Wildcards on A records

[Barry Margolin]

In article <87ajqq$4ul$1 at news.hk.linkage.net>,
Koyo Wong <koyo.wong at hk.china.com> wrote:
>Hi Barry, do you mean wildcard lookup (*.mysubdomain.mydomain.com) is
>supported for any types of records (A, MX, etc.) in any version of BINDs? I
>am uncertain of this.

Yes.  The algorithm is as followed (much simplified -- see RFC 1034 for the
complete details).  When looking for a record of type T for name N, do:

1. Search for the name N exactly.  If it exists, return any records of type
T attached to that name (if there aren't any, the Answer section will be
empty).

2. If N doesn't exist, search for a matching wildcard.  If it exists,
return any records of type T attached to the wildcard record (if there
aren't any, the answer section will be empty).

3. If neither N nor a matching wildcard exist, return an answer with
status=NXDOMAIN.

As I said, this is a simplified summary of the algorithm (it doesn't deal
with delegated subdomains and CNAME records, for instance).  But as far as
knowing whether a wildcard will work, it should be adequate.  The RFC
describing this algorithm is 13 years old, and BIND has always implemented
this, as far as I know.

What makes you uncertain -- did you try it and it didn't work?

-- 
Barry Margolin, barmar at bbnplanet.com
GTE Internetworking, Powered by BBN, Burlington, MA
*** DON'T SEND TECHNICAL QUESTIONS DIRECTLY TO ME, post them to newsgroups.
Please DON'T copy followups to me -- I'll assume it wasn't posted to the group.