reasonable length of FQDN

Stephane Bortzmeyer bortzmeyer at
Wed Feb 1 09:07:50 UTC 2006

On Wed, Feb 01, 2006 at 04:50:28PM +1100,
 Mark Andrews <Mark_Andrews at> 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 :-)

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 (68
characters) and
works :-)

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