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Use of Bit 0x20 in DNS Labels to Improve Transaction Identity

Document Type Expired Internet-Draft (individual)
Expired & archived
Authors Paul A. Vixie , David Dagon
Last updated 2008-03-18
RFC stream (None)
Intended RFC status (None)
Stream Stream state (No stream defined)
Consensus boilerplate Unknown
RFC Editor Note (None)
IESG IESG state Expired
Telechat date (None)
Responsible AD (None)
Send notices to (None)

This Internet-Draft is no longer active. A copy of the expired Internet-Draft is available in these formats:


The small (16-bit) size of the DNS transaction ID has made it a frequent target for forgery, with the unhappy result of many cache pollution vulnerabilities demonstrated throughout Internet history. Even with perfectly and unpredictably random transaction ID's, random and birthday attacks are still theoretically feasible. This document describes a method by which an initiator can improve transaction identity using the 0x20 bit in DNS labels.


Paul A. Vixie
David Dagon

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)