Reserved IP addresses

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

This section is transcluded from IPv4#Special-use addresses. (edit | history)

IPv4 designates special usage or applications for various addresses or address blocks:^[1][2]

Special address blocks

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 (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

This section is transcluded from IPv6 address#Special addresses. (edit | history)

IPv6 assigns special uses or applications for various IP addresses:^[1]

Special address blocks

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
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

See also

• Bogon filtering
• Martian packet
• Classless Inter-Domain Routing (CIDR)
• Top-level domain § Reserved domains