Wildcards
Mark_Andrews at isc.org
Mark_Andrews at isc.org
Wed Apr 24 23:26:06 UTC 2002
> Hi,
>
> I was wondering as to what the downsides of having Wildcards would be? I
> have been reading and have found many sources that say it is a bad idea;
> however I'd like to know some more specifics if possible..
>
>
> Thanks..
>
Well many people don't actually understand how wildcards work.
Like the expect adding "* MX 0 mail-server.example.com." will
add a MX record for every name in the zone. It doesn't. It only
add MX records for names that don't exist in the zone.
It also delays the error response to entering a mis-spelled name.
e.g.
Given "* A 1.2.3.4", "wwww.example.com" would cause the server
to attempt the connection only to be told the name is bad rather
than giving immediate feedback. If you were trying to send mail
to user at www.example.com the local mta would accept
user at wwww.example.com rather than returning a error message
immediately. This can then sit in a queue for a long while until
the a delivery attempt succeeds at which time you get the error
message.
In otherwords if you can enumerate the name space it is much better
to do that.
Mark
--
Mark Andrews, Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742 INTERNET: Mark.Andrews at isc.org
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