TIL you can also use 1.1 and it will expand to 1.0.0.1
$> ping 1.1
PING 1.1 (1.0.0.1) 56(84) bytes of data.
64 bytes from 1.0.0.1: icmp_seq=1 ttl=55 time=28.3 ms
64 bytes from 1.0.0.1: icmp_seq=2 ttl=55 time=33.0 ms
64 bytes from 1.0.0.1: icmp_seq=3 ttl=55 time=43.6 ms
64 bytes from 1.0.0.1: icmp_seq=4 ttl=55 time=41.7 ms
64 bytes from 1.0.0.1: icmp_seq=5 ttl=55 time=56.5 ms
64 bytes from 1.0.0.1: icmp_seq=6 ttl=55 time=38.4 ms
64 bytes from 1.0.0.1: icmp_seq=7 ttl=55 time=34.8 ms
64 bytes from 1.0.0.1: icmp_seq=8 ttl=55 time=45.7 ms
64 bytes from 1.0.0.1: icmp_seq=9 ttl=55 time=45.2 ms
64 bytes from 1.0.0.1: icmp_seq=10 ttl=55 time=43.1 ms
replies(5):