Greetings,
A colleague of mine has static routed 172.16.0.0/32 to a usable IP address, to have a single known IP address be static routed to a regions closest server. While I understand the IP address does work (pings and what not), I don't feel this should be the proper IP address used, but something more feasible like a usable IP in a dedicated range (172.31.0.0/24 for example).
I would to hear everyone's thoughts on this, as this the first IP address in an RFC1918 range.
Thanks,
I think I'd rate this one as "gross but technically not breaking any rules
I suppose." (I couldn't find any at first glance, anyway.)
+1 for gross comment.
Nothing wrong with using xxx.0 or xxx::0 in the context of a host route
(/32 or /128).
Greetings,
A colleague of mine has static routed 172.16.0.0/32 to a usable IP address,
to have a single known IP address be static routed to a regions closest server.
While I understand the IP address does work (pings and what not), I don't feel
this should be the proper IP address used, but something more feasible like a
usable IP in a dedicated range (172.31.0.0/24 for example).
Probably depends on what your colleague is trying to do. Nothing in the
rules says the .0 address on a subnet is reserved (though you're in for a
surprise if there's any gear still on the net with a 4.2BSD stack).
I would to hear everyone's thoughts on this, as this the first IP address in
an RFC1918 range.
At some point, some chucklehead is going to look at that .0.0 and mentally think /16,
and things will go pear-shaped pretty quickly....
note that in times past (perhaps even now marked historical) there were
platforms which got unhappy with network/broadcast addresses being used as
host addresses...
At least some windows platforms balked at .0 or .255 host addresses (even
if that address was 'off-net' from them).
maybe this is all history though 
Nothing wrong with using xxx.0 or xxx::0 in the context of a host route
(/32 or /128).
note that in times past (perhaps even now marked historical) there were
platforms which got unhappy with network/broadcast addresses being used as
host addresses...At least some windows platforms balked at .0 or .255 host addresses (even
if that address was 'off-net' from them).maybe this is all history though
It is 2017... if you encounter such platforms you take them out back and
“set them free”. 
We can, and must, expect CIDR compliance these days.
Kind regards,
Job
Hi Ryan,
Some clarifications:
1. You say, "static routed to a regions closest server." What do you mean
by that? A static-routed anycast address?
2. In what reachability context? Is this a private network? An ISP network
where the reachability should be the ISP and its customers?
Regards,
Bill Herrin
Last time I tried using the first address of a classful address block (which 172.16.0.0/32 would be) in Cisco IOS (classic), that didn't work properly. This was in IOS 12.0.x. You can't set up BGP peers to something in the network address in classful network space, for instance. So 172.16.0.0/32 or 172.16.255.255/32 wouldn't work (because it's first and last address of class B space), but 172.16.1.0 worked just fine (because in class B space, 172.16.1.0 isn't special).
So while this has been allowed per standardssince mid 90:ties, it's not obvious that it'll work in all operating systems that might still be in use.
For a host route, no problem. For the host itself - a slightly different
story.