nixCraft

kumarat9pm · #1 (**permalink**) 18th November 2009, 11:16 AM

Hi all,

I am facing an issue with DNS server.. I am seeing slow resolutions from our Public DNS servers.. how to resolve this issue?
i know one issue is.. if there is no reverse lookup zone file is not there on server this type of problems we will be facing..
Note:reverse lookup zones files for this dns server is with ISP..
is it mandatory not to configure reverse lookup zone files on server and giving them to ISP?
i am bit confused please share your thoughts/inputs how to resolve this issue.
Can we see any logs of dns servers in any file other then /var/log/messages?

jaysunn · #2 (**permalink**) 19th November 2009, 05:21 AM

Hey kumarat9pm,

I just went through trying to find log files other than /var/log/messages today.

On RHEL, you can run

Code:

/etc/init.d/named status

Or play with the file /etc/named.conf

Code:

logging {
        category security { default_syslog; };
        category lame-servers { null; };
        category queries { null; };
};

I know there is a way to open this up to more debugging options. I have mine set to null, however you can change this. Have a look at changing the logging on BIND and make sure you restart named when you make the changes.

Also have a look at these tools:

Code:

[root@dns1 ~]# named
named            named-bootconf   named-checkconf  named-checkzone

And this link:

Check BIND – DNS Server configuration file for errors with named-checkconf tools

HTH,

Jaysunn

kumarat9pm · #3 (**permalink**) 19th November 2009, 06:33 AM

Ya may be that is true to get more info on named.conf file logging.. will try to get some more info on this.. and the mention syntax checking commands will not help me any thing bcz all ready my DNS server is working fine expect slow resolutions..

nixcraft · #4 (**permalink**) 19th November 2009, 10:50 AM

Reverse zone belongs to people who control IP address. If ip address leased from ISP, they will control reverse zone. For example, nixcraft.com is resolved by ns{1,2}.nixcraft.net. But its ip reverse lookup is 75.126.168.152 is done by ISP name servers as IP belongs to them.

As far as speed turn on debugging as suggested by above poster. Another geeky and recommend option is to run tcpdump on # 53 and see what is going on.

kumarat9pm · #5 (**permalink**) 23rd November 2009, 11:01 AM

Here the problem is on Firewall of my company..
we have 2 NS server. ns1 is properly mapped to the name server one, where as ns2 is mapped to one of the ftp severs

.. so its unable to resolve the hostnames.. now we changed the mappings to proper DNS servers.. now its working like charm..
Thanks once again..

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Slow resolutions from DNS server

[Solved] Slow resolutions from DNS server

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kumarat9pm (19th November 2009)