[tor-relays] Nameservers fail and come back at the same time?

[Tim Wilson-Brown - teor]

> On 1 Feb 2016, at 06:33, SuperSluether <supersluether at gmail.com> wrote:
> 
> My exit node's consensus weight just jumped from 20 to 1750 overnight. When I checked to see how things were going, my log file is full of nameserver problems, happening every couple of minutes:
> 
> Jan 31 14:12:40.000 [warn] eventdns: All nameservers have failed
> Jan 31 14:12:40.000 [notice] eventdns: Nameserver 8.8.4.4:53 is back up
> Jan 31 14:18:35.000 [warn] eventdns: All nameservers have failed
> Jan 31 14:18:35.000 [notice] eventdns: Nameserver 8.8.4.4:53 is back up
> Jan 31 14:20:53.000 [warn] eventdns: All nameservers have failed
> Jan 31 14:20:53.000 [notice] eventdns: Nameserver 8.8.4.4:53 is back up
> Jan 31 14:20:59.000 [warn] eventdns: All nameservers have failed
> Jan 31 14:20:59.000 [notice] eventdns: Nameserver 8.8.4.4:53 is back up
> 
> But the "All nameservers have failed" and "Nameserver xxx is back up" messages happen in pairs at the exact same time. What's going on here, and is there a way to fix this? My VPS has 2 nameservers listed for it, should I be using those?

The times in tor logs are anonymised by rounding to the nearest second. So these entries are close together, but not necessarily at the same time.

How many DNS servers do you have configured?
(It looks like it's only one. That's quite a fragile configuration.)
If it fails a request by chance, but the next request succeeds, this is the pattern of messages you'll see.

Try adding a local caching resolver as the first listed name server.

You might want to add your VPS DNS servers, and Google's other server to the end of the list, too.
(A benefit of using local DNS servers is that fewer networks see your DNS requests.
A drawback is that your VPS company then sees your DNS requests and your traffic, but they could do this anyway.)

Tim

Tim Wilson-Brown (teor)

teor2345 at gmail dot com
PGP 968F094B

teor at blah dot im
OTR CAD08081 9755866D 89E2A06F E3558B7F B5A9D14F

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