2025-10-23 The IPv6 address management function was formally delegated to IANA in December 1995 . The registration procedure was confirmed with the IETF Chair in March 2010. As stated in , IANA should limit its allocation of IPv6-unicast address space to the range of addresses that start with binary value 001. The rest of the global unicast address space (approximately 85% of the IPv6 address space) is reserved for future definition and use, and is not to be assigned by IANA at this time. While was obsoleted by , the guidance provided to IANA did not change regarding the allocation of IPv6 unicast addresses. Internet Protocol Version 6 Address Space (pursuant to IESG decision) IETF Review ::/8 Reserved by IETF This range has been partially allocated. See IPv6 Special-Purpose Address Space for details. ::/96, formerly defined as the "IPv4-compatible IPv6 address" prefix, was deprecated by . 100::/8 Reserved by IETF This range has been partially allocated. See IPv6 Special-Purpose Address Space for details. 200::/7 Reserved by IETF Deprecated as of December 2004 . Formerly an OSI NSAP-mapped prefix set . 400::/6 Reserved by IETF 800::/5 Reserved by IETF 1000::/4 Reserved by IETF 2000::/3 Global Unicast The IPv6 Unicast space encompasses the entire IPv6 address range with the exception of ff00::/8, per . IANA unicast address assignments are currently limited to the IPv6 unicast address range of 2000::/3. IANA assignments from this block are registered in IPv6 Global Unicast Address Space. 4000::/3 Reserved by IETF This range has been partially allocated. See IPv6 Special-Purpose Address Space for details. 5f00::/8 (with 3ffe::/16, as noted at IPv6 Global Unicast Address Space) was used for the 6bone, but returned . 6000::/3 Reserved by IETF 8000::/3 Reserved by IETF a000::/3 Reserved by IETF c000::/3 Reserved by IETF e000::/4 Reserved by IETF f000::/5 Reserved by IETF f800::/6 Reserved by IETF fc00::/7 Unique Local Unicast See IPv6 Special-Purpose Address Space for details. fe00::/9 Reserved by IETF fe80::/10 Link-Scoped Unicast See IPv6 Special-Purpose Address Space for details. fec0::/10 Reserved by IETF Deprecated by in September 2004. Formerly a Site-Local scoped address prefix. ff00::/8 Multicast See IPv6 Multicast Address Space for details.