IPv6 address space

The type of an IPv6 address is identified by the high-order bits of the address as shown in Table 1.

Table 1. Address type representation
Address type	Binary prefix	IPv6 notation
Unspecified	00...0 (128 bits)	::/128
Loopback	00...1 (128 bits)	::1/128
Unique local unicast	1111110	FC00::/7
Multicast	11111111	FF00::/8
Link-local unicast	1111111010	FE80::/10
Global unicast aggregatable	(everything else)

Anycast addresses are taken from the unicast address spaces (of any scope) and are not syntactically distinguishable from unicast addresses. Anycast is described as a cross between unicast and multicast. Like multicast, multiple nodes might be listening on an anycast address. Like unicast, a packet sent to an anycast address is delivered to one (and only one) of those nodes. The exact node to which it is delivered is based on the IP routing tables in the network.

For more information about different IPv6 addresses, see Categories of IPv6 addresses.