IPv4only

IPv4only is a term used to describe networks, systems, or devices that provide native connectivity using only the Internet Protocol version 4 (IPv4) and do not implement IPv6 in any meaningful way. In such environments, endpoints are assigned IPv4 addresses and routing is performed without IPv6. The term is descriptive rather than a formal standard and is commonly contrasted with dual-stack networks that run IPv4 and IPv6 in parallel, and with IPv6-only deployments that do not carry IPv4.

Technical characteristics include reliance on 32-bit IPv4 addresses, private address space (RFC 1918) behind Network Address Translation (NAT), and compatibility with a broad set of legacy equipment and software. Because IPv4 addresses became scarce, many IPv4-only networks use NAT and carefully managed address plans to serve multiple devices. IPv4-only does not inherently prevent access to modern services, but direct native access to IPv6-only resources is not possible without translation or tunneling.

Transition and interoperation: To communicate with IPv6 hosts or networks, IPv4-only environments typically rely on external transition mechanisms such as proxies, gateways, or tunnels provided by service providers, or they may migrate toward dual-stack configurations. The move to IPv6 is widely encouraged to ease address scarcity and to enable features that are native to IPv6.

Management and planning: Migration involves assessing device support for IPv6, updating firmware or operating systems, enabling IPv6 addressing in routers, configuring DHCPv6, and ensuring DNS and application compatibility. Some organizations maintain IPv4-only segments temporarily while routing policies and procurement align with IPv6 deployment goals. See also IPv6, dual-stack, and transition mechanisms.