A special-use domain name is a domain name that is defined and reserved in the hierarchy of the Domain Name System of the Internet for special purposes. The designation of a reserved special-use domain is authorized by the Internet Engineering Task Force (IETF) and executed, maintained, and published by the Internet Assigned Numbers Authority (IANA).[1]
The following list comprises the domain names list by IANA in the category of special-use domain names.[2]
| Domain | Purpose | Authority document |
|---|---|---|
| alt. | preventing name collisions with DNS | RFC 9476 |
| 6tisch.arpa. | IETF 6TiSH working group | RFC 9031 |
| 10.in-addr.arpa. | private network reverse mapping | RFC 6761 |
| 16.172.in-addr.arpa. | ||
| 17.172.in-addr.arpa. | ||
| 18.172.in-addr.arpa. | ||
| 19.172.in-addr.arpa. | ||
| 20.172.in-addr.arpa. | ||
| 21.172.in-addr.arpa. | ||
| 22.172.in-addr.arpa. | ||
| 23.172.in-addr.arpa. | ||
| 24.172.in-addr.arpa. | ||
| 25.172.in-addr.arpa. | ||
| 26.172.in-addr.arpa. | ||
| 27.172.in-addr.arpa. | ||
| 28.172.in-addr.arpa. | ||
| 29.172.in-addr.arpa. | ||
| 30.172.in-addr.arpa. | ||
| 31.172.in-addr.arpa. | ||
| 168.192.in-addr.arpa. | ||
| 170.0.0.192.in-addr.arpa. | NAT64 prefix discovery (RFC 7050) | RFC 8880 |
| 171.0.0.192.in-addr.arpa. | ||
| ipv4only.arpa. | ||
| 254.169.in-addr.arpa. | Use in multicast DNS (mDNS) | RFC 6762 |
| 8.e.f.ip6.arpa. | ||
| 9.e.f.ip6.arpa. | ||
| a.e.f.ip6.arpa. | ||
| b.e.f.ip6.arpa. | ||
| home.arpa. | Non-unique use on residential networks | RFC 8375 |
| example. | documentation, tutorials, etc. | RFC 6761 |
| example.com. | use in documentation, tutorials, testing | RFC 6761 |
| example.net. | ||
| example.org. | ||
| invalid. | Avoidance of confusion and errors per RFC 2606 | RFC 6761 |
| local. | Used for Multicast DNS | RFC 6762 (Section 3) |
| localhost. | Reserved to avoidance of confusion and errors | RFC 6761 |
| onion. | Anonymous onion service | RFC 7686 |
| test. | Avoidance of confusion, allowing use for documentation and network testing | RFC 6761 |
