If folks from xtube.com/ultradns/dynect are on the list, it appears that there’s a discrepancy in the xtube.com zone being served by the some auths. At least one of the CNAMEs required for resolution is missing from the zone being served by at least some ultra instances. No idea where the breakdown is, but we’ve got customers telling the world that we’re blocking access to porn. I’ll also note that the SOA ttl and ncache are on the large side, so we’re caching those NXDOMAINs for quite a while. Flushing is just playing whack-a-mole at the moment. Also, if folks from any large auths want to provide me with contact info, we’ll happily reach out to you privately/directly should something similar occur in the future . Mark Comcast TPX Core Network Services