Domain Name Servers, also called as DNS are very essential for internet. DNS is a intermediate computer/ service which helps us to find and connect to the desired web site.
As we know, a website is not in a virtual place. We feel like that we are connecting to a virtual space, but what happens is we are connecting to another computer which holds the data about the website.
Lets take www.srilanka.lk as an example. If we need to create a website for public use, we will have to create a website and share it with public. Then we have to store the website on our computer and share it. But the problem is we have to keep the computer 24/7 on and connected to the internet. We will have to create more backup systems to use if our primary service is gone offline. We need to have a good, fast and reliable internet connection all the time with large data capacity, an external power supply and lots of resource to provide stable website.
For all of those requirements, there are web hosting providers, where we can purchase packages from them, depending on our website capacity, type and usage etc. If our website have big traffic, big data usage, and/or large process, we can use dedicated hosting service and for a small website we can use shared web hosting service. Dedicated hosting service costs higher amount than shared, because if gives more specialised service. www.bluehost.com, www.godaddy.com, www.000webs.com are some famous hosting providers in the industry.
Assume that we bought hosting service from www.bluehost.com, then they will provide us some space(depending on the hosting package we select from them.) to store our website and give some addresses called, “nameservers”.
Now lets keep this in a side and look about the domain.
As we know, we need an address(name) for our website. www.google.com, www.ucd.ie are some of names that are taken for the websites. Domain names can be purchased from its own service providers like www.godaddy.com, www.onlydomains.com and also country specialised domains can be purchase from local authorised agency.(for Sri Lanka, its www.nic.lk) When we purchase the domain name from authorised agency, they will take responsibility on the domain and ask for name servers. At this moment, we have to input nameservers which we got from hosting service provider and after configuring it, a user will be able to reach the website we made and hosted.(It takes about first 24 hours to 100% configure redirection settings.)
This is the basic what we have to do to host a website. Now take a inner look how it works. The following diagram will be useful to understand the inner theory easily.
Click on Pic to enlarge. Pic from : https://pagely.c.presscdn.com/wp-content/uploads/2014/10/how-dns-works-wm.png
IP addresses are at the base of this process. Humans are natural creatures who can easily remember names, but not numbers. But, in web hosting and internet, numbers are the backbone. So this is why Domain Name Servers become essential. When we type an address in our browser address bar, it will lookup itself and it fails, then send a request to the closest domain name server and the server look for the ip address for the request. This server remembers recent and frequent ip addresses requests and if the server don’t have the desired ip address, then it will send the request to the next level / root level server to get the ip address.
Then the root level domain name servers redirects the request to the top level domain name servers. Root level domain name servers can identify where the request should goto by using requested domain extension and finally the request goes to the right place which can provide the ip address of the desired web domain. When the user (client computer) gets the ip address, then it calls the ip address and loads the site. What really happens is the IP address the user gets is the IP addresses of the given nameservers.
There are lots of DNS records in the servers. Some are mentioned below.
1. A records - IPv4 Addresses
2.AAAA records - IPv6 Addresses
3.AFSDB records - Location of database server
4.APL records - Address prefix List
5.CNAME records - Canonical name records
6.DS records - Delegation signer
7.KX records - Key exchanger records
8.NS records - Name server records
9.SIG record - Signature
10.TXT record - Text record
This is the surface and mid level inner side look on DNS and how it helps users to reach desired website. This service is long one, but takes milliseconds to provide the service.
Hope you got some idea about what is DNS and how it works. Comment your ideas and share with friends. :)
0 comments:
Post a Comment
Give your Comments and Guidance