Re: Has anyone implemented "double forward DNS"?

From: Ansgar Wiechers <>
Subject: Re: Has anyone implemented "double forward DNS"?

On 2008-08-30 Duncan Simpson wrote:
> Double reverse DNS, which checks the name found using reverse DNS
> matches the IP adrdess enquired about is now common. I was wondering
> wether about has applied the same technique to forward DNS queries
> too.
> The idea here is that a client that finds is
> does not trist this infiormation. Instead it looks up
> and checks for a PTR record saying
> If one is not found then the result is disinformation
> and should not be used.


cobalt@chrome:~ $ host    CNAME CNAME        A
cobalt@chrome:~ $ host        PTR
cobalt@chrome:~ $ host   A
cobalt@chrome:~ $ _

You can have multiple names resolving to the same IP address, but just
one PTR record mapping that address back to a name.

Ansgar Wiechers
"All vulnerabilities deserve a public fear period prior to patches
becoming available."
--Jason Coombs on Bugtraq

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