Subnetting - can I use the zero (first) and all-ones (last) subnet?

[friesen.s4]

Hello!

According to RFC 950 (Link) I can not use the zero and all-ones subnet by subnetting.

Is it still in force or I can use now the first (zero) and last (all-ones) subnet ?

Thank You!

[friesen.s4]

Update:

I mean the following example:

image source

[Richard Burts · Accepted solution]

The default behavior of Cisco routers and switches is to allow use of the zero and all ones subnets and has been that way for a long time. You can use all the subnets now.

HTH

Rick

[friesen.s4]

Thank You!