Hello,
This warn is known for some time. It's safe to ignore this warning no matter how many times you see it in your log file, IIRC it's a libevent issue when DNS resolvers are idle. All my exit relays have multiple such lines in the log files constantly.
It's highly important to run your own resolver on localhost 127.0.0.1 such as unbound or bind. Installation is pretty straight forward since you need only a resolver. You will still get this warning even with your own resolver hosted on localhost regardless if you use unbound or bind, it's unrelated to this warning message, but using a local resolver will help privacy of the users using your exit. It's the recommended way to run exit relays.
On 6/19/2016 10:59 PM, pa011 wrote:
Jun 19 20:24:38.000 [warn] eventdns: All nameservers have failed Jun 19 20:24:38.000 [notice] eventdns: Nameserver 8.8.4.4:53 is back up
I do get this in my logs on an exit (Tor 0.2.7.6) several times every hour.
The /etc/resolv.conf contains
# Generated by SolusVM nameserver 8.8.8.8 nameserver 8.8.4.4
Is it really best to set only one DNS like specified here https://trac.torproject.org/projects/tor/ticket/11600 ?
Or are there better working solutions?