[dns-operations] Zone cut on _tcp.example.ca

Robert Edmonds edmonds at mycre.ws
Wed Feb 10 00:24:03 UTC 2016

Jacques Latour wrote:
> One of our d-zone (secondary dns service) customers wants to a zone that looks like this:  _tcp.example.ca
> My initial gut feeling was "no", LDH, not a valid label/domain name, but Roy said maybe, RFC2181 section 11. "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.".

Fortunately the LDH rule doesn't apply to zone names, otherwise "."
would be out of luck :-)

I've run into secondary DNS service providers that have a special rule
against zone names that look like this: "www.example.com".  Apparently
it causes too much of a support burden when customers meant to configure
"example.com" instead.

Robert Edmonds

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