[tor-relays] Logs full of "eventdns: All nameservers have failed"

[Steve Snyder]

On Saturday, December 10, 2011 5:58am, "Klaus Layer" <klaus.layer at gmx.de> said:
>> Could you clarify the configuration?  Is Tor doing DNS over the GigE or
>> to localhost?
>>
>> -andy
> Yes I have configure a local caching DNS server. cat /etc/resolve.conf shows
> nameserver 127.0.0.1. So I assume TOR resolves via the local configured DNS. I
> verified with nslookup. DNS requests indeed go through the 127.0.0.1:53.

Yes, I also have a local caching nameserver, pointed to by the "nameserver 127.0.0.1" entry in /etc/resolve.conf.  Also, it seems that Tor/libevent is smart enough to filter out duplicate DNS servers as 3 copies of "nameserver 127.0.0.1" doesn't give you more retries on the same server.

On a semi-related topic, I can now say the using BIND v9.7 greatly reduces the number of these Tor entries relative to using Unbound v1.4.13.  This is true with Tor 0.2.2.34 on the low (Intel Atom) and high (Xeon 56xx) ends of the CPU spectrum.