IPv6 prefix
64:ff9b:0:0:0:0:0:0/96
Special-Purpose Address Block: Network Address Translation 64 (NAT64) Well-Known Prefix
- Public routing
- expected to be globally reachable
- IP Prefix (CIDR)
- 64:ff9b:0:0:0:0:0:0/96
- Address Count
- 4.295 x 10^9
This prefix is used by NAT64 systems to synthesize IPv6 addresses that represent IPv4 destinations.
IANA marks this prefix globally reachable. Whether a specific address works depends on the NAT64 deployment and routing policy.
A system administrator may see it in IPv6-only networks that need to reach IPv4 services. The last 32 bits usually carry the embedded IPv4 address.
Firewall tip: allow it only where NAT64 translation is expected. Otherwise treat it as translation infrastructure rather than a normal client subnet.
| Block | Name |
|---|---|
| 0:0:0:0:0:0:0:1/128 | Loopback |
| 0:0:0:0:0:0:0:0/128 | Unspecified Address |
| 0:0:0:0:0:ffff:0:0/96 | IPv4-Mapped Address |
| 64:ff9b:1:0:0:0:0:0/48 | Network Address Translation 64 (NAT64) Local-Use Prefix |
| 100:0:0:0:0:0:0:0/64 | Discard-Only Address Block |
| 100:0:0:1:0:0:0:0/64 | Dummy IPv6 Prefix |
| 2001:0:0:0:0:0:0:0/23 | IETF (Internet Engineering Task Force) Protocol Assignments |
| 2001:0:0:0:0:0:0:0/32 | Teredo |
| 2001:1:0:0:0:0:0:1/128 | Port Control Protocol (PCP) Anycast |
| 2001:1:0:0:0:0:0:2/128 | Traversal Using Relays around NAT (TURN) Anycast |
| 2001:1:0:0:0:0:0:3/128 | DNS-SD Service Registration Protocol Anycast |
| 2001:2:0:0:0:0:0:0/48 | Benchmarking |
| 2001:3:0:0:0:0:0:0/32 | Automatic Multicast Tunneling (AMT) |
| 2001:4:112:0:0:0:0:0/48 | Autonomous System 112 (AS112) Service |
| 2001:10:0:0:0:0:0:0/28 | Deprecated Overlay Routable Cryptographic Hash Identifiers (ORCHID) |
| 2001:20:0:0:0:0:0:0/28 | Overlay Routable Cryptographic Hash Identifiers Version 2 (ORCHIDv2) |
| 2001:30:0:0:0:0:0:0/28 | Drone Remote ID Protocol Entity Tags (DETs) |
| 2001:db8:0:0:0:0:0:0/32 | Documentation (RFC 3849) |
| 2002:0:0:0:0:0:0:0/16 | 6to4 |
| 2620:4f:8000:0:0:0:0:0/48 | Direct Delegation Autonomous System 112 (AS112) Service |
| 3fff:0:0:0:0:0:0:0/20 | Documentation (RFC 9637) |
| 5f00:0:0:0:0:0:0:0/16 | Segment Routing over IPv6 (SRv6) Segment Identifiers |
| fc00:0:0:0:0:0:0:0/7 | Unique Local Address |
| fe80:0:0:0:0:0:0:0/10 | Link-Local Unicast |
| 0:0:0:0:0:0:0:0/8 | Reserved by IETF (Internet Engineering Task Force) |
| 0:0:0:0:0:0:0:0/96 | Deprecated IPv4-Compatible IPv6 Prefix |
| fec0:0:0:0:0:0:0:0/10 | Deprecated Site-Local Unicast |
| ff00:0:0:0:0:0:0:0/8 | Multicast |