Wildcards

[Mark_Andrews at isc.org]

> 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