0 . 0 . 0 . 3 wildcard mask
/24 : 255.255.255.0 subnet mask
0 . 0 . 0 . 255 wildcard mask
HTH..rate if useful..
