I've been administrating an office network that was set up by someone else and I always found this weird about it:
Their internal subnet is in this range: 172.253.16.0/24. It's been working fine, but it does not conform with RFC 1918.
I've been trying to find out who has IPs in the range 172.32.0.0/8, but a simple WHOIS only shows that they "belong" to ARIN. Could it be that they're simply unassigned? I tried ICMP pinging a wide range of them and got no response...
I guess I'll eventually change the subnet to something more standard, but it's a curious thing, don't you think?