Glossary · Internet & Web

IPv4 (Internet Protocol version 4)

IPv4 is the older internet addressing system using 32-bit addresses written as four numbers like 192.0.2.1, with about 4.3 billion possible values.

Updated October 6, 2026

IPv4 is version 4 of the Internet Protocol, which identifies devices with 32-bit addresses written as four decimal numbers separated by dots. The format allows roughly 4.3 billion unique addresses.

Why it matters

IPv4 still carries most traffic, but the available addresses have been exhausted at the registry level, so providers share addresses using NAT and trade blocks. Websites are normally given an A record pointing to an IPv4 address, often alongside an AAAA record for IPv6.

Dual-stack setups run IPv4 and IPv6 side by side, which is the practical approach for most sites today.

Example

192.0.2.1  ->  four 8-bit numbers (0-255)
DNS: example.com.  IN  A  192.0.2.1

Private ranges such as 10.0.0.0/8 and 192.168.0.0/16 are reserved for internal networks.

Common mistakes

  • Writing numbers above 255 in an address, which is invalid.
  • Mixing up public and private IPs when configuring port forwarding or firewalls.
  • Ignoring IPv6 and leaving AAAA records pointing to a dead server.

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