North American Network Operators Group|
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Re: Anycast 101
On Thu, 16 Dec 2004 17:18:12 PST, Crist Clark said: > Into a UDP response. A resolver will recieve the first 512 bytes of the > truncated response and may then use TCP to get the complete response... > unless there is a firewall blocking 53/tcp in the way. But how often > does that happpen? You're new here, aren't you? ;) It happens *all* *the* *time* (probably just as often as sites that block all ICMP including 'frag needed' and wonder why PMTU Discovery breaks and connections hang). The *real* operational problem is that almost 100% of the time that there's a firewall blocking 53/tcp, the person running the firewall is (a) unaware that it's blocking it and (b) doesn't even realize that DNS *can* use TCP.... Quite often, there's even a "(c) they don't even know they have a firewall" just to make things really interesting.