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Special address blocks
Address block Address range Number of addresses Scope Description– 232-8 = 224 = 16777216 Software Current network[1] (only valid as source address).– 16777216 Private network Used for local communications within a private network.[2]– 4194304 Private network Shared address space[3] for communications between a service provider and its subscribers when using a carrier-grade NAT.– 16777216 Host Used for loopback addresses to the local host.[1]– 65536 Subnet Used for link-local addresses[4] 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.– 1048576 Private network Used for local communications within a private network.[2]– 256 Private network IETF Protocol Assignments.[1]– 256 Documentation Assigned as TEST-NET-1, documentation and examples.[5]– 256 Internet Reserved.[6] Formerly used for IPv6 to IPv4 relay[7] (included IPv6 address block 2002::/16).– 65536 Private network Used for local communications within a private network.[2]– 131072 Private network Used for benchmark testing of inter-network communications between two separate subnets.[8]– 256 Documentation Assigned as TEST-NET-2, documentation and examples.[5]– 256 Documentation Assigned as TEST-NET-3, documentation and examples.[5]– 268435456 Internet In use for IP multicast.[9] (Former Class D network).– 268435456 Internet Reserved for future use.[10] (Former Class E network). 1 Subnet Reserved for the “limited broadcast” destination address.[1][11]


Special address blocks
Address block (CIDR) First address Last address Number of addresses Usage Purpose
::/0 :: ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 2128 Routing Default route.
::/128 :: 1 Software Unspecified address.
::1/128 ::1 1 Host Loopback address to the local host.
::ffff:0:0/96 ::ffff: ::ffff: 2128-96 = 232 = 4294967296 Software IPv4 mapped addresses.
::ffff:0:0:0/96 ::ffff:0: ::ffff:0: 232 Software IPv4 translated addresses.
64:ff9b::/96 64:ff9b:: 64:ff9b:: 232 Global Internet IPv4/IPv6 translation.[12]
100::/64 100:: 100::ffff:ffff:ffff:ffff 264 Routing Discard prefix.[13]
2001::/32 2001:: 2001::ffff:ffff:ffff:ffff:ffff:ffff 296 Global Internet Teredo tunneling.
2001:20::/28 2001:20:: 2001:2f:ffff:ffff:ffff:ffff:ffff:ffff 2100 Software ORCHIDv2.[14]
2001:db8::/32 2001:db8:: 2001:db8:ffff:ffff:ffff:ffff:ffff:ffff 296 Documentation Addresses used in documentation and example source code.
2002::/16 2002:: 2002:ffff:ffff:ffff:ffff:ffff:ffff:ffff 2112 Global Internet The 6to4 addressing scheme (now deprecated).[6]
fc00::/7 fc00:: fdff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 2121 Private network Unique local address.[15]
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 address.

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