Response Policy Regular Expression Question

[LeBlanc, Daniel James]

Thanks Havard.

Appreciate the candor.  This was my understanding given the articles and documentation that I reviewed.

Dan

-----Original Message-----
From: Havard Eidnes <he at uninett.no> 
Sent: Monday, January 24, 2022 10:13 AM
To: LeBlanc, Daniel James <daniel.leblanc at bellaliant.ca>
Cc: bind-users at lists.isc.org
Subject: [EXT]Re: Response Policy Regular Expression Question

> I am trying to create an NXDOMAIN response-policy for the following 
> example domain:
>
> x.yy.*.*.dns.*
>
> I have reviewed RFC1034 & RFC4592 and many online articles and blog 
> postings, but thus far have not found anything suggesting that this 
> type of match is possible.  Am I expecting too much?
> :)

In a word: yes.

If I'm not terribly mistaken, the DNS response policy code uses normal DNS lookup mechanisms.  What you see sometimes in the DNS is '*' which is a "wildard".  It is not used to form Regular
Expressions(!)  Furthermore, it has the limitation that it can only occur once in a query, and match a single label at the leftmost edge of the looked-up name, and if registered in a zone, its data will be returned if the looked-up name doesn't otherwise exist in the zone (or if it's explicitly queried for).

Regards,

- Håvard
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