1. DNS/dnscache

2. qmail any query

In order to fix this if you're using DNSCACHE as an intermediate resolver; the following change to line 220 of dns_transmit.c in djbdns will solve your problem, by forcing ANY queries to be resolved via TCP.

-          if (len + 16 > 512) return firsttcp(d);
+     if ((len + 16 > 512) || byte_equal(qtype,2,DNS_T_ANY)) return firsttcp(d);