Special-use domain name

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]

Reserved domain names

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 6TiSCH 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

See also

• Internet portal

• Reserved top-level domains