DNS(Domain Name System )

Domain Name System (or Service or Server), an Internet service that translates domain names into IP addresses. Because domain names are alphabetic, they're easier to remember. The Internet however, is really based on IP addresses. Every time you use a domain name, therefore, a DNS service must translate the name into the corresponding IP address. For example, the domain name www.example.com might translate to 198.105.232.4.
 Ex. the google.com has 6 ip adresses....
                                                           74.125.236.50
                                                           74.125.236.48
                                                           74.125.236.51 
                                                           74.125.236.49
                                                           74.125.236.52 
ip adresses are like phone numbers and dns is the names associated with ip adresses....like amit mob. 09458703039

The DNS system is, in fact, its own network. If one DNS server doesn't know how to translate a particular domain name, it asks another one, and so on, until the correct IP address is returned.

 The nslookup   command :

nslookup is a network administration command-line tool available for many computer operating systems for querying the Domain Name System (DNS) to obtain domain name or IP address mapping or for any other specific DNS record.
       Basically the nslookup cammand is used for querying the ip adresses and name servers of a website...
 Ex. The following example queries the Domain Name System for the IP address of the domain name google.com by issuing the command nslookup google.com.

here is how you can see ip adresse of a website on your own pc..

step::> startmenu -> run -> command prompt

c:\user\amit> nslookup
 Default Server:  dsldevice.lan
 Address:  192.168.1.1
 

::note:: if you are using your college server then u need 

to change the server otherise if u r using 

modem or other device this is not required..
 > server 8.8.8.8
 Default Server:  google-public-dns-a.google.com
 Address:  8.8.8.8
 
 > set q=a  (a for querying ip adress) 
 > google.com
 Server:  [8.8.8.8]
 Address:  8.8.8.8
 
 Non-authoritative answer:
 Adresses:                   74.125.236.48 

                                                           74.125.236.48

                                                           74.125.236.51 

                                                           74.125.236.49

                                                           74.125.236.52 

 it shows that google uses 6x ip adresses.........

:: now lets see how to know name servers of google.... 


:: to see the name server of google we just need to replace....
   >set q=ns  (ns for name server)

 it shows that google has four name servers as.....  ns4.google.com
                                                                               ns3.google.com
                                                                               ns2.google.com
                                                                               ns1.google.com 

for every new domain there are atleast two name servers 
1:> primary domain name server 
2:> Secondary domain name server

PS:>  just follow the above steps and try to find your college name servers and post in comments....:)