Why do you think the network portion needs to be contiguous?

Well, it does now. But that was not always the case.

https://www.quora.com/Why-is-the-subnet-mask-255-255-255-64-invalid/answer/Patrick-W-Gilmore
https://www.quora.com/Why-is-the-subnet-mask-255-255-255-64-invalid

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TTFN,
patrick

On Dec 19, 2018, at 09:54, Naslund, Steve <SNaslund@medline.com> wrote:

I am wondering how a netmask could be not contiguous when the network portion of the address must be contiguous.  I suppose a bit mask could certainly be anything you want but a netmask specifically identifies the network portion of an address.

Steve

I seem to remember that before the advent of VLSM and CIDR there was
no requirement for the 1 bits in the netmask to be contiguous with no
intervening 0 bits and there was always someone who tested it out on a
production network just to prove a point (usually only once)