Hi there mate, First, I am very much thankful you keep my blogs alive even though I’ve been silent for almost more than two months. The reason is that I already took the exam and yup, I am now Nicole Guzman, CCNA. Anyway, I am very thankful to those followers and those who are requesting for me to write a blog post for me to share my knowledge and at the same time learn as I teach here. We will be dealing this time on DNS lookup operation as a special topic requested.
So can you imagine a world wherein you use IP address instead of the name of website each time you visit internet? Can you imagine teaching your grandma accessing internet by the use of IP address instead the website itself? Definitely, it is not user-friendly. So DNS came as a solution for that.
DNS lookup operation works like this:
1st Our goal is for PC1 to get to http://www.halimbawa.com
2nd Your browser or operating system will determine whether he already knows this website. It is either configured on the operating system, or stored on cache. For demonstation reasons, let us take the worst case scenario.
3rd In the event your browser or operating system doesn’t know the website, it will ask the resoving name server whether it is stored on cache.
4th In the event that the resolving name server cannot find the IP address of such website,it will inquire Root name server.These servers are really special, because they hold all of the domain names and their corresponding IP addresses
5th In the event that the resolving name server cannot find the IP address on root name server, root name server would refer it to the TLD name server. TLD refers to the top level domain. For example, on the website http://www.halimbawa.com, com is the TLD.
6th TLD name server would lastly refer resolving name server to go to AUTHORITATIVE NAME SERVER. How did TLD server know that the IP address of http://www.halimbawa.com can be found on Authoritative name server? First, ANS or authoritative name server is on top of the hierarchy of DNS servers. Also, when such domain was bought ,the domain registry will notify the organization responsible for the TLD (registry) and tell them to update the TLD name servers
Lastly, the resolving name server already knows the IP address of http://www.halimbawa.com and it is 192.168.33.5. Hola! PC1 can now get to http://www.halimbawa.com. It may seem very complex but the thing here, it is the most overlooked process.