RPZ zone name label length limit

Tony Finch dot at dotat.at
Thu Jun 29 18:14:43 UTC 2017

Jim Yang <zy33 at cornell.edu> wrote:
> Thank you for your reply. When you mention “In presentation format some characters
>    have to be \escaped which can make the name up to four times
>    longer.”, where can I find the reference (which RFC)?


> If I want to check if the following name is legal or not, how many
> characters should I check for each label/section/part of the name?


> (skip some labels).information.uzmzudseodc2fjpyi6mjcxndiymtuzmzufazdseyi6swh58fmodc2fjqxoc2fjp.(skip some labels)

Amusingly when I was trying this to see how long it is I found a bug in
iOS dig :-)

$ dig +noall +comment information.uzmzudseodc2fjpyi6mjcxndiymtuzmzufazdseyi6swh58fmodc2fjqxoc2fjp.com
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 36667
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0
$ dig +noall +comment information.uzmzudseodc2fjpyi6mjcxndiymtuzmzufazdseyi6swh58fmodc2fjqxoc2fjpx.com
dig: 'information.uzmzudseodc2fjpyi6mjcxndiymtuzmzufazdseyi6swh58fmodc2fjqxoc2fjpx.com' is not a legal name (label too long)

f.anthony.n.finch  <dot at dotat.at>  http://dotat.at/  -  I xn--zr8h punycode
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