Dictionary.net

Berkeley Unix notation for an Internetaddress, consisting of one to four numbers (a "dotted quad")in hexadecimal (leading 0x), octal (leading 0), or(usually) decimal. It represents a 32-bit address. Eachleading number represents eight bits of the address (high bytefirst) and the last number represents the rest. E.g. address0x25.32.0xab represents 0x252000ab. By far the most commonform is four decimal numbers, e.g. 146.169.22.42.Many programs accept an address in dot notation in place of ahostname.