Reserved IPv4 addresses

The Internet Assigned Numbers Authority (IANA) has set aside a number of IPv4 address sectors for special purposes. But because the IPv4 address space has turned out to be insufficient and some reserved sectors are hardly used, some of this space has been made available again. RIPE organizes the issue of IP addresses in Europe. Users generally do not get them directly, however, but rather from their provider.
Information on addresses not listed here is provided at our whois search.

0.0.0.0/8

Host in "this" network. The address 0.0.0.0/32 designates the host itself. This address can only be used for source addresses, for instance for the assignment of DHCP and PPP before the host has received an address. Defined in RFC 5735, page 3.

10.0.0.0/8

Addresses for private networks; address need not be registered for use. They may not, however, be used on the public internet. RFC 1918 defines how these addresses are to be handled.

127.0.0.0/8

Loopback addresses: Each packet sent to one of these addresses is sent back internally instead of leaving the host. Defined in RFC 1700, page 4.

169.254.0.0/16

Addresses for automatic configuration (APIPA, Zeroconf). These addresses should only occur within this network. Defined in RFC 3927.

172.16.0.0/12

Addresses for private networks; address need not be registered for use. They may not, however, be used on the public internet. RFC 1918 defines how these addresses are to be handled.

192.0.0.0/24

Reserved, will be made publicly available if need be. Defined in RFC 5736.

192.0.2.0/24, 198.51.100.0/24, 203.0.113.0/24

Reserved as example addresses to be used in documentation (in a similar way the domain names example.com and example.net from RFC 2606 are used). Addresses in this range may not be used on the public Internet. Defined in RFC 5737.

192.88.99.0/24

RFC 3068 defines addresses that connect IPv6 networks via IPv4 ("6to4 anycast address").

192.168.0.0/16

Addresses for private networks; address need not be registered for use. They may not, however, be used on the public Internet. RFC 1918 defines how these addresses are to be handled.

198.18.0.0/15

Addresses for tests of network components. Defined in RFC 2544.

224.0.0.0/4

Multicast for the broadcasting of data from one sender to a select group of recipients. The IANA specifies the use of individual multicast addresses. Defined in RFC 3171.

240.0.0.0/4

Reserved for later use. Defined in RFC 1112

255.255.255.255/32

Address for limited broadcasting. It can only be used as a target address, and packets with that address should not be routed from the network they come from. Defined in RFC 1700, page 4.

Formerly reserved IPv4 ranges

14.0.0.0/8

Was reserved for a service for the transmission of IP packets via "Public Data Networks" (PDNs), such as protocol X.25 detailed in RFC 1356. Released in RFC 5735 as regular address space.

24.0.0.0/8

Was reserved for IP over TV systems, but managed by The American Registry for Internet Numbers (ARIN) now manages this address range. Defined in RFC 3330. Released in RFC 5735.

39.0.0.0/8

In 1995, this address range was reserved for the "Class A Subnet Experiment" (see RFC 1797). Released in RFC 5735.

128.0.0.0/16

Defined in RFC 3330. Released in RFC 5735.

191.255.0.0/16

Defined in RFC 3330. Released in RFC 5735.

223.255.255.0/24

Defined in RFC 3330. Released in RFC 5735.