Unspecified address
0.0.0.0/8
0.0.0.0/8 is the “this network” block (RFC 1122). It isn't routed on the public internet, so there's nothing public to look up. In a server's settings it means every address the machine has. In hosts files and blocklists it means nowhere.
At a glance
- Block
- 0.0.0.0/8
- Defined in
- RFC 1122
- On the public internet
- No
About this block
Addresses in 0.0.0.0/8 mean “this network” and can only be used as a source while a device is still working out its own address. They're never a destination on the internet.
0.0.0.0 itself means “no particular address”.
Where you'll see it
- Server settings: listening on 0.0.0.0 means accepting connections on every address the machine has.
- Hosts files and DNS blocklists, which point unwanted names at 0.0.0.0 so they go nowhere.
- Routing tables, where 0.0.0.0/0 is the default route.