Showing posts from May, 2012

Troubleshooting DNS Server

Related to Previous Article:

If you are unable to dig properly to your own Test DNS Server (Lab only, not a live DNS Server), here are some tips -

Check whether the named service is running.
[root@ns1 named]# service named status version: 9.7.0-P2-RedHat-9.7.0-5.P2.el6 CPUs found: 1 worker threads: 1 number of zones: 17 debug level: 0 xfers running: 0 xfers deferred: 0 soa queries in progress: 0 query logging is OFF recursive clients: 0/0/1000 tcp clients: 0/100 server is up and running named (pid 1235) is running...
Check whether the FQDN is properly set in /etc/sysconfig/network and /etc/hosts
[root@ns1 named]# cat /etc/sysconfig/network NETWORKING=yes HOSTNAME=ns1.testdom.inv GATEWAY= [root@ns1 named]# cat /etc/hosts localhost localhost.localdomain localhost4 localhost4.localdomain4 ::1 localhost localhost.localdomain localhost6 localhost6.localdomain6 ns1…

Primary DNS Server in CentOS 6 (without chroot)

Objective We would be configuring the primary DNS Server for the domain testdom.inv (yes, the top level domain is inv i.e. 'invalid').  The FQDN (Fully Qualified Domain Name) of the server is ns1.testdom.inv. This is a simulation, so you better get your Server off the Internet-
make sure the Server does not have any real IPmake sure that the file /etc/resolv.conf does not contain any IP address of a valid DNS Server.
Here is the IP Database
DNS Server Server Server
Procedure Phase1: The first thing when it comes to configuring any Server is setting up the hostname of the Server properly. We have to modify the following lines in the mentioned files -

[root@centu ~]# vim /etc/sysconfig/network HOSTNAME=ns1.testdom.inv
[root@centu ~]# vim /etc/hosts ns1.testdom.inv ns1
Changing hostname like this sometimes takes effect after a Server reboot. To a…

How DNS Works

Domain Name SystemA newer version of this article is available in my blog.

In any network, the hosts primarily communicate between each other through IP addresses. For example, if my computer is doing a google search, my computer is actually communicating with the IP address of one of the web servers of However, even if the computer is efficient with numbers, humans on the other hand work better with names. For this reason, the TCP/IP protocol includes the Domain Name System (DNS)  to link between IPs and computer names i.e. hostnames. The DNS is a distributed database of computers that is responsible for resolving hostnames against IP addresses and vice-versa.
Any DNS query involves two parts. The Resolver: The resolver forms up or initiates the query. The resolver itself does not run as a program. /etc/resolv.conf is an example of a resolver. Name Server: The Name Server is the service running in the server that responds to the DNS query generated by the resolver i.e.…

Using Citycell Zoom in Ubuntu

Thank you Anirban Da for sharing the information.

Ubuntu has proven again that it's one of the most user friendly operating systems. Using Citycell Zoom in Ubuntu is very easy.

Here's how it's done:
Click on the network icon on the upper right corner of the screen
Go to Edit Connections > Mobile Broadband > Add ContinueSelect country from the list Select the service provider FinishWhen prompted for username and password combination, type in the following:username: wapspassword: waps Now anytime you wish to connect using zoom, go to the network icon and use your citycell connection for surfing. Hope this helps.