large organization nameservers sending icmp packets to dns servers.
don at calis.blacksun.org
Tue Aug 7 18:14:11 UTC 2007
> All things being equal (which they're usually not) you could use the ACK
> response time of the TCP handshake if they've got TCP DNS resolution
> available. Though again most don't for security reasons...
Then most are incredibly stupid.
Several anti DoS utilities force unknown hosts to initiate a query via
TCP in order to be whitelisted. If the host can't perform a TCP query then
they get blacklisted.
In addition, any UDP truncated response needs to be retried via TCP-
blocking it would cause a variety of problems.
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