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

["Steve Snyder" <swsnyder@xxxxxxxxxxxxx>]

I see the same thing, and have a working theory: the network connection is saturated, which delays name resolution, causing the log entries.

I run 2 relays on residential ISPs, limiting Tor to about 1/3 of my upload bandwidth.  No problems (nameserver log entries) seen on these relays.

I also run 2 relays on dedicated servers, attempting to fully-utilize a 10Mbps connection on each server.  With the bandwidth configured for 900KB/sec I get a lot of these log entries.  Both of these are running Unbound as a caching DNS server, and neither server is CPU- or memory-constrained.

A couple days ago I changed to the BIND name server as an experiment.  It seems to have helped, but is too early to say for sure.

I've been resisting he reduction of the configured Tor bandwidth, but that will be the next attempt to eliminate the log entries.

-------------------

# bin/tor-dns-fails.sh
Oct 23 DNS failures: 30
Oct 24 DNS failures: 102
Oct 25 DNS failures: 68
Oct 26 DNS failures: 52
Oct 27 DNS failures: 77
Oct 28 DNS failures: 88
Oct 29 DNS failures: 59
Oct 30 DNS failures: 72
Oct 31 DNS failures: 119
Nov 01 DNS failures: 52
Nov 02 DNS failures: 38
Nov 03 DNS failures: 45
Nov 04 DNS failures: 45
Nov 05 DNS failures: 73
Nov 06 DNS failures: 21
Nov 07 DNS failures: 81
Nov 08 DNS failures: 57
Nov 09 DNS failures: 88
Nov 10 DNS failures: 43
Nov 11 DNS failures: 84
Nov 12 DNS failures: 45
Nov 13 DNS failures: 75
Nov 14 DNS failures: 80
Nov 15 DNS failures: 70
Nov 16 DNS failures: 47
Nov 17 DNS failures: 46
Nov 18 DNS failures: 91
Nov 19 DNS failures: 121
Nov 20 DNS failures: 85
Nov 21 DNS failures: 106
Nov 22 DNS failures: 95
Nov 23 DNS failures: 86
Nov 24 DNS failures: 113
Nov 25 DNS failures: 66
Nov 26 DNS failures: 47
Nov 27 DNS failures: 97
Nov 28 DNS failures: 40
Nov 29 DNS failures: 35
Nov 30 DNS failures: 91
Dec 01 DNS failures: 61
Dec 02 DNS failures: 9
Dec 03 DNS failures: 5

-----Original Message-----
From: "Klaus Layer" <klaus.layer@xxxxxx>
Sent: Saturday, December 3, 2011 1:38am
To: tor-relays@xxxxxxxxxxxxxxxxxxxx
Subject: [tor-relays] Logs full of "eventdns: All nameservers have failed"

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Hi,

my logs are full of these messages:

05:54:07 [NOTICE] eventdns: Nameserver 127.0.0.1 is back up
05:54:07 [WARN] eventdns: All nameservers have failed

At first I thought that the DNS of my ISP sucks, so I changed to Google Public 
DNS. But the warnings are still there. 

Google shows some older reports of this warning, where is was supposed to be 
an error in tor. Are there any news on this?

I am wondering if the high bandwidth nodes from torservers and noisebridge 
also show this kind of messages and how they configured their nodes to get rid 
of it. For my node they come up every couple of minutes. Between fail and 
recover is always less than a second.

Best regards,

Klaus


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