Re: [Asrg] What are the IPs that sends mail for a domain?

David Wilson <> Fri, 19 June 2009 11:14 UTC

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From: David Wilson <>
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Date: Fri, 19 Jun 2009 12:14:20 +0100
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Subject: Re: [Asrg] What are the IPs that sends mail for a domain?
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On Fri, 2009-06-19 at 12:54 +0200, Alessandro Vesely wrote:
> > The FQDN for a host is the host's FQDN.  As we've all noted, there's
> > lots of heuristics to guess domain names, none of which work.
> What about the other way around: given a domain and an IP address, can
> we say whether the IP address "is a member of" the domain?

I would ask: what do you mean by 'domain' in this context?

(The term domain is probably one of the most over-used terms.)

In the context of email addresses, the domain is the part of the address
to the right of the '@'.

I'm not sure if there is a definition for 'domain' as it applies to
hosts and their domain names (fully or partly qualified). There is a
local (to a resolver) definition for searching which can convert a PQDN
to a FQDN, but that is not global data.

There is, of course, the zone in which the FQDN is defined for use in
the DNS.