Wildcard for Reverse Lookups??

Barry Margolin barmar at bbnplanet.com
Thu Jan 20 20:24:41 UTC 2000


In article <9puh4.56$GD6.21597 at ralph.vnet.net>,  <nss at vnet.net> wrote:
>Hi All!
>
>My company has an 'external' DNS server that just lists the bare essentials.
>We only have a few A and PTR records available to the Internet.  So far
>this has been working OK.
>
>There are times when some of our internal clients will go to sites that do
>reverse lookups.  Because we do not have an external PTR record for every IP
>address on our internal network, the reverse lookup fails.  Thus the client is
>unable to complete either the FTP or HTTP download.
>
>The last thing I want to do is to put all 30,000 internal PTR records on the
>external DNS!   Is there a way to configure a 'wildcard' for PTR records?

Yes:

* IN PTR randomhost.yourdomain.com.

However, this probably won't solve your problem.  Those sites that require
PTR records also usually check that you're not spoofing reverse DNS.  So
when the reverse lookup returns randomhost.yourdomain.com, they'll perform
a forward lookup of that name to see if they get the address they started
with.  Unless you have 30,000 A records for randomhost (which probably
wouldn't work anyway) this will fail.

If you upgrade to BIND 8.2 you can use $GENERATE to create A and PTR
records automatically:

$GENERATE 1-255 host-$ A 1.2.3.$

will create A records for host-1 through host-255 pointing to address
1.2.3.1 through 1.2.3.255.

-- 
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.



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