Sign inMonitor a domain
64:ff9b::/96

64

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

Short answer

64:ff9b::/96 is the well-known NAT64 prefix: IPv6 addresses that stand for IPv4 destinations.

Block64:ff9b::/96
First – last64:ff9b:: – 64:ff9b::ffff:ffff
Sizea /96 (2^32 addresses)
Name in the registryIPv4-IPv6 Translat.
Defined inRFC 6052
Allocated2010-10
Valid as source / destinationTrue / True
ForwardableTrue
Globally reachableTrue

What it means

RFC 6052 reserves 64:ff9b::/96 so that an IPv6-only network can reach IPv4 sites through a NAT64 gateway: the last 32 bits are the IPv4 address. Many mobile carriers run IPv6-only networks this way.

If you see it, your provider is translating your traffic to IPv4 at its gateway.

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

Sources

  1. IANA IPv6 Special-Purpose Address Registry (CC0) · checked 2 Nov 2026
  2. RFC 6052