[Resending - since I don't think my mail client actually sent this the first time] While reviewing https://review.openstack.org/#/c/204459/ - I noticed that one of the unit tests is passing an IP address "1/32" - so I went and looked up the constructor for netaddr.IPNetwork, which has a feature that expands a string into a prefix. http://pythonhosted.org//netaddr/api.html?highlight=abbreviated%20cidr#ip-networks-and-subnets Putting it into my REPL: http://paste.openstack.org/show/421041/ So - is this an actual IP address? I could be horribly wrong, but it doesn't look like one to me - especially since built in tools like ping don't appear to like it. scollins at Sean-Collins-MBPr15 ~ » ping 1/32 ping: cannot resolve 1/32: Unknown host Although, ping has it's own interesting behavior. scollins at Sean-Collins-MBPr15 ~ » ping 1 68 ↵ PING 1 (0.0.0.1): 56 data bytes ping: sendto: No route to host ping: sendto: No route to host Request timeout for icmp_seq 0 ^C --- 1 ping statistics --- 2 packets transmitted, 0 packets received, 100.0% packet loss scollins at Sean-Collins-MBPr15 ~ » ping 60 2 ↵ PING 60 (0.0.0.60): 56 data bytes ping: sendto: No route to host ping: sendto: No route to host Request timeout for icmp_seq 0 ^C --- 60 ping statistics --- 2 packets transmitted, 0 packets received, 100.0% packet loss Oh, also spelunking through the code of Netaddr, it looks like this option is going to be deprecated? https://github.com/drkjam/netaddr/blob/bfba0b80c2e88b6e00ca7a870998b630d7c29734/netaddr/ip/__init__.py#L776 Which calls into: https://github.com/drkjam/netaddr/blob/bfba0b80c2e88b6e00ca7a870998b630d7c29734/netaddr/ip/__init__.py#L1438 So - the tl;dr is that I don't think that we should accept inputs like the following: x -> 192 x/y -> 10/8 x.x/y -> 192.168/16 x.x.x/y -> 192.168.0/24 which are equivalent to:: x.0.0.0/y -> 192.0.0.0/24 x.0.0.0/y -> 10.0.0.0/8 x.x.0.0/y -> 192.168.0.0/16 x.x.x.0/y -> 192.168.0.0/24 -- Sean M. Collins