BIND non-cached resolution taking 2-4 seconds each time
Mark Andrews
Mark_Andrews at isc.org
Tue Sep 19 04:31:15 UTC 2006
No. He is just running old software.
1773. [bug] Fast retry on host / net unreachable. [RT #13153]
> ee99ee at gmail.com wrote:
> > I'm having a problem with BIND 9 taking FOREVER to resolve DNS
> > requests. Both are fresh installs of CentOS on PIII hardware. Both are
> > in a well connected network (2 full DS-3's that aren't very used from
> > two providers; we do our own BGP).
> >
> > Here is my named.conf:
> >
> > ------------------------------------
> > acl recurseallow {
> > 208.67.56.0/22;
> > 127.0.0.1;
> > };
> >
> > acl trusted {
> > };
> >
> > options {
> > directory "/var/named";
> > allow-transfer { trusted; };
> > allow-recursion { recurseallow; };
> > query-source port 53;
> > };
> >
> > include "/etc/rndc.key";
> >
> > zone "." {
> > type hint;
> > file "named.root";
> > };
> > ------------------------------------
> >
> > Here is my root hints file:
> > ------------------------------------
> > 6D IN NS A.ROOT-SERVERS.NET.
> > 6D IN NS B.ROOT-SERVERS.NET.
> > 6D IN NS C.ROOT-SERVERS.NET.
> > 6D IN NS D.ROOT-SERVERS.NET.
> > 6D IN NS E.ROOT-SERVERS.NET.
> > 6D IN NS F.ROOT-SERVERS.NET.
> > 6D IN NS G.ROOT-SERVERS.NET.
> > 6D IN NS H.ROOT-SERVERS.NET.
> > 6D IN NS I.ROOT-SERVERS.NET.
> > 6D IN NS J.ROOT-SERVERS.NET.
> > 6D IN NS K.ROOT-SERVERS.NET.
> > 6D IN NS L.ROOT-SERVERS.NET.
> > 6D IN NS M.ROOT-SERVERS.NET.
> > A.ROOT-SERVERS.NET. 6D IN A 198.41.0.4
> > B.ROOT-SERVERS.NET. 6D IN A 128.9.0.107
> > C.ROOT-SERVERS.NET. 6D IN A 192.33.4.12
> > D.ROOT-SERVERS.NET. 6D IN A 128.8.10.90
> > E.ROOT-SERVERS.NET. 6D IN A 192.203.230.10
> > F.ROOT-SERVERS.NET. 6D IN A 192.5.5.241
> > G.ROOT-SERVERS.NET. 6D IN A 192.112.36.4
> > H.ROOT-SERVERS.NET. 6D IN A 128.63.2.53
> > I.ROOT-SERVERS.NET. 6D IN A 192.36.148.17
> > J.ROOT-SERVERS.NET. 6D IN A 198.41.0.10
> > K.ROOT-SERVERS.NET. 6D IN A 193.0.14.129
> > L.ROOT-SERVERS.NET. 6D IN A 198.32.64.12
> > M.ROOT-SERVERS.NET. 6D IN A 202.12.27.33
> > ------------------------------------
> >
> > Here is the output of TCP dump doing a sample query after running "rndc
> > flush" then "dig @localhost theplanet.com"
> >
> > ------------------------------------
> > 08:50:04.249815 IP 208.67.56.6.domain > 193.0.14.129.domain: 11509%
> > [1au] A? theplanet.com. (42)
> > 08:50:04.251185 IP 208.67.56.6.domain > 193.0.14.129.domain: 6690%
> > [1au] NS? . (28)
> > 08:50:04.393408 IP 193.0.14.129.domain > 208.67.56.6.domain: 11509-
> > 0/13/16 (530)
> > 08:50:04.394688 IP 193.0.14.129.domain > 208.67.56.6.domain: 6690*-
> > 13/0/14 NS a.root-servers.net.,[|domain]
> > 08:50:06.397444 IP 208.67.56.6.domain > 192.55.83.30.domain: 13032%
> > [1au] A? theplanet.com. (42)
> > 08:50:06.651124 IP 192.55.83.30.domain > 208.67.56.6.domain: 13032
> > FormErr- [0q] 0/0/0 (12)
> > 08:50:06.651819 IP 208.67.56.6.domain > 192.55.83.30.domain: 3266 A?
> > theplanet.com. (31)
> > 08:50:06.909213 IP 192.55.83.30.domain > 208.67.56.6.domain: 3266-
> > 0/2/12 (259)
> > 08:50:06.910512 IP 208.67.56.6.domain > 207.44.128.230.domain: 17183%
> > [1au] A? theplanet.com. (42)
> > 08:50:06.956252 IP 207.44.128.230.domain > 208.67.56.6.domain: 17183*-
> > 1/2/13 A 70.87.6.11 (286)
> > ------------------------------------
> >
> >
> > Notice the 2 second delay between lines 4 and 5? The result took 2.5
> > seconds for dig to respond. Once it's cached, it takes only a few ms to
> > get the same thing back, it's just that first time query that takes
> > FOREVER.
> >
> >
> Well, you're running on a PIII, and after a flush, named has to
> re-create the whole cache structure -- notice the "priming" queries for
> the root zone which are occurring in parallel with the attempt to
> resolve theplanet.com. Could it just be that your box *normally* takes 2
> seconds to initialize its cache?
>
> Flushes or restarts usually don't happen very frequently, so what's
> really the problem here?
>
>
> - Kevin
>
>
--
ISC Training! October 16-20, 2006, in the San Francisco Bay Area,
covering topics from DNS to DHCP. Email training at isc.org.
--
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742 INTERNET: Mark_Andrews at isc.org
More information about the bind-users
mailing list