IPV4 Network

IPv4 is the core addressing method that has powered the internet since the 1980s. Every computer, phone, or server using IPv4 gets a 32-bit number as its address, written as four octets like 10.0.0.1. Because it’s only 32 bits, the total pool is around 4.3 billion addresses. That pool officially ran out years ago, but the internet still works thanks to workarounds: ISPs give customers private IPs and use NAT to share public ones, companies reuse addresses internally, and older unused blocks got reclaimed. An IPv4 header is 20 bytes minimum and handles things like packet size, lifetime, and protocol type so routers know how to forward it. IPv6 with 128-bit addresses is the long-term replacement, but IPv4 refuses to die because it’s simple, every device understands it, and upgrading global infrastructure is slow. Most websites in 2026 still run “dual-stack” — they speak both IPv4 and IPv6.