Troubleshooting DNS

Many data centers (including Sago Networks) do not delegate RDNS to the server for security reasons. However, most DC’s will make the change for you manually if you ask then nicely and the RDNS a is legitimate.

If you want to change the RDNS setting submit a support ticket with the following info:

<< IP Address >> << Desired RDNS Record >>

e.g 125.262.231 mybox.com

The first thing to do is to query the dns servers directly to see if they are advertising the right info. If they are then the problem lies elsewhere.

From the shell, run:

nslookup > server <IP of your IWorx-CP iterative DNS server> > domain-to-query.com

The above IP after the ‘server’ directive should be an IP bound to your iworx-cp box that you’re expecting to answer queries and that has a dns service on it as listed in the dns overview page.

If this times out:

First, check to make sure djbdns is up:

service djbdns status

Make sure that ALL of your IP‘s are listed in the output of the above command.

If that is not the problem, then there is a problem somewhere on the internet

First verify that djbdns is installed

[root@iworx root]# rpm -q djbdns
djbdns-1.05-100.cos3x.iworx
[root@iworx root]#

and running

[root@iworx root]# service djbdns status
/service/tinydns-66.118.142.14: up (pid 6298) 8289647 seconds
/service/tinydns-66.118.142.15: up (pid 6300) 8289647 seconds
[root@iworx root]#

If this is not the problem then turn off your firewall and see if that helps

[root@iworx root]# service apf stop
Stopping APF: [ OK ]
[root@iworx root]#

If stopping your firewall fixes the problem then you need to make sure port 53 is open in your firewall.

If it doesn’t work take a look at your resolv.conf

[root@iworx root]# cat /etc/resolv.conf
nameserver 127.0.0.1
[root@iworx root]#

This is exactly what you should see -- you should NOT see a list of your IP‘s.

If your dns server is NOT installed you will need to reinstall it. To do so you will need to TEMPORARILY edit resolv.conf to work with an external resolver like so

[root@iworx root]# vi /etc/resolv.conf
# nameserver 127.0.0.1
nameserver 66.118.128.158
[root@iworx root]#

Note that the line nameserver 127.0.0.1 is commented out but NOT removed. You will need to restore this setting when we are done. The second line needs to contain the IP address of another working DNS server. The example is the customer nameserver belonging to sagonet.com

Then run:

[root@iworx root]# service ntpd restart
Shutting down ntpd: [ OK ]
Starting ntpd: [ OK ]
[root@iworx root]#

YUM should work now.

Then run

[root@iworx root]# yum install djbdns

and

[root@iworx root]# service djbdns start

• If this works, restore your /etc/resolv.conf file to it’s orignal state.
• Then restart ntpd again.