In the Internet addressing architecture, the Internet Engineering Task Force (IETF) and the Internet Assigned Numbers Authority (IANA) have reserved various Internet Protocol (IP) addresses for special purposes.[1]
IPv4 designates special usage or applications for various addresses or address blocks:[1][2]
Address block | Address range | Number of addresses | Scope | Description |
---|---|---|---|---|
0.0.0.0/8 | 0.0.0.0–0.255.255.255 | 16777216 | Software | Current (local, "this") network[1] |
10.0.0.0/8 | 10.0.0.0–10.255.255.255 | 16777216 | Private network | Used for local communications within a private network[3] |
100.64.0.0/10 | 100.64.0.0–100.127.255.255 | 4194304 | Private network | Shared address space[4] for communications between a service provider and its subscribers when using a carrier-grade NAT |
127.0.0.0/8 | 127.0.0.0–127.255.255.255 | 16777216 | Host | Used for loopback addresses to the local host[1] |
169.254.0.0/16 | 169.254.0.0–169.254.255.255 | 65536 | Subnet | Used for link-local addresses[5] between two hosts on a single link when no IP address is otherwise specified, such as would have normally been retrieved from a DHCP server |
172.16.0.0/12 | 172.16.0.0–172.31.255.255 | 1048576 | Private network | Used for local communications within a private network[3] |
192.0.0.0/24 | 192.0.0.0–192.0.0.255 | 256 | Private network | IETF Protocol Assignments, DS-Lite (/29)[1] |
192.0.2.0/24 | 192.0.2.0–192.0.2.255 | 256 | Documentation | Assigned as TEST-NET-1, documentation and examples[6] |
192.88.99.0/24 | 192.88.99.0–192.88.99.255 | 256 | Internet | Reserved.[7] Formerly used for IPv6 to IPv4 relay[8] (included IPv6 address block 2002::/16). |
192.168.0.0/16 | 192.168.0.0–192.168.255.255 | 65536 | Private network | Used for local communications within a private network[3] |
198.18.0.0/15 | 198.18.0.0–198.19.255.255 | 131072 | Private network | Used for benchmark testing of inter-network communications between two separate subnets[9] |
198.51.100.0/24 | 198.51.100.0–198.51.100.255 | 256 | Documentation | Assigned as TEST-NET-2, documentation and examples[6] |
203.0.113.0/24 | 203.0.113.0–203.0.113.255 | 256 | Documentation | Assigned as TEST-NET-3, documentation and examples[6] |
224.0.0.0/4 | 224.0.0.0–239.255.255.255 | 268435456 | Internet | In use for multicast[10] (former Class D network) |
233.252.0.0/24 | 233.252.0.0–233.252.0.255 | 256 | Documentation | Assigned as MCAST-TEST-NET, documentation and examples (Note that this is part of the above multicast space.)[10][11] |
240.0.0.0/4 | 240.0.0.0–255.255.255.254 | 268435455 | Internet | Reserved for future use[12] (former Class E network) |
255.255.255.255/32 | 255.255.255.255 | 1 | Subnet | Reserved for the "limited broadcast" destination address[1] |
IPv6 assigns special uses or applications for various IP addresses:[1]
Address block (CIDR) | First address | Last address | Number of addresses | Usage | Purpose |
---|---|---|---|---|---|
::/128 | :: | :: | 1 | Software | Unspecified address |
::1/128 | ::1 | ::1 | 1 | Host | Loopback address—a virtual interface that loops all traffic back to itself, the local host |
::ffff:0:0/96 | ::ffff:0.0.0.0 ::ffff:0:0 | ::ffff:255.255.255.255 ::ffff:ffff:ffff | 232 | Software | IPv4-mapped addresses |
::ffff:0:0:0/96 | ::ffff:0:0.0.0.0 ::ffff:0:0:0 | ::ffff:0:255.255.255.255 ::ffff:0:ffff:ffff | 232 | Software | IPv4-translated addresses |
64:ff9b::/96 | 64:ff9b::0.0.0.0 64:ff9b::0:0 | 64:ff9b::255.255.255.255 64:ff9b::ffff:ffff | 232 | The global Internet | IPv4/IPv6 translation[13] |
64:ff9b:1::/48 | 64:ff9b:1:: | 64:ff9b:1:ffff:ffff:ffff:ffff:ffff | 280, with 248 for each IPv4 | Private internets | IPv4/IPv6 translation[14] |
100::/64 | 100:: | 100::ffff:ffff:ffff:ffff | 264 | Routing | Discard prefix[15] |
2001::/32 | 2001:: | 2001:0:ffff:ffff:ffff:ffff:ffff:ffff | 296 | The global Internet | Teredo tunneling[16] |
2001:20::/28 | 2001:20:: | 2001:2f:ffff:ffff:ffff:ffff:ffff:ffff | 2100 | Software | ORCHIDv2[17] |
2001:db8::/32 | 2001:db8:: | 2001:db8:ffff:ffff:ffff:ffff:ffff:ffff | 296 | Documentation | Addresses used in documentation and example source code[18] |
2002::/16 | 2002:: | 2002:ffff:ffff:ffff:ffff:ffff:ffff:ffff | 2112 | The global Internet | The 6to4 addressing scheme (deprecated)[7] |
3fff::/20 | 3fff:: | 3fff:fff:ffff:ffff:ffff:ffff:ffff:ffff | 2108 | Documentation | Addresses used in documentation and example source code[19] |
5f00::/16 | 5f00:: | 5f00:ffff:ffff:ffff:ffff:ffff:ffff:ffff | 2112 | Routing | IPv6 Segment Routing (SRv6)[20] |
fc00::/7 | fc00:: | fdff:ffff:ffff:ffff:ffff:ffff:ffff:ffff | 2121 | Private internets | Unique local address[21] |
fe80::/64 from fe80::/10 | fe80:: | fe80::ffff:ffff:ffff:ffff | 264 | Link | Link-local address |
ff00::/8 | ff00:: | ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff | 2120 | The global Internet | Multicast address |