fc00::/7

fc00

Last updated 2 Nov 2026 from the IANA IPv6 Special-Purpose Address Registry

Short answer

fc00::/7 is unique local IPv6: like private IPv4, it only exists inside a network.

Block	fc00::/7
First – last	fc00:: – fdff:ffff:ffff:ffff:ffff:ffff:ffff:ffff
Size	a /7 (2^121 addresses)
Name in the registry	Unique-Local
Defined in	RFC 4193; RFC 8190
Allocated	2005-10
Valid as source / destination	True / True
Forwardable	True
Globally reachable	False

What it means

RFC 4193 defines unique local addresses, in practice fd00::/8 with a random 40-bit prefix, for use inside a home or company. They are not routed on the internet.

Your public IPv6 address is a different one; open the Truth Check to see it.

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Sources

IANA IPv6 Special-Purpose Address Registry (CC0) · checked 2 Nov 2026
RFC 4193; RFC 8190