IP Address.

A numeric identifier assigned to a network interface for routing across IP networks: 32 bits in IPv4 (RFC 791) or 128 bits in IPv6 (RFC 8200). It belongs to the Network Security category of cybersecurity.

A numeric identifier assigned to a network interface for routing across IP networks: 32 bits in IPv4 (RFC 791) or 128 bits in IPv6 (RFC 8200).

An IP address uniquely identifies a network interface within an IP routing domain. IPv4 addresses are 32 bits, typically written as four decimal octets (e.g., 203.0.113.42), and are largely exhausted, prompting widespread use of NAT and reserved private ranges in RFC 1918. IPv6 addresses are 128 bits, written as eight 16-bit hex groups with :: zero compression (e.g., 2001:db8::1), restoring end-to-end addressing. Addresses can be unicast, multicast, or broadcast (IPv4) / anycast (IPv6) and are paired with a prefix length to define the subnet. From a security standpoint, IP addresses are reputation signals, attribution clues, and ACL targets, but they are not user identities and can be spoofed, NATed, or shared via CG-NAT.

Defences for IP Address typically combine technical controls and operational practices, as detailed in the full definition above.

Common alternative names include: IPv4 address, IPv6 address.