The scenes behind visit website :part I
Have you ever wondered that waht happens when you type an URL in the browser and visit a website
let’s say you have entered:https://aminalaabidi.medium.com/ Grammer in the browser
Browser first checks the cache for the DNS record to find the correspoding IP address of our URL.
For this, browseer performs the 4 levels of cache:
- browser cache
- Os cache
- Router cache
- ISP cache
What the heck in this DNS record?
In simple terms a DNS record is nothing but the pair which describes the particular URL and it’s associated IP adress
DNS (Domain Name System) is a database that maintains all these DNS records.
Okay ,but why there is a need of DNS?
Can’t we access website directly from IP address
Yes , you can, but it is not practially possible for us humans to remember each IP address of all the websites.That’s why DNS is used.
So the primary purpose of DNS is human-friendly navigation.
ok , so continuing to our example, if the browser finds the DNS record in any one of the cache then now it can simply initiate the request.
But if the browser does not find the cache in any of the cache level, then your ISP DNS Server initiates a DNS query to find the IP address of the server that hosts
https://aminalaabidi.medium.com
The pupose of a DNS query is to search multiple DNS servers on the internet until it finds the correct IP address for the website.
DNS Hierarchy
The under diagram is about how DNS hierarchy works and how DNS query is resolved ,if the request is successful, then it returns the IP address back to the browser.
