IP Address

An IP address is a numeric identifier assigned to a device on an IP network so that packets can be routed to and from it across the internet or a local network. Two versions exist: IPv4 (32-bit, written in dotted-decimal form such as 192.0.2.1) and IPv6 (128-bit, written in hexadecimal form such as 2001:db8::1). IPv6 was introduced because the original IPv4 address space is too small for the modern internet.

An IP address serves two roles at once: it identifies a particular network interface and it is used as the destination field during routing between routers. A domain name is only a human-readable label that DNS resolves to an IP address, while a MAC address identifies hardware on the same local segment — the IP address is what actually drives routing across networks.

IP addresses are split into public and private ranges. An public IP is globally routable on the internet, while a private IP (the RFC1918 ranges 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16) only works internally and is translated outward through NAT.

Assignment is either static (manually configured, common on servers and infrastructure) or dynamic via DHCP, which is the default for clients in home and enterprise networks. Example: a laptop may hold the private address 192.168.1.42 internally and share the public address 203.0.113.10 with the rest of the household through NAT.