Analysis of information sources in references of the Wikipedia article "IP address" in English language version.
An IPv4 address has the following format: x . x . x . x where x is called an octet and must be a decimal value between 0 and 255. Octets are separated by periods. An IPv4 address must contain three periods and four octets. The following examples are valid IPv4 addresses:
1 . 2 . 3 . 4
01 . 102 . 103 . 104