reasonable length of FQDN
Mark Andrews
Mark_Andrews at isc.org
Wed Feb 1 21:58:50 UTC 2006
> In article <drphne$cog$1 at sf1.isc.org>,
> Roman Mashak <romez777 at gmail.com> wrote:
>
> > Hello,
> >
> > what may be the reasonable length of fully-quialilfied domain name
> > that can be set up in application? I'd wish this length would cover
> > possible user desires and at the same time wouldn't violate standard.
>
> 255 characters assuming one octet per character.
>
> http://www.ietf.org/rfc/rfc2181.txt
>
> The DNS itself places only one restriction on the particular labels
> that can be used to identify resource records. That one restriction
> relates to the length of the label and the full name. The length of
> any one label is limited to between 1 and 63 octets. A full domain
> name is limited to 255 octets (including the separators).
Well the DNS can only support hostnames up to 253 octets.
Note a hostname does not have a period at the end (RFC 952).
The same limits apply to mail domains in the DNS for the
same reasons.
> --
> Christian Smith
> Dynamic Network Services, Inc.
>
>
--
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742 INTERNET: Mark_Andrews at isc.org
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