Not sure if this kind of thing is what you're looking for, but Jeff Atwood posted somewhat recently about their change of DNS Provider for StackOverflow (here: http://blog.stackoverflow.com/2009/09/new-dns-provider/) because of DNS instability and response times. Might be a good jump-off point for great reading about speeding up your DNS.
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Not sure if this kind of thing is what you're looking for, but Jeff Atwood posted somewhat recently about their change of DNS Provider for StackOverflow (here: http://blog.stackoverflow.com/2009/09/new-dns-provider/) because of DNS instability and response times. Might be a good jump-off point for great reading about speeding up your DNS.