RFC 4343 · PROPOSED STANDARD · 2006
SAT · 13 JUN 2026
Domain Name System Case Insensitivity Clarification
Overview
RFC 4343, “Domain Name System Case Insensitivity Clarification”, is a Proposed Standard document published in January 2006 by D. Eastlake 3rd. It updates RFC 1034, RFC 1035, RFC 2181. It has since been updated by RFC 5890. The canonical text is published by the RFC Editor.
Abstract
Domain Name System (DNS) names are "case insensitive". This document explains exactly what that means and provides a clear specification of the rules. This clarification updates RFCs 1034, 1035, and 2181. [STANDARDS-TRACK]
What “Proposed Standard” means
An entry-level standards-track specification: stable, peer-reviewed and a solid basis for implementation, though it may still evolve before becoming an Internet Standard.
Read this RFC
The canonical text of RFC 4343 is hosted at rfc-editor.org. Available in TXT,HTML.
Relationships to other RFCs
Other RFCs from 2006
- RFC 4342 Profile for Datagram Congestion Control Protocol Congestion Control ID 3: TCP-Friendly Rate Control
- RFC 4344 The Secure Shell Transport Layer Encryption Modes
- RFC 4341 Profile for Datagram Congestion Control Protocol Congestion Control ID 2: TCP-like Congestion Control
- RFC 4345 Improved Arcfour Modes for the Secure Shell Transport Layer Protocol
- RFC 4340 Datagram Congestion Control Protocol
- RFC 4346 The Transport Layer Security Protocol Version 1.1
- RFC 4339 IPv6 Host Configuration of DNS Server Information Approaches
- RFC 4347 Datagram Transport Layer Security