Classful networks approach was deprecated in favour of CIDR quite a while ago.
However, we still have some parts of it in the kernel. If one wants to add an interface address/alias and adds it without a mask, instead of adding "host" address, kernel adds a mask based on classful addressing:
10:52  m@devel2 s ifconfig vtnet0 alias 10.11.0.2 10:52  m@devel2 s ifconfig vtnet0 vtnet0: flags=8863<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 options=4c07bb<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,TSO4,TSO6,LRO,VLAN_HWTSO,LINKSTATE,TXCSUM_IPV6> ether 52:54:00:14:e3:19 inet 10.0.0.8 netmask 0xffffff00 broadcast 10.0.0.255 inet 10.11.0.2 netmask 0xff000000 broadcast 10.255.255.255 ^^^^^^^^^^^
Retire this behaviour and assume /32 mask in such cases.