IP Address

An IP address (Internet Protocol address) is a unique number that identifies a device on a network that runs the Internet Protocol. It plays a dual role: it says which device is involved (identification) and where it sits in the network (addressing), so that data packets reach exactly where they should.

How an IP address works

When a browser connects to a website, the data is split into packets, and each one carries a sender and a destination address. Routers along the way read the destination IP address and pass the packet ever closer to its target — much like a postal service uses a postcode and address. Two versions of the protocol exist: IPv4, written as four numbers (e.g. 192.0.2.10), and the newer IPv6, which solves the shortage of available addresses.

Because people do not memorize strings of digits, in practice we use domain names. The DNS system translates a readable name (e.g. nodea.pl) into its matching IP address — stored in an A record for IPv4 or an AAAA record for IPv6.

IP addresses in practice

Every web server, mail server, or networked device has an IP address assigned to it. In hosting, the server's IP address decides where traffic is sent once a domain resolves; when you move a site to a new VPS, it is this address that changes in the DNS records. IP addresses are also used for firewall filtering, geolocation, rate limiting, and connection diagnostics with tools such as ping and traceroute. In shared environments many sites may use one address (distinguished by the Host header), whereas services that need full control, such as a dedicated mail server or certain certificates, rely on a dedicated IP address bound to a single server.