1.1.1.1: Fast, privacy-first consumer DNS service

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

The most useful case for this shortcut is 127.1 -> 127.0.0.1

Don't try that in the wild, most sw out there would ignore spec and use some arbitrary regex to validate IP format.

i.e python:

    octets = ip_str.split('.')
    if len(octets) != 4:
        raise AddressValueError("Expected 4 octets in %r" % ip_str)

What spec says that 127.1 and 127.0.0.1 are equivalent?

I don’t actually think it’s in a spec formally but is in a common c lib[0].

> a.b

> Part a specifies the first byte of the binary address. Part b is interpreted as a 24-bit value that defines the rightmost three bytes of the binary address. This notation is suitable for specifying (outmoded) Class C network addresses.

[0]: https://linux.die.net/man/3/inet_aton