Stupid Question maybe?

Wed Dec 19 20:50:35 UTC 2018

On Wed, 19 Dec 2018 21:11:39 +0100, Thomas Bellman said:
> On 2018-12-19 20:47 MET, valdis.kletnieks at vt.edu wrote:
> > There was indeed a fairly long stretch of time (until the CIDR RFC came out and
> > specifically said it wasn't at all canon) where we didn't have an RFC that
> > specifically said that netmask bits had to be contiguous.
>
> How did routers select the best (most specific) route for an address?
> If the routing table held both (e.g.) 10.20.30.0/255.255.255.64 and
> 10.20.30.0/255.255.255.32, then 10.20.30.97 would match both, and have
> the same number of matching bits.

That didn't stop sites getting creative with it on their internal networks, and I
wouldn't be surprised if at least one router (Bay, Proteon, whatever) happened
to have an implementation that Just Worked.

Remember - there were enough ambiguities and odd implementations that
RFC 1122/1123 had to be issued.  *Lots* of "How the <expletive> did that ever
work?" back in those days - and often the answer was "By accident".