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What action will those servers take when they receive a request from a non Xtra IP?

I forgot to switch the forwarded on one of my dns servers away from xtra when I changed ISPs and last week (or the previous week?) I couldn't resolve any non-xtra/telecom queries.. I just got request denied (440?) errors. I have since fixed my forwarder entry but I would suggest that the change was already made (or maybe the change was made and it was subsequently rolled back in favour of a public notice) -- Regan