IP addresses in the range:
0.0.0.0
The address "0.0.0.0" used mean the same as "255.255.255.255", which is the "local broadcast". Also, many systems use this address to mean "no address". For example, several intrusion detection systems use this address in the cases of IP spoofing where the attacking address isn't known.
0.x.x.x
Many protocol stacks use this address range for built-in properties. It should never be used external to a machine.
127.0.0.1
This is the loopback address. The command "ping 127.0.0.1" is generally used to see if the TCP/IP stack works at all. This just causes the machine to ping itself.
127.x.x.x
Actually, any 127.x.x.x address can be used to refer to the loopback address.
192.0.2.x
This address range is earmarked for written examples. Books and documentation that refers to IP addresses should use this range. It is similar to the phone number 555-XXXX seen in movies.
169.254.x.x
This address range has been reserved for use when DHCP configuration fails.
- 0.0.0.0 - 0.255.255.255 (RESERVED-1)
- 85.0.0.0 - 95.255.255.255 (RESERVED-11)
- 10.0.0.0 - 10.255.255.255 (RESERVED-10)
- 127.0.0.0 - 127.255.255.255 (LOOPBACK)
- 169.254.0.0 - 169.254.255.255 (LINKLOCAL)
- 172.16.0.0 - 172.31.255.255
- 192.0.0.0 - 192.0.255.255 (RESERVED-192)
- 192.0.128.0 - 192.0.255.255 (IANA Special Use)
- 192.168.0.0 - 192.168.255.255 (IANA-CBLK1)
- 240.0.0.0 - 255.255.255.255 (RESERVED-240)
Machines with these addresses do not have direct access to the Internet (they cannot "ping"). In order to access Internet resources, they must go through a proxy firewall.
Furthermore, there are other networking addresses that should never be configured
In much the same way, the DNS names "example.net" and "example.com" have been reserved for documentation purposes.
Increasingly, routers on the Internet are being assigned "private" addresses. These addresses are used for communication with the router itself. As a result, packets sent by the router itself will use these private address. Many filters block these private addresses, resulting in these connections being dropped.
Updated On: 04.03.26