Wildcard Q/A

AF af.at.work at gmail.com
Wed Mar 21 19:12:38 UTC 2007

On Mar 21, 1:54 pm, Chris Buxton <cbux... at menandmice.com> wrote:
> A wildcard is a special node in the namespace tree that is used as a
> template to answer queries about its nonexistent siblings. (It also
> covers descendants of non-existent siblings.) Any query for such a
> nonexistent node is answered based on the template provided by the
> wildcard node.
> You should not have a wildcard on the right side of a CNAME record.
> Instead, point the CNAME record to a normal name; that name might be
> a nonexistent name that is covered by the other wildcard. What you
> have may work with some resolving name servers, but I don't think it
> is correct according to the RFCs.
> Example:
> *.foo.example.    CNAMEwww.bar.example.
> *.bar.example.    A
> Otherwise, there's nothing wrong with using wildcards they way you
> currently do. Just be aware that, for example, if you create an MX
> record with a particular name, the wildcard won't be used to
> synthesize an A record for that same name in response to a query,
> because that node will then exist - even though it doesn't own an A
> record.
> Example:
> *.bar.example.    A
> sub.bar.example.  MX    10  mail.bar.example.
> Query: sub.bar.example. IN A
> Answer: "no data" negative response (the node exists but does not own
> that record type)
> Hope this helps.
> Chris Buxton
> Men & Mice
> On Mar 21, 2007, at 6:33 AM, AF wrote:
> > I have a wildcard A record setup and pointed to my web server.. for
> > example:
> > *.bar.com. IN A
> > The web site on this server responds to any request and builds the
> > pages based on their URL (foo.bar.com, me.bar.com, etc.)
> > I can also setup CNAMEs to do the same.. for example:
> > *.foo.com. IN CNAME *.bar.com.
> > This gives different pages & URLs too (abc.foo.com, def.foo.com, etc.)
> > Is there a preferred way to manage that first wildcard? Why should I
> > *not* do this? I have read mixed reviews about its use. Really, could
> > I just have a regular A record (www.bar.com. IN A and then
> > have the wildcard CNAME pointed to it? Same end result?
> > Thanks All.

Thanks for the quick reply Chris.

I am not too sure what you mean by: "You should not have a wildcard on
the ***right side*** of a CNAME record."

It would be better to use a wildcard CNAME record pointed to an A

For example:
*.foo.com. IN CNAME a.abc.com.
*.bar.com. IN CNAME a.abc.com.
a.abc.com. IN A

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