Subnet/Wilcard Masks

[Sik]

I am currently preparing for my ICND2 exam and do not really understand why we use both Subnet and Wildcard masks?

I know an access list must have a wildcard mask rather than a subnet mask but in theory is 255.255.255.128 not the same as 0.0.0.127 ?

 

[Tinuva]

It is exactly the same, access lists just require the use of wildcards instead of subnets, and network statements under bgp/ospfv2 config and interfaces need subnets.

So yes they the same, you still need to be able to understand both. At least its very easy so no worries there

 

[Sinbad]

A wildcard mask is exactly that - it defines the bits in the address that are variables in the filter.
A subnet mask defines the subnet bits in an address.

0.0.0.127 is a wildcard mask that matches all addresses in a 255.255.255.128 subnet.

 

[Sik]

they are simple enough, just curious as to why they are both used. Thanks for the replies.

writing the ICND2 in two days, just brushing up now.