reasonable length of FQDN

Mark Andrews Mark_Andrews at isc.org
Wed Feb 1 12:55:56 UTC 2006


> On Wed, Feb 01, 2006 at 04:50:28PM +1100,
>  Mark Andrews <Mark_Andrews at isc.org> wrote 
>  a message of 25 lines which said:
> 
> > To simplify implementations, the total number of octets that
> > represent a domain name (i.e., the sum of all label octets and label
> > lengths) is limited to 255.
> 
> If the OP said "reasonable" and not "legal", I believe it is because
> he have already read the RFC and wanted a more operational answer :-)

	There are plenty of real world hostnames that are 253 characters
	long.  People like to have fun. :-)
 
> For instance, mtr, by default, truncates the FQDN at the first 33
> characters for display. This is probably the sort of things the OP had
> in mind.
> 
> Another example is that the longest domain name in ".fr", far from the
> theoretical limit (but it hits the limit for a label), is 
> bolognaise-cannes-moulinets-soies-culdecanard-mouches-flotteurs.fr (68
> characters) and
> www.bolognaise-cannes-moulinets-soies-culdecanard-mouches-flotteurs.fr
> works :-)

--
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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