Netmask and Wildcard Masks

[michoudi]

I understand Netmask and Wildcard masks. What I'm trying to understand is why were wildcard masks created? I didn't put too much thought into it, but wouldn't regular netmasks work anywhere wildcard masks are needed?

If anyone could explain this to me I'd be greatly appreciative.

[maer]

With WC you may pick out non contiguos IP addreses like every second, every forth, all even, all odd etc. You can not do that with subnetmask since they have to have all ones to the left an all the zeroes to the right.