Internet Addresses
Values specified using the ".'' notation take one of the following forms:
a.b.c.d
a.b.c
a.b
a
When four parts are specified, each is interpreted as a byte of data and assigned, from left to right, to the four bytes of an Internet address. When an Internet address is viewed as a 32-bit integer quantity on the Intel architecture, the bytes referred to above appear as "d.c.b.a''. That is, the bytes on an Intel processor are ordered from right to left.
The parts that make up an address in "." notation can be decimal, octal or hexidecimal as specified in the C language. Numbers that start with "0x" or "0X" imply hexidecimal. Numbers that start with "0" imply octal. All other numbers are interpreted at decimal.
"4.3.2.16" decimal
"004.003.002.020" octal
"0x4.0x3.0x2.0x10" hexidecimal
"4.003.002.0x10" mix
Note The following notations are only used by Berkeley, and nowhere else on the Internet. In the interests of compatibility with their software, they are supported as specified.
When a three part address is specified, the last part is interpreted as a 16-bit quantity and placed in the right most two bytes of the network address. This makes the three part address format convenient for specifying Class B network addresses as "128.net.host''.
When a two part address is specified, the last part is interpreted as a 24-bit quantity and placed in the right most three bytes of the network address. This makes the two part address format convenient for specifying Class A network addresses as "net.host''.
When only one part is given, the value is stored directly in the network address without any byte rearrangement.
For more information, see MSDN Online.