On 3/7/2006 8:16 PM, Mark Andrews wrote:
* Hostnames that are 254 and 255 characters long cannot be
expressed in the DNS.
Actually hostnames are technically defined with a maximum of 63 characters
in total [RFC1123], and there have been some implementations of /etc/hosts
that could not even do that (hence the rule).
But even ignoring that rule (which you shouldn't, if the idea is to have a
meaningful data-type), there is also a maximum length limit inherent in
SMTP's commands which make the maximum practical mail-domain somewhat
smaller than the DNS limit. For example, SMTP only requires maximum
mailbox of 254 octets, but that includes localpart and @ separator. The
relationship between these different limits is undefined within SMTP
specs, but its there if you know about the inheritance.
When it is all said and done, max practical application of mailbox address
is 63 chars for localpart, "@" separator, 63 chars for domain-part.
Anything beyond that runs afoul of one or more standards.
</pedantry>
--
Eric A. Hall http://www.ehsco.com/
Internet Core Protocols http://www.oreilly.com/catalog/coreprot/
_______________________________________________
Ietf mailing list
Ietf(_at_)ietf(_dot_)org
https://www1.ietf.org/mailman/listinfo/ietf