Re: DNS Mirroring

At 11/4/2000, you wrote:
> > We have a client whose global web site and email are hosted in Hong Kong:
> >
> > Our client would like to be able to set up hosting and email in Europe 
> using
> > the SAME domain name. The idea is that detection will take place to say "if
> > requesting IP is in Europe send it to machine based in Europe else go to
> > Hong Kong".
> >
> > My limited understanding of this makes me think that this is not 
> possible. I
> > can see that it would be possible to have a site such as europe.domain.com,
> > but that all requests for both email and web have to go through one
> > authoratative DNS source (in Hong Kong).
> >
> > Is there such a thing as mirroring in this context?
>
>No. What you can do is ask the user whether they are in Europe, and set
>a cookie appropriately so that you'll know the next time.
>As for email, you can do some forwarding based on the username, but you
>have to have a MX host for the domain name.

Actually, that's not true.  What the original author is asking about is 
called "multi-homing".

A DNS server does a reverse lookup of the IP address making the DNS request 
and based on where its registered, it returns what it believes is the 
closest server to that location.

You can also use multi-homing to prevent overloading of a single server 
when a site is popular.  The DNS server rotates through different server 
lists each time a DNS request is made.

It's not easy to set up, but it can be done.  I don't know of any DNS 
server products for the Windows platform which support multi-homing, but 
there are several available for the Linux platform.

--Dave

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