Internet Protocol version 4 or IPv4 is the fourth version of the Internet Protocol (IP). IP is one of the core protocols for standards-based internetworking that is used on the Internet and other packet-switched networks.

IPv4 uses a 32-bit address space that provides 4,294,967,296 unique addresses. Addresses are expressed in dot decimal notation which consists of four octets of the address expressed individually in decimal numbers and separated by periods. The following are some examples of IPv4 address expressed in dot decimal notation, and their binary representations:

Dot decimalbinary

IPv4 uses the concept of a subnet mask to separate an address into the network portion and the host portion, giving IPv4 its hierarchical structure.

IPv4 resides on Layer 3 of the OSI model and is responsible for establishing unreliable end to end communication between hosts.

IPv4 was defined as a standard in 1981 and is still in widespread use today. IPv6 is the next version of the IP protocol which resolves many of the limitations that, over the years, the use of IPv4 has run into.




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