Domain Name & Domain Name System (DNS)

We discussed what is a domain name, and what purpose does it serve on the world wide web. So we have domain name that points to an IP Address of a web server, which is used for hosting a website. The key element that is used for domain name resolution from domain name to IP Address is Domain Name System (DNS) which we are going to read about now... (i.e. if you are interested - :))

What does Domain Name System (DNS) Do?
We all have used phone directory, or as you have in mobiles, or computers now - an address book. Imagine if you could only save telephone numbers without the ability to associate that number to any name, Scary thought isn't it!!! Well a domain name system does exactly the same thing that an address book does. So while you search for a name to place a call, internally your mobile is going to dial the mobile number associated with the name that has been stored by you. On the World Wide Web, this address book is the Domain Name System (DNS) that translates domain name like http://www.vu2.in to it's IP Address like eg. 209.51.196.242 for the browser and all associated networking components need to establish a connection, fetch information or deliver information from your machine to server and from the web server to your machine. Further to address book analogy for Domain Name System, just like you have the ability to store a contacts name, date of birth, anniversary information, Email Address etc, similarly a Domain Name System (DNS) stores list of mail exchange servers that would accept email for particular domain name apart from other entries for a particular domain.

How does Domain Name System (DNS) work?
In computers, files store information, and these files have a structure that is similar to trees, thus the data structure is called a tree, where each leaf of the tree represents information for a domain. The information thus stored for a domain name is called a resource record. The tree is further divided into zones. A zone is made up of such leaves, or normally called nodes which are served by an authoritative DNS nameserver. The Domain Name System consists of a set of DNS Servers. Each domain or sub domain would have one or more authoritative DNS server to provide relevant information about that domain, and the name servers of any domains beneath it. The starting point is the main nameserver - technically known as root nameserver. Root Nameserver is the server which handles the query to resolve a top level domain (TLD) name like http://www.vu2.in.

How do you find IP Address for a domain name?
If you wonder how to find an IP Address for a given domain name, all you have to do is to use command prompt and make use of any of the following command to get the actual IP being used.
1. PING
When you ping a domain name, you would instantly get IP Address of the Domain (after resolution by DNS) as shown below:
Microsoft Windows XP [Version 5.1.2600]
(C) Copyright 1985-2001 Microsoft Corp.
C:\>ping www.vu2.in

Pinging www.vu2.in [209.51.196.242] with 32 bytes of data:...

2. TRACERT
Like ping, tracert utility also allows you to fetch IP Address associated with a domain name as shown below

C:\>tracert www.vu2.in

Tracing route to www.vu2.in [209.51.196.242]
over a maximum of 30 hops:
1 One thing we must bear in mind is that while domain names are unique, multiple websites could share same hostname. Virtual hosting is used to host multiple websites on one machine or web server, and hence there is no one-to-one relationship between hostname and IP Address.

Finally a quick recap
a. DNS : Domain Name System (DNS)
b. Address Book for websites on the internet.
c. Stores mapping of domain name with IP Address / web server information.
d. Information for each domain name is stored in a tree like data structure on DNS Server.
e. Each leaf stores record for one domain name.
f. These leaves are called resource records.
g. Collection of leaves make up a zone.
h. Domain Name System (DNS) stores other information as well apart from name resolution.
i. You can get IP address for any domain using utilities like PING or TRACERT.

Next we would look at how things were before Domain Name System (DNS) came into existence ... Keep watching this space for more :)

Webmaster
[pubdomains.in | pubdomains.com | pubwebhost.com | finehost.in | pubdomainshost.com | pubdomainshost.in]

Why use a Domain Name?

A domain name is a unique word combination used as identifier to identify a web site on the World Wide Web. While computers talk in the binary language (I hope you know this one -- There are 10 types of people.. those who understand binary, and those who don't). OK so back to language computers communicate in, and language we use to communicate. Now, each computer on the world wide web (WWW) is identified by a unique 32bit number (which can be permanent, also called static IP or temporary, or dynamic IP).

A typical IP address looks like 121.001.003.005.

This representation with 4 decimal numbers (also called octets), are separated by dots and this format is known as "dotted quad" or "dotted decimal" notation.

Now you may ask what has "dotted quad" got to do with domain name? Well imagine if you were to remember and type 72.14.207.99 in the address bar every time you had to do a search? So what is easy to remember the decimal representation or something you are so familiar with, simply known as Google Search?

So back to what is the purpose of a domain name, it is a easy to remember word representation of the unique 32 bit identifier for a machine connected to the internet. Not every machine can serve you web pages though... The machine has to have a software running to churn out web pages, and thus is called a web server.

Just like 32bit unique identifier, each domain name is unique - and maintained by registrars... So if you have not bought a domain name for your business, and someone else is using it, you have missed out the opportunity for your online showroom!!! Your domain name serves as a visiting card for your existing and new customers to display the services rendered by you, your company or the products that you manufacture, or complete information on your office, location, address contact nos. etc... It is only limited by your imagination to use it the way you want it!!!

As I explained how machines talk with each other in binary language of one's and zero's, and how any computer on the world wide web has an IP address, you may wonder how do we associate a domain name with IP address? OK, the answer lies in machines dedicated to perform this translation for you - known as DNS Servers. When a domain name is entered into address bar of a web browser, request goes to a Domain Name System (DNS). The DNS translates the domain name into an IP address then the appropriate site is sought out. All these transactions remain transparent to You the end user; however in the back ground this translation takes place to display web pages from the domain name that you enter in the web browser.

So to summarize why we use a domain name, as you would recollect.
1. Each computer connected on the network is represented by an IP Address.
2. Each IP Address internally is made of "dotted quad".
3. Dotted Quad representation is also known as "dotted decimal".
4. A sample IP address is of the type 111.222.333.444 - a unique 32bit number.
5. Domain name is a simple word(s) representation of IP Address of web server.
6. A web server is a dedicated computer for presenting web pages. [more on this later...]
7. When you type a domain name, like google.com, the request is first sent to a DNS Server.
8. DNS Server translates the word google.com to it's IP address, and thus you don't have to remember IP Address of computers.
9. Domain Name is unique - No 2 sites can have same domain name (just like IP address is unique)
10. Domains are maintained by domain registrars (like my service on pubdomains.com & pubdomains.in)
11. A sample website on amateur radio has IP address (dynamic IP Address, ie, it may change over a period of time) is 209.222.7.10.
12. It is easy to remember domain name instead of IP address.


So .. you may browse a website by its IP Address or its domain name, but as I mentioned, it is easy to remember format, ie words, or string of words, thus a domain name is used all over the internet...

So long,
happy domain'ing