RFC 2606: Reserved Top Level DNS Names

To reduce the likelihood of conflict and confusion, a few top level domain names are reserved for use in private testing, as examples in documentation, and…

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Outgoing relationships (3 related RFCs)

Informative reference — RFC 1035: Domain names - implementation and specification
Informative reference — RFC 1034: Domain names - concepts and facilities
Informative reference — RFC 1591: Domain Name System Structure and Delegation

Incoming relationships (23 related RFCs)

Updated by, Informatively referenced by — RFC 6761: Special-Use Domain Names
Normatively referenced by — RFC 5782: DNS Blacklists and Whitelists
Normatively referenced by — RFC 6858: Simplified POP and IMAP Downgrading for Internationalized Email
Normatively referenced by — RFC 6616: A Simple Authentication and Security Layer (SASL) and Generic Security Service Application Program Interface (GSS-API) Mechanism for OpenID
Normatively referenced by — RFC 8904: DNS Whitelist (DNSWL) Email Authentication Method Extension
Informatively referenced by — RFC 6895: Domain Name System (DNS) IANA Considerations
Informatively referenced by — RFC 7042: IANA Considerations and IETF Protocol and Documentation Usage for IEEE 802 Parameters
Informatively referenced by — RFC 5737: IPv4 Address Blocks Reserved for Documentation
Informatively referenced by — RFC 4343: Domain Name System (DNS) Case Insensitivity Clarification
Informatively referenced by — RFC 5771: IANA Guidelines for IPv4 Multicast Address Assignments
Informatively referenced by — RFC 5398: Autonomous System (AS) Number Reservation for Documentation Use
Informatively referenced by — RFC 3092: Etymology of "Foo"
Informatively referenced by — RFC 6195: Domain Name System (DNS) IANA Considerations
Informatively referenced by — RFC 9907: Guidelines for Authors and Reviewers of Documents Containing YANG Data Models
Informatively referenced by — RFC 3568: Known Content Network (CN) Request-Routing Mechanisms
Informatively referenced by — RFC 5178: Generic Security Service Application Program Interface (GSS-API) Internationalization and Domain-Based Service Names and Name Type
Informatively referenced by — RFC 7118: The WebSocket Protocol as a Transport for the Session Initiation Protocol (SIP)
Informatively referenced by — RFC 3123: A DNS RR Type for Lists of Address Prefixes (APL RR)
Informatively referenced by — RFC 3675: .sex Considered Dangerous
Informatively referenced by — RFC 6963: A Uniform Resource Name (URN) Namespace for Examples
Informatively referenced by — RFC 7393: Using the Port Control Protocol (PCP) to Update Dynamic DNS
Informatively referenced by — RFC 7977: The WebSocket Protocol as a Transport for the Message Session Relay Protocol (MSRP)
Informatively referenced by — RFC 8023: Report from the Workshop and Prize on Root Causes and Mitigation of Name Collisions