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Intermittent DNS server failure

wynnmc
Dabbler
Posts: 15
Registered: 03-04-2008

Intermittent DNS server failure

Hello
From about midday I've been getting intermittent failures of the DNS server to return an address.
Sometimes repeated attempts to load a page (or, better, to ping the site) resolves the problem.
I've rebooted my router two or three times so I don't think it is that and it reports that it has 212.159.6.9 as the primary server and  212.159.6.10 as rhe secondary.
This has happened in the past but has cleared after a time or by rebooting the router.
The sites it has had trouble with are webmail.spamcop.net, duckduckgo.com, and gentoo.org -- is there a problem with DNS to America?
Chris
12 REPLIES
pwatson
Rising Star
Posts: 2,468
Thanks: 8
Fixes: 1
Registered: 26-11-2012

Re: Intermittent DNS server failure

Possibly the same issue as being discussed towards the end of the 'DNS seems high' thread?
http://community.plus.net/forum/index.php/topic,118268.msg1030743.html#msg1030743
Community Veteran
Posts: 5,472
Thanks: 291
Fixes: 4
Registered: 11-08-2007

Re: Intermittent DNS server failure

Try changing your DNS settings from Plusnet to one from OpenDNS (e.g. - 208.67.220.220) and another from Google (e.g. - 8.8.8.8 ).
This will eliminate whether you really have a DNS connectivity problem, or whether you have a router problem or wireless issue.
Unfortunately if you are using Windows, it often reports a DNS fault when what has really happened is a general loss of connection.

wynnmc
Dabbler
Posts: 15
Registered: 03-04-2008

Re: Intermittent DNS server failure

@pwatson: I was just reading the start of that thread  Smiley ... I hadn't associated slow DNS with (apparent) failure -- Firefox (for instance) tried for several seconds before giving up.
@purleigh: thanks -- my router seems to have gone catatonic when asked to change its DNS  Sad -- it may be some time before I can post results.
Thank you both for your swift replies  Smiley
Chris
Community Veteran
Posts: 2,265
Thanks: 102
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Registered: 18-02-2013

Re: Intermittent DNS server failure

What router do you have ? If it's a tg582n then this may help http://npr.me.uk/changedns.html
Community Veteran
Posts: 5,472
Thanks: 291
Fixes: 4
Registered: 11-08-2007

Re: Intermittent DNS server failure

If the router is doing odd things, I wonder if it needs clearing back to factory defaults, and then setting a fresh configuration.
You might also want to consider ensuring that you have the latest firmware installed as well.
wynnmc
Dabbler
Posts: 15
Registered: 03-04-2008

Re: Intermittent DNS server failure

My router is a Belkin F5D8635-4 v1, I reset it to factory defaults not long ago and set it up again. When I get these problems I assume its OS has got in a twist and that rebooting it will sort it out again. There is advice from time to time about unplugging it for an hour to get a new connection -- sometimes I do that.
Here are some answers (thanks to ejs on the other thread for dig)
run-dig.sh 8.8.8.8
; <<>> DiG 9.9.3-P2 <<>> @8.8.8.8 webmail.spamcop.net
;; Query time: 45 msec
;; connection timed out; no servers could be reached
;; Query time: 38 msec
;; Query time: 38 msec
;; Query time: 36 msec
;; Query time: 38 msec
;; Query time: 40 msec
;; Query time: 44 msec
;; Query time: 37 msec
;; Query time: 37 msec
run-dig.sh 208.67.220.220
; <<>> DiG 9.9.3-P2 <<>> @208.67.220.220 webmail.spamcop.net
;; Query time: 41 msec
;; Query time: 31 msec
;; Query time: 31 msec
;; connection timed out; no servers could be reached
;; Query time: 42 msec
;; connection timed out; no servers could be reached
;; Query time: 39 msec
;; Query time: 32 msec
;; connection timed out; no servers could be reached
;; Query time: 40 msec
run-dig.sh 212.159.6.9
; <<>> DiG 9.9.3-P2 <<>> @212.159.6.9 webmail.spamcop.net
;; Query time: 39 msec
;; Query time: 32 msec
;; Query time: 32 msec
;; connection timed out; no servers could be reached
;; Query time: 41 msec
;; Query time: 33 msec
;; Query time: 31 msec
;; Query time: 31 msec
;; Query time: 32 msec
;; Query time: 31 msec
run-dig.sh 212.159.6.10
; <<>> DiG 9.9.3-P2 <<>> @212.159.6.10 webmail.spamcop.net
;; Query time: 39 msec
;; Query time: 30 msec
;; Query time: 33 msec
;; Query time: 33 msec
;; connection timed out; no servers could be reached
;; Query time: 39 msec
;; Query time: 32 msec
;; Query time: 34 msec
;; Query time: 31 msec
;; Query time: 35 msec
Curious, no?
Chris
PeeGee
Aspiring Pro
Posts: 1,081
Thanks: 45
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Registered: 05-04-2009

