Hello Eduardo, this is a known bug in probably libc in CentOS6 or equivalent RHEL. Workaround is to disable recvmmsg backend on configure with configure flag "--enable-recvmmsg=no" $ cd knot-src $ autoreconf -if $ ./configure --enable-recvmmsg=no $ make && sudo make install For more information see: https://bugzilla.redhat.com/show_bug.cgi?id=760177 Please let me know if it works for you. Kind regards, Marek -- Marek Vavruša Knot DNS CZ.NIC Labs http://www.knot-dns.cz ------------------------------------------- Americká 23, 120 00 Praha 2, Czech Republic WWW: http://labs.nic.cz http://www.nic.cz On 17 September 2012 11:34, Eduardo Duarte &lt;eduardo.duarte(a)fccn.pt&gt; wrote: > Hello, > > I have setup a KNOT dns server but I'm having troubles with the UDP queries. > The server is not answering to the UDP queries but it is answering to > queries in TCP. > The server is running on a CentOS release 6.3 (Final) and the configuration > file is the following. > *************knot.conf*********** > system { > identity "Yet.another.server"; > nsid "Yet.another.server"; > storage "/opt/knot_run/knot-minimal"; > pidfile "/opt/knot_run/knot.pid"; > user root; > } > > interfaces { > ipv4 { address 127.0.0.1@53; } > ipv4 { address 193.137.197.25@53; } > } > > remotes { > ns-test01 { address 193.136.192.86@53; } > ns-test02 { address 193.136.192.87@53; } > ns-test03 { address 193.137.196.30@53; } > ns-test04 { address 193.137.196.31@53; } > } > > zones { > > zonetest-01.dns.pt { > file "/opt/knot_run/zones/zonetest01"; > xfr-in ns-test01; > notify-in ns-test01; > } > > zonetest-06.dns.pt { > file "/opt/knot_run/zones/zonetest06"; > > } > } > > log { > file "/opt/knot_run/log/knot.log" { any all; } > } > ********************************** > The output of the log file is > ********knot.log****************** > 2012-09-17T10:25:40.208574+01:00 Stopping server... > 2012-09-17T10:25:40.210677+01:00 Server finished. > 2012-09-17T10:25:40.211260+01:00 Shut down. > 2012-09-17T10:25:40.230967+01:00 Binding to interface 127.0.0.1 port 53. > 2012-09-17T10:25:40.231283+01:00 Binding to interface 193.137.197.25 port > 53. > 2012-09-17T10:25:40.232162+01:00 Loading 2 compiled zones... > 2012-09-17T10:25:40.233783+01:00 Loaded zone 'zonetest-01.dns.pt.' > 2012-09-17T10:25:40.237553+01:00 Loaded zone 'zonetest-06.dns.pt.' > 2012-09-17T10:25:40.238983+01:00 Loaded 2 out of 2 zones. > 2012-09-17T10:25:40.239044+01:00 Configured 2 interfaces and 2 zones. > 2012-09-17T10:25:40.239078+01:00 > 2012-09-17T10:25:40.239111+01:00 Starting server... > 2012-09-17T10:25:40.240688+01:00 Server started as a daemon, PID = 8599 > 2012-09-17T10:25:40.240772+01:00 PID stored in /opt/knot_run/knot.pid > ********************************* > And an example of the query's > ********************************* > [root@ns-test06 ~]# dig @127.0.0.1 zonetest-06.dns.pt +tcp > > ; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6_3.1 <<>> @127.0.0.1 > zonetest-06.dns.pt +tcp > ; (1 server found) > ;; global options: +cmd > ;; Got answer: > ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 30969 > ;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 5, ADDITIONAL: 0 > ;; WARNING: recursion requested but not available > > ;; QUESTION SECTION: > ;zonetest-06.dns.pt. IN A > > ;; ANSWER SECTION: > zonetest-06.dns.pt. 3600 IN A 193.137.196.42 > > ;; AUTHORITY SECTION: > zonetest-06.dns.pt. 3600 IN NS ns-test01.dns.pt. > zonetest-06.dns.pt. 3600 IN NS ns-test02.dns.pt. > zonetest-06.dns.pt. 3600 IN NS ns-test03.dns.pt. > zonetest-06.dns.pt. 3600 IN NS ns-test04.dns.pt. > zonetest-06.dns.pt. 3600 IN NS ns-test06.dns.pt. > > ;; Query time: 2 msec > ;; SERVER: 127.0.0.1#53(127.0.0.1) > ;; WHEN: Mon Sep 17 10:25:49 2012 > ;; MSG SIZE rcvd: 202 > > [root@ns-test06 ~]# dig @127.0.0.1 zonetest-06.dns.pt > > ; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6_3.1 <<>> @127.0.0.1 > zonetest-06.dns.pt > ; (1 server found) > ;; global options: +cmd > ;; connection timed out; no servers could be reached > ********************************* > > Can anyone help me with this problem? > > Best regards, > > -- > Eduardo Duarte > SIT-DNS > DNS.PT - https://www.dns.pt/ > FCCN - http://www.fccn.pt/ > > _______________________________________________ > knot-dns-users mailing list > knot-dns-users(a)lists.nic.cz > https://lists.nic.cz/cgi-bin/mailman/listinfo/knot-dns-users