.invalid

The name invalid is reserved by the Internet Engineering Task Force (IETF) in RFC 2606 (June 1999) as a domain name that may not be installed as a top-level domain in the Domain Name System (DNS) of the Internet. In 1999, the Internet Engineering Task Force reserved the DNS labels , , , and so that they may not be installed into the root zone of the Domain Name System. The reasons for reservation of these top-level domain names is to reduce the likelihood of conflict and confusion. This allows the use of these names for either documentation purposes or in local testing scenarios. This top-level domain is sometimes used as a pseudo domain name in Uniform Resource Identifiers (URIs) to convey either an error condition or in use of privacy protection. A notable instance of this usage is in the Session Initiation Protocol (SIP) where the domain name in a SIP URI indicates hiding of a caller's identity.