PING 127.12.34.56 (127.12.34.56): 56 data bytes
Request timeout for icmp_seq 0
There's also ip unnumbered where an interface can reuse ip from one interface (typically from loopback) on other interfaces.
There's also ip unnumbered where an interface can reuse ip from one interface (typically from loopback) on other interfaces.
127.0.0.0/8 - This block is assigned for use as the Internet host
loopback address. A datagram sent by a higher-level protocol to an
address anywhere within this block loops back inside the host. This
is ordinarily implemented using only 127.0.0.1/32 for loopback.
An ICMP Ping is a datagram in the sense of the second sentence.
Also:
This is ordinarily implemented using only 127.0.0.1/32 for loopback.
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
options=1203<RXCSUM,TXCSUM,TXSTATUS,SW_TIMESTAMP>
inet 127.0.0.1 netmask 0xff000000
inet6 ::1 prefixlen 128
inet6 fe80::1%lo0 prefixlen 64 scopeid 0x1
nd6 options=201<PERFORMNUD,DAD>