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Inconsistency? (was: Anti-Spoofing Technology)

2005-04-17 15:20:04
I have been reviewing some of the RFCs you have so kindly recommended.


I have found what appears to be a major inconsistency between RFC2821 and


In RFC2821, a clear definition of the structure of a domain name is
provided.  In this definition, the length of a domain name may not exceed
255 characters, and consists of one (1) or more "labels", each separated
from the other by a period (".").  The length of each label may not exceed
63 characters.  Each label must begin with an alphabetic character
(case-insensitive) and must terminate with an alphabetic character (again,
case-insensitive) or with a decimal digit.  Characters internal to a label
may be alphabetic (again, case-insensitive), decimal digit, or hyphen ("-").


In RFC2822, the definition is more obscure, with the domain name character
set consisting of a much broader subset of ASCII.  Of particular concern is
the fact that in this RFC, ASCII character which have special meaning such
as "@" appear to be valid within a domain name.


Based upon the problems in RFC2822, I must conclude that the domain name
specification provided therein is incorrect.


Does RFC2821 correctly reflect the syntactic requirements for domain names,
or is it too incorrect, and there exists some other RFC which specifically
addresses the issue?


John P Baker

Software Engineer

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