Configuring 0.255.0.255 as an inverse mask

Andrew Morris · ‎07-24-2007

All,

Just want to check that I understand this correctly.

You can configure an inverse mask like this, 0.255.0.255, right?

My understanding is that the "255" represents all 1's so in that case is allowed.

So used in an access list for example:

permit 10.0.3.0 0.255.0.255 would allow anything from 10.0.3.0 through 10.254.0.254?

Regards

Andrew

paolo bevilacqua · ‎07-24-2007

Hi,

What you have done is a discontiguous mask. Their use is never recommended because these are counter-intuitive and everything done with them can be done with contiguous masks that are easier to read and understand.

Hope this helps, please rate post if it does!