Reserved IP addresses

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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. These IP addresses may be used for maintenance of routing tables, multicast, operation under failure modes, or to provide addressing space for public, unrestricted uses.

The IETF sets the guidelines for use of the IP address space in RFC specifications, and directs IANA to implement the policies. Reserved IP addresses tend to belong to three categories: addresses that are globally unique, addresses that are unique to the subnet, and addresses that are only relevant to the host using the address.[citation needed]

Reserved IPv4 addresses[edit]

CIDR Address Range Number of Addresses Scope Purpose
0.0.0.0/8 0.0.0.0 –
0.255.255.255
16,777,216 software Used for broadcast messages to the current ("this") network as specified by RFC 1700, page 4.
10.0.0.0/8 10.0.0.0 –
10.255.255.255
16,777,216 private network Used for local communications within a private network as specified by RFC 1918.
100.64.0.0/10 100.64.0.0 –
100.127.255.255
4,194,304 private network Used for communications between a service provider and its subscribers when using a Carrier-grade NAT, as specified by RFC 6598.
127.0.0.0/8 127.0.0.0 –
127.255.255.255
16,777,216 host Used for loopback addresses to the local host, as specified by RFC 990.
169.254.0.0/16 169.254.0.0 –
169.254.255.255
65,536 subnet Used for autoconfiguration 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, as specified by RFC 6890.
172.16.0.0/12 172.16.0.0 –
172.31.255.255
1,048,576 private network Used for local communications within a private network as specified by RFC 1918
192.0.0.0/29 192.0.0.0 –
192.0.0.7
8 private network Used for the DS-Lite transition mechanism as specified by RFC 6333
192.0.2.0/24 192.0.2.0 –
192.0.2.255
256 documentation Assigned as "TEST-NET" in RFC 5737 for use solely in documentation and example source code and should not be used publicly.
192.88.99.0/24 192.88.99.0 –
192.88.99.255
256 Internet Used by 6to4 anycast relays as specified by RFC 3068.
192.168.0.0/16 192.168.0.0 –
192.168.255.255
65,536 private network Used for local communications within a private network as specified by RFC 1918.
198.18.0.0/15 198.18.0.0 –
198.19.255.255
131,072 private network Used for testing of inter-network communications between two separate subnets as specified in RFC 2544.
198.51.100.0/24 198.51.100.0 –
198.51.100.255
256 documentation Assigned as "TEST-NET-2" in RFC 5737 for use solely in documentation and example source code and should not be used publicly.
203.0.113.0/24 203.0.113.0 –
203.0.113.255
256 documentation Assigned as "TEST-NET-3" in RFC 5737 for use solely in documentation and example source code and should not be used publicly.
224.0.0.0/4 224.0.0.0 –
239.255.255.255
268,435,456 Internet Reserved for multicast assignments as specified in RFC 5771.

233.252.0.0/24 is assigned as "MCAST-TEST-NET" for use solely in documentation and example source code.

240.0.0.0/4 240.0.0.0 –
255.255.255.254
268,435,455 n/a Reserved for future use, as specified by RFC 6890.
255.255.255.255/32 255.255.255.255 1 n/a Reserved for the "limited broadcast" destination address, as specified by RFC 6890.

Reserved IPv6 addresses[edit]

CIDR Address Range Number of Addresses scope Purpose
::/128 :: 1 software Unspecified address
::1/128 ::1 1 host loopback address to the local host.
::ffff:0:0/96 ::ffff:0.0.0.0 –
::ffff:255.255.255.255
232 software IPv4 mapped addresses
100::/64 100:: –
100::ffff:ffff:ffff:ffff
264 Discard Prefix RFC 6666
64:ff9b::/96 64:ff9b::0.0.0.0 –
64:ff9b::255.255.255.255
232 global Internet[1] IPv4/IPv6 translation (RFC 6052)
2001::/32 2001:: –
2001::ffff:ffff:ffff:ffff:ffff:ffff
296 global Teredo tunneling
2001:10::/28 2001:10:: –
2001:1f:ffff:ffff:ffff:ffff:ffff:ffff
2100 software Overlay Routable Cryptographic Hash Identifiers (ORCHID)
2001:db8::/32 2001:db8:: –
2001:db8:ffff:ffff:ffff:ffff:ffff:ffff
296 documentation Addresses used in documentation
2002::/16 2002:: –
2002:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2112 global Internet 6to4
fc00::/7 fc00:: –
fdff:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2121 private network Unique local address
fe80::/10 fe80:: -
febf:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2118 link Link-local address
ff00::/8 ff00:: –
ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2120 global Internet Multicast

References[edit]

  1. ^ RFC 6052 section 3.2