DNS | How Does DNS (Domain Name System) work ??

In field the ethical hacking or in computer networking field, you will often come across the term Domain Name System or Domain Name Service which is simply referred to as DNS. Understanding the concept of DNS is very much essential especially if you wants to get into the filed of network security or ethical hacking. Today in this article, I am going to explain working of Domain Name Servers(DNS) in very easy and in simple manner so normal readers who have only basic knowledge of networking filed can also easily understand it.

What is DNS??

DNS is basically a protocol within the set of standards for how computers exchange data or information on private networks and on the Internet, known as the TCP/IP protocol suite. Basic job of DNS is to turn a user-friendly domain name like "wildhacker.com" into an Internet Protocol (IP) address like 73.25.61.12 which computers uses to identify each other on the internet network.

Computers and other network devices on the Internet has a unique IP address allotted to it. This is like phone number but in this case you don't have to keep your own address book of IP addresses. IP address is used to establish connections between the server computer and the client computer in order to initiate the transfer of data between two computer machine. Sending an email or accessing a website DNS plays a very important role.Whenever you try to accessing a Web site or sending e-mail, your computer uses a DNS server to look up the domain name you're trying to access. This whole process is called DNS Resolution.

For example, when you type “www.wildhacker.com” in your browser’s address bar, your computer will fetch the IP address of wildhacker server that is “73.25.61.12″ using DNS server. After obtaining the IP address, your computer will then establish a connection with the server only after that wildhacker website page will start loading in your browser.

There are millions of websites on the Internet in the world, So it is impossible for peoples to remember the IP address of every website in order to access it. Therefore, the concept of domain name was introduced, the concept domain name give unique name to every website in the world which makes it easy for people to remember. However, the IP address is still used as the base for internal communication by networking devices. This is where the DNS comes in to action that works by resolving the user friendly domain name to its corresponding machine friendly IP address. In simple words, domain names are for humans while IP addresses are for network devices. The “Domain Name System” is a protocol to establish a link between the two.

You can always bypass a DNS lookup by entering 73.25.61.12 directly in your browser (give it a try). However, you're probably more likely to remember "wildhacker.com" when you want to return later. In addition, a Web site's IP address can change over time, and some sites associate multiple IP addresses with a single domain name.

Types Of Domain Name System (DNS) Servers :

There are two type of Domain Name System (DNS) Servers,

1: Root Name Servers 

The root servers represent the top level hierarchy of the DNS. This top level DNS servers contain the complete database of domain names and their corresponding IP addresses. Currently, there are 13 root servers distributed globally

( A map of the 13 logical nameservers, including anycast instances, the end of 2006. )

2: Local Name Servers

Local servers represent the most lower level DNS servers that are owned and maintained by Internet Service providers (ISPs) and many business organizations. These local servers are able to resolve frequently used domain names into their corresponding IP addresses by caching the recent information.

How DNS Server Works?

• You type a URL such as “http://www.wildhacker.com” on your browser’s address bar.
• After getting request computer will send a request to the local name server to resolve the domain name into its corresponding IP address. This request is often referred to as a DNS query.
• The local name server will receive the query to find out whether it contains the matching name and IP address in its database.
• If found, the corresponding IP address (response) is returned.
• If not, the query is automatically passed on to another server that is in the next higher level of DNS hierarchy.
• If lower level DNS server does not contain the record for a given domain name then the DNS quert eventually reaches one of the root name server to obtain the response.
• This process continues until the query reaches the server that contains the matching name and IP address.
• The IP address (response) then flows back the chain in the reverse order to your computer.

Whenever a new domain name is registered or an existing one is updated anywhere in the world, the information about that domain must get updated on all the major DNS servers so that the domain can be reached from all parts of the globe. This is called DNS propagation. This whole process of updation can take minimum 24 hr to maximum 72 hours to get completed. DNS servers updation time not fixed, It is usually depends on the organization such as the ISP that maintains the server. Most DNS servers are updated on an hourly basis while some may update their databases on a daily basis.

So far, you've read about some important DNS basics.Now I hope you have now understood the basic working of DNS. If you have any question in your mind then feel free to mention it in comments bellow.

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