Editing IP address (section)

===Private addresses===
Early network design, when global end-to-end connectivity was envisioned for communications with all Internet hosts, intended that IP addresses be globally unique. However, it was found that this was not always necessary as private networks developed and public address space needed to be conserved.

Computers not connected to the Internet, such as factory machines that communicate only with each other via [[TCP/IP]], need not have globally unique IP addresses. Today, such private networks are widely used and typically connect to the Internet with [[network address translation]] (NAT), when needed.

Three non-overlapping ranges of IPv4 addresses for private networks are reserved.<ref name=rfc1918/> These addresses are not routed on the Internet and thus their use need not be coordinated with an IP address registry. Any user may use any of the reserved blocks. Typically, a network administrator will divide a block into subnets; for example, many [[residential gateway|home routers]] automatically use a default address range of {{IPaddr|192.168.0.0}} through {{IPaddr|192.168.0.255}} ({{IPaddr|192.168.0.0|24}}).
{{trim|{{#section:IPv4|IPv4-private-networks}}}}