We now summarize the important special cases for Class A, B,Īnd C IP addresses, using the following notation for an IP Lee B's answer is right on, but here's some relevant RFCs in case you're interested. Lastly, when seen in the output of the netstat command (which is what you asked for), it means that a given socket is listening on all the available IP addresses the computer has when a computer has more than one IP address, a socket can be bound only to a specific address and port pair, or to a port and all addresses if you see an IP address there, it means that socket is listening only on that port and that specific address if you see 0.0.0.0, it means it's listening on that port on all addresses of the machine, including the loopback one ( 127.0.0.1).the one used when there is not any more specific route available to a destination address. If used in a routing table, it identifies the default gateway a route to 0.0.0.0 is the default one, i.e.It can't be used as the source address on any IP packet, unless this happens when a computer still doesn't know its own IP address and it's trying to acquire one (classic example: DHCP).
It's not a valid address to be given to an actual network interface, along with any other address in the 0.0.0.0/8 subnet (i.e.
The IP address 0.0.0.0 can have very different meanings, depending on where it's used.
