>Why do you think the network portion needs to be contiguous? Just because some equipment at one time let you configure a non-contiguous mask does not make it correct configuration. Please come up with any valid use case for a non-contiguous network (note NETWORK, not any other purpose) mask.
>Well, it does now. But that was not always the case. It has ALWAYS been the only correct way to configure equipment and is a requirement under CIDR. Here were your commonly used netmasks before CIDR/VLSM : 255.0.0.0 255.255.0.0 255.255.255.0 Which one is not contiguous? >https://www.quora.com/Why-is-the-subnet-mask-255-255-255-64-invalid/answer/Patrick-W-Gilmore In this example, the writer used it as a parlor trick to actually break a network. That's why you don't do it and it was never a good configuration. It just exploited a UI that did not validate the netmask. >https://www.quora.com/Why-is-the-subnet-mask-255-255-255-64-invalid In the second cited link, they are talking about using a non-contiguous mask in an access control function. That is perfectly valid to do, it just is not a NETmask anymore. By definition a netmask identifies the network portion of an address. In the cited example they are defining a group of subnets to an ACL. Steven Naslund Chicago IL > >-- >TTFN, >patrick
