On today's exercise, we learned how to configure DNS(Domain Name System) servers. The Domain Name System acts like an internet directory service wherein the IP address is connected to its appropriate domain name. So whenever we look up a website, we access them by typing its domain names rather than their real IP addresses. 

In order for us to simulate how the domain name system works we followed some steps and along the way we learned the process and mechanism of the DNS. 

We start off with entering this commands to the terminal (linux box) : 

     $sudo -s
     #apt-get install bind9
     #cd /etc/bind
     #ls

BIND9 is a version of BIND which means the Berkeley Internet  Name Domain. BIND is an implementation of the protocols in DNS. It provides an open-source redistributable reference implementation of the major components of a DNS which includes a Domain Name System Server, Domain Name System Resolver library,
and tools for managing and verifying of the proper operation of the DNS server (Reference: www.bind9.net)

After that, we begin with configuring the active interface with a static IP address that is 192.168.3.X, where X is our seat number in the lab using the command ifconfig:

   ifconfig eth0 192.168.3.13 netmask 255.255.255.0 broadcast 192.168.3.255

After we have done that, we proceeded with configuring /etc/bind/named.conf.local with the appropriate domain name, filename of forward and reverse zone files. For the class, we used cmscwantriseben.com as our domain name. 

Using VI (a text editor inside the terminal commonly used for programmers), the  /etc/bind/named.conf.local was configured with its appropriate parameters. 

Afterwards, we proceed with getting the IP addresses, forward and reverse zone files of our other classmates. As you can see here in this image their domain names and IP addresses are like added to the "directory" of computer networks that you can connect and "ping" to afterwards. 

And then, we entered the reverse zone files of our classmates domain names.

After we have done this we proceed with checking the configuration files if there are errors or not. At first, I have gained too many errors but resolved it with the use of the following commands: named-checkconf, named-checkzone

named-checkconf is a named configuration file syntax checking tool or simply checking the syntax of the configuration files. 

**named, is used on the vast majority of name serving machines on the Internet, providing a robust and stable architecture on top of which an organization's naming architecture can be built.(Reference: www.bind9.net)

named-checkzone is a zone file validity checking tool or converting tool. 

At first the result after I entered named-checkconf there were errors but I resolved it and after that, it didn't produce any results meaning there were no more errors. like here:

After this, we proceed with starting the server using the command /etc/init.d/bind9 restart

I really don't know the details of this command but I think it starts the DNS server we had been configured earlier. You can see it here in this image:

And then we need to specify the DNS server that will be used by the resolver by editing the file, /etc/resolv.conf resolv.conf is as follows: 

The edited version of /etc/resolv.conf goes like this:

After that we proceed with dig. DIG  is a DNS lookup utility, it looks whether the domain name you entered exists and it is also used for querying DNS servers with different queries. 

This is how I DIG my classmates' DNS: 

After this process I began testing the domain names of myself and my classmates by the means of ping. 
ping is sending ICMP ECHO_REQUEST to network hosts (the local computers of my classmates are the other hosts in the network) 

This is when i "pinged" myself

and my other classmates as follows:

After this we proceed with the cleanup by entering the following commands:

removing entries in /etc/bind/named.conf.local using vi

rm /etc/bind/<forward zone file>

rm /etc/bind/<reverse zone file>

removing entries in /etc/resolv.conf using vi

#history -c

And after all of this, the exercise is already done. I have experienced and learned how the domain name system works and how to connect with other domain names. Because of this, I had understood better how we access websites in the internet. It gave me a better understanding on it. At first, I thought that I would fail doing the exercise and fail with the goals to meet at the end of the exercise but luckily, I have finished well and understood most of the aspects of a domain name system.