Mailing List Archive

flaky / sparatic dns
i'm not sure when it started, but my dns is officially flakey. sometimes
sites just won't resolve, and others, it'll take a very long time. my first
thought was of course: gibbled dns server(s). but no one else in the office
is having the same problem.

so then i tried a few simple tests:

(2004-10-05 12:13:51) $ host forums.gentoo.org
forums.gentoo.org has address 140.211.166.164
(2004-10-05 12:13:57) $ host forums.gentoo.org
forums.gentoo.org has address 140.211.166.164
(2004-10-05 12:13:57) $

the first request took 6 seconds (short compared to some others) but the
second not even a second. but this isn't the big problem. the delay is most
noticeable when using a program like konqueror to retrieve a page. it
literally can take about 30seconds.

so wondering what was going on, i ran ngrep. it took 17seconds to decide
www.google.ca didn't exist, and after a refresh, another 10 seconds to load
the page (with a dead image). here's what ngrep said:

#
U 192.168.3.232:32966 -> 192.168.2.4:53
.............www.google.ca.....
#
U 192.168.3.232:32967 -> 66.48.69.3:53
.............www.google.ca.....
#
U 192.168.3.232:32967 -> 192.168.2.4:53
.............www.google.ca.....
#
U 192.168.2.4:53 -> 192.168.3.232:32966
.............www.google.ca............./=...www.google.com..
+.......*...www.google.akadns.net..G.......&....'..G.......&....'c.G.......&....'h
#
U 192.168.3.232:32968 -> 66.48.69.3:53
.............www.google.ca.....
#
U 192.168.3.232:32968 -> 192.168.2.4:53
.............www.google.ca.nodes.net.ad-flow.com.....
#
U 192.168.2.4:53 -> 192.168.3.232:32967
.............www.google.ca............./8...www.google.com..+.......
%...www.google.akadns.net..G.......!....'h.G.......!....'..G.......!....'c
#
U 192.168.3.232:32969 -> 66.48.69.3:53
.............www.google.ca.nodes.net.ad-flow.com.....
#
U 192.168.3.232:32969 -> 192.168.2.4:53
.............www.google.ca.nodes.net.ad-flow.com.....
#
U 192.168.2.4:53 -> 192.168.3.232:32968
.............www.google.ca.nodes.net.ad-flow.com......$......Q....$.DNS.
$wt%F..............Q.
#
U 192.168.3.232:32970 -> 66.48.69.3:53
.............www.google.ca.nodes.net.ad-flow.com.....
#
U 192.168.3.232:32970 -> 192.168.2.4:53
.............www.google.ca.....
#
U 192.168.2.4:53 -> 192.168.3.232:32969
.............www.google.ca.nodes.net.ad-flow.com......$......Q....$.DNS.
$wt%F..............Q.
#
U 192.168.3.232:32971 -> 66.48.69.3:53
.............www.google.ca.....
#
U 192.168.3.232:32971 -> 192.168.2.4:53
.............www.google.ca.....
#
U 192.168.2.4:53 -> 192.168.3.232:32970
.............www.google.ca............./)...www.google.com..
+...........www.google.akadns.net.
#
U 192.168.3.232:32972 -> 66.48.69.3:53
.............www.google.ca.....
#
U 192.168.3.232:32972 -> 192.168.2.4:53
.............www.google.ca.nodes.net.ad-flow.com.....
#
U 192.168.2.4:53 -> 192.168.3.232:32972
.............www.google.ca.nodes.net.ad-flow.com......$......Qq...$.dns.
$wt%F...............{
#
U 192.168.2.4:53 -> 192.168.3.232:32971
.............www.google.ca............./$...www.google.com..
+...........www.google.akadns.net.
#
U 192.168.3.232:32972 -> 192.168.2.4:53
5............www.google.ca.....
#
U 192.168.2.4:53 -> 192.168.3.232:32972
5............www.google.ca............./....www.google.com..
+...........www.google.akadns.net..G............'..G............'c.G............'h
#
U 192.168.3.232:32972 -> 192.168.2.4:53
.............www.google.ca.....
#
U 192.168.3.232:32973 -> 66.48.69.3:53
.............www.google.ca.....
#
U 192.168.3.232:32973 -> 192.168.2.4:53
.............www.google.ca.....
#
U 192.168.2.4:53 -> 192.168.3.232:32972
.............www.google.ca............./....www.google.com..
+...........www.google.akadns.net.
#
U 192.168.3.232:32974 -> 66.48.69.3:53
.............www.google.ca.....
#
U 192.168.3.232:32974 -> 192.168.2.4:53
.............www.google.ca.nodes.net.ad-flow.com.....
#
U 192.168.2.4:53 -> 192.168.3.232:32974
.............www.google.ca.nodes.net.ad-flow.com......$......Qc...$.dns.
$wt%F...............m
#
U 192.168.3.232:32974 -> 192.168.2.4:53
.?...........www.google.ca.....
#
U 192.168.2.4:53 -> 192.168.3.232:32973
.............www.google.ca............./....www.google.com..
+...........www.google.akadns.net.
#
U 192.168.3.232:32975 -> 66.48.69.3:53
.?...........www.google.ca.....
#
U 192.168.3.232:32975 -> 192.168.2.4:53
.?...........www.google.ca.....
#
U 192.168.2.4:53 -> 192.168.3.232:32974
.?...........www.google.ca............./....www.google.com..
+.......~...www.google.akadns.net..G............'..G............'c.G............'h
#
U 192.168.3.232:32976 -> 66.48.69.3:53
.?...........www.google.ca.....
#
U 192.168.3.232:32976 -> 192.168.2.4:53
.@...........www.google.ca.nodes.net.ad-flow.com.....
#
U 192.168.2.4:53 -> 192.168.3.232:32976
.@...........www.google.ca.nodes.net.ad-flow.com......$......QY...$.dns.
$wt%F...............c
#
U 192.168.3.232:32976 -> 192.168.2.4:53
V............www.google.ca.....
#
U 192.168.2.4:53 -> 192.168.3.232:32975
.?...........www.google.ca............./....www.google.com..
+.......y...www.google.akadns.net..G............'..G............'c.G............'h
#
U 192.168.3.232:32978 -> 66.48.69.3:53
V............www.google.ca.....
#
U 192.168.3.232:32978 -> 192.168.2.4:53
V............www.google.ca.....
#
U 192.168.2.4:53 -> 192.168.3.232:32976
V............www.google.ca............./....www.google.com..
+.......z...www.google.akadns.net.
#
U 192.168.3.232:32980 -> 66.48.69.3:53
V............www.google.ca.....
#
U 192.168.3.232:32980 -> 192.168.2.4:53
V............www.google.ca.nodes.net.ad-flow.com.....
#
U 192.168.2.4:53 -> 192.168.3.232:32980
V............www.google.ca.nodes.net.ad-flow.com......$......Qx...$.dns.
$wt%F...............Y
#
U 192.168.2.4:53 -> 192.168.3.232:32978
V............www.google.ca............./....www.google.com..
+.......u...www.google.akadns.net.



