[dns-operations] Shameless plug for our Zonecheck software (Was: af.mil DNS issue
jabley at ca.afilias.info
Sun Jul 2 02:55:20 UTC 2006
On 1-Jul-2006, at 13:13, John Payne wrote:
> "Just in case" I'd rather not have an unnecessary DoS vector open
> on my servers if I don't need it.... and taking the experience of a
> company that does a LOT of DNS hits, anyone only doing TCP is in a
> extremely insignificant minority.
Cool. I hadn't actually heard of anybody blocking 53/tcp on purpose,
with full knowledge of the implications before. I have some questions!
Do you log the 53/tcp attempts that you refuse?
Is there a discernible pattern between the queries you see using 53/
udp and those using 53/tcp? Do you see the same client try tcp after
just previously using udp, for example?
Has the DNS server you're using been designed/modified to never
return replies with the TC bit set?
Do you inspect your cusotmers' zones to ensure that no response is
possible that might exceed 512 bytes for a client that doesn't
support EDNS0? Or do you assume everybody supports EDNS0?
Has any customer complained that your DNS service doesn't fully
implement the transport requirements of RFC 1035?
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