0.0.0.0
0.0.0.0 stands for a non-routable address or an unknown packet in the Internet Protocol Version 4 (IPv4).
Servers often use this address as a placeholder for all of the local computer's IP addresses. If the server has two IP addresses, e.g. B. 192.168.5.10 and 10.17.0.12, and the server responds to this address, it can be reached on both IP addresses.
If a routing table has an entry with 0.0.0.0, this is often the standard route for establishing connections to computers outside of your own network.
use
Other uses of 0.0.0.0 include:
- The address to which a PC assigns itself if it has received neither a dynamic nor a static IP address, for example when sending a broadcast request "DHCPDISCOVER" .
- The address that the PC assigns itself if a DHCPDISCOVER has failed. This was exchanged in Microsoft systems with the APIPA mechanism (comparable to the RFC of the IETF ), cf. Zeroconf # implementations .
- One way to specify “any reachable IPv4 host”. This is mainly used in firewalls and routing tables.
- A way to explicitly specify that a host is unreachable.
IPv6
Under IPv6 , the address 0.0.0.0 is represented by "::", the short notation of 0000: 0000: 0000: 0000: 0000: 0000: 0000: 0000. Under IPv6 the address has the same usage as under IPv4.