IPv4 (Internet Protocol version 4) is the foundational network layer protocol used for routing data packets across the internet and private networks. It employs a 32-bit addressing scheme, providing a theoretical maximum of approximately 4.3 billion unique IP addresses. It was the first version of the protocol to be widely deployed and remains the dominant standard for network communication.
An IPv4 address is represented in dot-decimal notation, consisting of four octets ranging from 0 to 255, such as 172.16.254.1. As a connectionless protocol, it treats each packet independently and does not guarantee delivery, order, or integrity; these functions are offloaded to transport layer protocols like TCP.
Technical Characteristics
- Header Structure: A standard IPv4 header is 20 bytes long and contains fields such as Source Address, Destination Address, and Protocol.
- TTL (Time to Live): A mechanism that prevents packets from circulating indefinitely by decrementing a counter at each router hop.
- Fragmentation: The process of breaking down packets into smaller units to fit the MTU of a specific network segment.
Due to the exhaustion of available addresses, IPv4 networks heavily rely on NAT (Network Address Translation) and Private IP ranges (RFC 1918) to allow multiple devices to share a single public IP address. While IPv6 is the intended successor, IPv4 continues to support the majority of global internet traffic through these optimization techniques.