64:ff9b:1::/48

64

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

Short answer

64:ff9b:1::/48 is for local-use IPv4/IPv6 translation inside a network.

Block	64:ff9b:1::/48
First – last	64:ff9b:1:: – 64:ff9b:1:ffff:ffff:ffff:ffff:ffff
Size	a /48 (2^80 addresses)
Name in the registry	IPv4-IPv6 Translat.
Defined in	RFC 8215
Allocated	2017-06
Valid as source / destination	True / True
Forwardable	True
Globally reachable	False

What it means

RFC 8215 reserves this prefix for NAT64 translators that a network runs for its own use, rather than the global well-known prefix.

It is not routed on the public internet.

Want the address websites actually see for you? Open the Truth Check.