DNS server on multisite environment?

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Guys,

We have two sites that are connected together and now
we need a DNS solution installed for name resolution
and centralised maintenance.

Everyone should be able to resolve the host names even
if the host lives on the remote site.
If one of the sites goes down than the name resolution
still should work.

But it would be very handy just to edit the DNS file
on a dedicated server each time and the change would
be distributed to the others automatically.
And we also need a fault-tolerant solution if the
remote site and the local primary server goes down,
the name resolution still has to work.

I'm just wondering now how we should plan the DNS
servers to achieve all of these requirements.

Sorry for the confusing explanation...

Thanks in advance!

John