Re: Intermittent DNS server failure

Quote from: purleigh
Google (e.g. - 8.8.8.Cool.

Huh Time to start inserting a space before the ")", methinks Roll eyes  ->  8.8.8.8 ) Shocked
Plusnet Fibre (Sep 2014), Essentials (Feb 2013); ADSL (Apr 2009); Customer since Jan 2004 (on 28kb dial-up)
Using a TP-Link TD-W9980 modem-router.
Community Veteran
Posts: 5,472
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Registered: 11-08-2007

Re: Intermittent DNS server failure

Embarrassed hadn't spotted that,  fixed now.
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Registered: 10-06-2010

Re: Intermittent DNS server failure

I had a ping command running while doing the DNS lookups, to demonstrate that there wasn't other packet loss occurring (due to my dreadful line) while the DNS lookups were failing.
But since you also saw failures with Google DNS and OpenDNS, then you probably have a more general problem.
wynnmc
Dabbler
Posts: 15
Registered: 03-04-2008

Re: Intermittent DNS server failure

@ejs Aah, pings! Not having any experience of this, are the packet losses to both DNS servers what you'd expect?
Chris
$ ping 212.159.6.9
PING 212.159.6.9 (212.159.6.9) 56(84) bytes of data.
64 bytes from 212.159.6.9: icmp_seq=1 ttl=250 time=39.4 ms
64 bytes from 212.159.6.9: icmp_seq=2 ttl=250 time=40.8 ms
64 bytes from 212.159.6.9: icmp_seq=3 ttl=250 time=39.2 ms
64 bytes from 212.159.6.9: icmp_seq=4 ttl=250 time=41.6 ms
64 bytes from 212.159.6.9: icmp_seq=5 ttl=250 time=39.6 ms
64 bytes from 212.159.6.9: icmp_seq=6 ttl=250 time=39.3 ms
64 bytes from 212.159.6.9: icmp_seq=7 ttl=250 time=39.7 ms
64 bytes from 212.159.6.9: icmp_seq=8 ttl=250 time=42.1 ms
64 bytes from 212.159.6.9: icmp_seq=9 ttl=250 time=39.0 ms
64 bytes from 212.159.6.9: icmp_seq=10 ttl=250 time=39.5 ms
^C
--- 212.159.6.9 ping statistics ---
10 packets transmitted, 10 received, 0% packet loss, time 9013ms
rtt min/avg/max/mdev = 39.014/40.067/42.169/1.079 ms
ping 212.159.6.10
PING 212.159.6.10 (212.159.6.10) 56(84) bytes of data.
64 bytes from 212.159.6.10: icmp_seq=1 ttl=250 time=40.5 ms
64 bytes from 212.159.6.10: icmp_seq=2 ttl=250 time=39.6 ms
64 bytes from 212.159.6.10: icmp_seq=3 ttl=250 time=38.7 ms
64 bytes from 212.159.6.10: icmp_seq=5 ttl=250 time=41.0 ms
64 bytes from 212.159.6.10: icmp_seq=6 ttl=250 time=39.0 ms
64 bytes from 212.159.6.10: icmp_seq=7 ttl=250 time=43.3 ms
64 bytes from 212.159.6.10: icmp_seq=8 ttl=250 time=39.0 ms
64 bytes from 212.159.6.10: icmp_seq=9 ttl=250 time=31.3 ms
64 bytes from 212.159.6.10: icmp_seq=10 ttl=250 time=42.0 ms
64 bytes from 212.159.6.10: icmp_seq=11 ttl=250 time=44.4 ms
^C
--- 212.159.6.10 ping statistics ---
11 packets transmitted, 10 received, 9% packet loss, time 10012ms
