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DrJohn 13th October 2011 18:50

Dns & uribl
This is Perfect Server Ubuntu 10.04. I recently changed DNS forwarders from my ISP-provided to a pair of the fastest (from here) public DNS sites: SpeakEasy and Google Public DNS. The ISP sites were about 5x slower and were returning advertising material for non-existent domains.

In /etc/bind/named.conf.options:

forwarders {
                // Google Public DNS

I've always seen a number of DNS errors in the logs, like these from the ISP DNS servers:

DNS format error from resolving invalid response: 1 Time(s)
error (FORMERR) resolving '': 17 Time(s)
error (network unreachable) resolving '': 2001:7b8:3:1f:0:2:53:2#53: 1 Time(s)
error (unexpected RCODE REFUSED) resolving '':
success resolving '' (in ''?) after disabling EDNS: 1 Time(s)

but the number is small (< 50 per day) and there seems to be no impact.

After changing the DNS servers, I see a couple of hundred errors related to URIBL DNS queries (out of a 10.04 VM running ISPConfig 2.2.40 / SA) like these (many different domains overall):

error (unexpected RCODE REFUSED) resolving '': 1 Time(s)
All of these were returned from the Google Public DNS server.
In addition, I see about the same number of these and similar:

error (network unreachable) resolving 'C.ROOT-SERVERS.NET/AAAA/IN': 2001:500:2f::f#53: 1 Time(s)
error (network unreachable) resolving '': 2001:7fd::1#53: 1 Time(s)
error (network unreachable) resolving '': 2001:503:c27::2:30#53: 1 Time(s)

I'd like to clear this up on the server. Is this a symptom of 1) a problem with the local Bind installation; 2) a problem with SA / URIBL; 3) a problem with the public DNS servers; 4) not a problem other than syslog inflation?

Thanks !

DrJohn 15th October 2011 19:13

Apparently this is a problem with the Google Public DNS. I removed it from the list of forwarders and poof! no more such log entries.

-- John

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