how else can i debug this? is it possible a recent emerge could have done
this? please help. my box is handicapped.


--
I hate to bring up our imminent arrest in the middle of your CRAZY TIME, but
we have to leave, now.
- Mal to Saffron/Bridget/Yolanda, Firefly, "Trash"

--
gentoo-user@gentoo.org mailing list
Re: flaky / sparatic dns [ In reply to ]
On Tue, 5 Oct 2004 12:22:04 -0400, daniel <danstemporaryaccount@yahoo.ca> wrote:
> i'm not sure when it started, but my dns is officially flakey. sometimes
> sites just won't resolve, and others, it'll take a very long time. my first
> thought was of course: gibbled dns server(s). but no one else in the office
> is having the same problem.
>
> so then i tried a few simple tests:
>
> (2004-10-05 12:13:51) $ host forums.gentoo.org
> forums.gentoo.org has address 140.211.166.164
> (2004-10-05 12:13:57) $ host forums.gentoo.org
> forums.gentoo.org has address 140.211.166.164
> (2004-10-05 12:13:57) $
>
> the first request took 6 seconds (short compared to some others) but the
> second not even a second. but this isn't the big problem. the delay is most
your dns server had to query some other dns servers for the answer and it took
him 6sec to do it. as for the second query, it had the answer cached
and answered
immediately.
> noticeable when using a program like konqueror to retrieve a page. it
> literally can take about 30seconds.
bummer
> so wondering what was going on, i ran ngrep. it took 17seconds to decide
> www.google.ca didn't exist, and after a refresh, another 10 seconds to load
> the page (with a dead image). here's what ngrep said:
[...]
from what you've posted looks like you're using 2 dns servers. one
private and one public.
the first one didn't know the answer and so the second one was asked
(or something like
that)

maybe look for multiple 'search' entries in your resolv.conf?

try to use command 'dig' to debug your dns setup (man dig) instead of ngrep.

--
Regards
Karol Krzak

--
gentoo-user@gentoo.org mailing list