rtt min/avg/max/mdev = 31.360/39.929/44.431/3.388 ms
$ ping -c16 212.159.6.9
PING 212.159.6.9 (212.159.6.9) 56(84) bytes of data.
64 bytes from 212.159.6.9: icmp_seq=1 ttl=250 time=42.6 ms
64 bytes from 212.159.6.9: icmp_seq=2 ttl=250 time=40.1 ms
64 bytes from 212.159.6.9: icmp_seq=3 ttl=250 time=42.2 ms
64 bytes from 212.159.6.9: icmp_seq=4 ttl=250 time=39.8 ms
64 bytes from 212.159.6.9: icmp_seq=5 ttl=250 time=39.7 ms
64 bytes from 212.159.6.9: icmp_seq=6 ttl=250 time=31.3 ms
64 bytes from 212.159.6.9: icmp_seq=8 ttl=250 time=39.7 ms
64 bytes from 212.159.6.9: icmp_seq=9 ttl=250 time=39.8 ms
64 bytes from 212.159.6.9: icmp_seq=10 ttl=250 time=43.4 ms
64 bytes from 212.159.6.9: icmp_seq=11 ttl=250 time=40.6 ms
64 bytes from 212.159.6.9: icmp_seq=12 ttl=250 time=40.3 ms
64 bytes from 212.159.6.9: icmp_seq=13 ttl=250 time=39.5 ms
64 bytes from 212.159.6.9: icmp_seq=14 ttl=250 time=40.7 ms
64 bytes from 212.159.6.9: icmp_seq=15 ttl=250 time=40.4 ms
--- 212.159.6.9 ping statistics ---
16 packets transmitted, 14 received, 12% packet loss, time 15021ms
rtt min/avg/max/mdev = 31.307/40.043/43.409/2.687 ms
$ ping -c16 212.159.6.10
PING 212.159.6.10 (212.159.6.10) 56(84) bytes of data.
64 bytes from 212.159.6.10: icmp_seq=1 ttl=250 time=40.7 ms
64 bytes from 212.159.6.10: icmp_seq=2 ttl=250 time=41.6 ms
64 bytes from 212.159.6.10: icmp_seq=3 ttl=250 time=40.0 ms
64 bytes from 212.159.6.10: icmp_seq=4 ttl=250 time=40.0 ms
64 bytes from 212.159.6.10: icmp_seq=5 ttl=250 time=39.5 ms
64 bytes from 212.159.6.10: icmp_seq=6 ttl=250 time=41.5 ms
64 bytes from 212.159.6.10: icmp_seq=7 ttl=250 time=40.0 ms
64 bytes from 212.159.6.10: icmp_seq=8 ttl=250 time=46.7 ms
64 bytes from 212.159.6.10: icmp_seq=9 ttl=250 time=39.7 ms
64 bytes from 212.159.6.10: icmp_seq=10 ttl=250 time=39.9 ms
64 bytes from 212.159.6.10: icmp_seq=11 ttl=250 time=39.9 ms
64 bytes from 212.159.6.10: icmp_seq=12 ttl=250 time=39.4 ms
64 bytes from 212.159.6.10: icmp_seq=13 ttl=250 time=39.5 ms
64 bytes from 212.159.6.10: icmp_seq=15 ttl=250 time=40.6 ms
64 bytes from 212.159.6.10: icmp_seq=16 ttl=250 time=39.5 ms
--- 212.159.6.10 ping statistics ---
16 packets transmitted, 15 received, 6% packet loss, time 15019ms
rtt min/avg/max/mdev = 39.478/40.613/46.721/1.759 ms
pwatson
Rising Star
Posts: 2,468
Thanks: 8
Fixes: 1
Registered: 26-11-2012

Re: Intermittent DNS server failure

I think you're confusing the DNS lookup issues with problems caused by general packet loss.  Try pinging 8.8.8.8, www.bbc.co.uk or other sites rather than Plusnet's DNS servers
wynnmc
Dabbler
Posts: 15
Registered: 03-04-2008

Re: Intermittent DNS server failure

Thanks -- if I knew enough about it I would probably agree with you. Huh