Configuring as an inverse mask

Unanswered Question
Jul 24th, 2007


Just want to check that I understand this correctly.

You can configure an inverse mask like this,, 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 would allow anything from through



I have this problem too.
0 votes
  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
Paolo Bevilacqua Tue, 07/24/2007 - 03:54


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!


This Discussion