man 3 inet_aton:
a.b.c.d Each of the four numeric parts specifies a byte of the
address; the bytes are assigned in left-to-right order to
produce the binary address.
a.b.c Parts a and b specify the first two bytes of the binary
address. Part c is interpreted as a 16-bit value that
defines the rightmost two bytes of the binary address.
This notation is suitable for specifying (outmoded) Class B
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
a The value a is interpreted as a 32-bit value that is stored
directly into the binary address without any byte
In all of the above forms, components of the dotted address can be
specified in decimal, octal (with a leading 0), or hexadecimal, with
a leading 0X). Addresses in any of these forms are collectively
termed IPV4 numbers-and-dots notation. The form that uses exactly
four decimal numbers is referred to as IPv4 dotted-decimal notation
(or sometimes: IPv4 dotted-quad notation).
For fun, try this:
$ nslookup unix.stackexchange.com
$ echo $(( (198 << 24) | (252 << 16) | (206 << 8) | 140 ))
$ ping 3338456716 # What? What did we ping just now?
PING stackoverflow.com (126.96.36.199): 48 data bytes
64 bytes from 188.8.131.52: icmp_seq=0 ttl=52 time=75.320 ms
64 bytes from 184.108.40.206: icmp_seq=1 ttl=52 time=76.966 ms
64 bytes from 220.127.116.11: icmp_seq=2 ttl=52 time=75.474 ms