I've recently switched out a failed router... and, a while later, I discovered a lot (at least an order or magnitude more than the number of queries) of errors reported in /var/log/syslog - of the form:
Mar 18 19:53:20 kenneth named: DNS format error from 18.104.22.168#53 resolving ./NS: non-improving referral Mar 18 19:53:20 kenneth named: error (FORMERR) resolving './NS/IN': 22.214.171.124#53
It might be relevant that I've got the following in bind.conf:
dnssec-enable no; dnssec-validation no;
Is this likely an issue with the new router corrupting UDP datagrams, or something else? The new router is an (inexpensive) Netgear WNR854T - it has the latest firmware applied.
Can anyone suggest how best to diagnose this fault if it's not obvious from the above?
-- Additional details -- This is a typical response from dig for an address I'm sure should resolve.
$ dig A barclays.co.uk ~ ; <<>> DiG 9.8.1-P1 <<>> A barclays.co.uk ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 22161 ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;barclays.co.uk. IN A ;; Query time: 84 msec ;; SERVER: 127.0.0.1#53(127.0.0.1) ;; WHEN: Wed Mar 20 23:08:40 2013 ;; MSG SIZE rcvd: 32 $