As is known as the loopback address, is there a shorter term to refer to other than "the IP address who means all IP address on local machine"?

3 Answers 3


Sometimes it is called "wildcard address", INADDR_ANY, or "unspecified address". The official name is "source address for this host on this network" (RFC 5735, Section 3). It must not appear in packets sent to the network under normal circumstances:

This host on this network. MUST NOT be sent, except as a source address as part of an initialization procedure by which the host learns its own IP address.

But if it appears as destination address in incoming packet it should be treated as broadcast address (RFC 1122, Section 3.3.6)


The official name for (or ::0/0) is "the unspecified address".

  • 2
    Per @BMDan's answer, /0 is different from /32.
    – Snekse
    Jun 12, 2017 at 2:52

IPv4 and IPv6 ::0/0

  • is "all addresses"
  • covers every IP on the Internet
  • is used in routing when specifying a default gateway
  • is used firewalls when specifying default rules

is diferent from (is the same as

  • is primarily used when accepting all incoming connections (regardless of the destination IP address or receiving network interface)
  • "the unspecified address"
  • is used on application-level as uninitialized IP address

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