====== Ubuntu - IPv6 - Special IPv6 address ranges ======

^IPv6 address^Prefix length (bits)^Description^Notes^
|::|128|unspecified|Used for default route and router solicitations. cf. 0.0.0.0 in IPv4|
|::1|128|loopback address|cf. 127.0.0.1 in IPv4|
|::ffff:a.b.c.d|96|IPv4 mapped IPv6 address|The lower 32 bits are the IPv4 address. Used in socket API's to represent IPv4 hosts.|
|fe80::|10|link-local|Unroutable autoconfigured addresses used on a LAN, e.g. for DHCPv6|
|fc00::|7|unique local|Addresses used only within an autonomous system, unroutable globally. Cf. RFC 1918 addresses such as used in NAT.|
|ff00::|8|multicast| |
|2000::|3|global unicast|All global unicast addresses currently begin with 2.|

----

Some IPv6 address prefixes have been deprecated, and should no longer be used.

^Deprecated IPv6 address^Prefix length (bits)^Description^Notes^
|3ffe::|16|6bone prefix|Used 1998-2006.|
|::a.b.c.d|96|embedded IPv4|96 zero bits followed by 32 IPv4 bits. Also called “IPv4 compatible IPv6 address”. Replaced by mapped addresses.|
|fec0::|10|site-local|Replaced by Unique Local Addresses|

----

Some address prefixes are special use:

^Special IPv6 address^Prefix length (bits)^Description^Notes^
|2001:db8::|32|documentation examples|Not to be routed.|
|2001:0::|32|Teredo tunnels|The remaining bits come from a Teredo server and the client NAT device.|
|2002::|16|6to4 tunnels|The next 32 bits are the client IPv4 address|