Re: [exim] Tricky DNS servers [OT]

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Author: Jonas Eckerman
Date:  
To: exim-users
Subject: Re: [exim] Tricky DNS servers [OT]
On 2012-05-18 23:59, Marc Perkel wrote:

> Here's a possible example. There are servers out there that return
> country codes of IP addresses. But what about a country code for a host
> name? You would have to do an IP lookup on the host and then use the IP
> to get a country code.


I don't see this as a problem, since it actually spreads the load of the
loookup to different DNS servers and proxies and the client.

Considering lookups done by an MTA or anti-spam system, the system is
likely to lookup the IP address of any "interresting" hostname anyway so
the result of that lookup should be in the cache allready except for the
first lookup.

> So - is there source code for something like this


Obviously, yes. There are open source DNS servers that can do recursion
when answering DNS queries. The source code for such a server has the
building blocks you need for your idea.

> or a DNS server with a scripting language?


What about a DNS server written in a scripting language?

<http://search.cpan.org/~olaf/Net-DNS-0.68/lib/Net/DNS/Nameserver.pm>
<http://search.cpan.org/~bbb/Net-DNSServer-0.11/lib/Net/DNSServer.pm>

There's likely to be at least one name server written in Python as well.

Regards
/Jonas
--
Jonas Eckerman
http://www.truls.org/