What is a DNS server ?

all the web pages are hosted on a Web server, this webserver have their own IP addressees
DNS => translates the request of one webpage ex: www.google.com to the IP address of the webserver where the page is hosted.
this allows us to keep typing names on the web browser and not number(ip address)
*think of the phone book when you are searching by name

1) when we request to visit a page the browser will look at the local dns cache of the browser or of the operating system otherwise will sens a request to the resolver server (ISP provider)
2) if the resolver don’t find the matching request will send the request to the root server. 13 root server all over the wolrd managed by 12 organizations.
3) root server doesn’t have the corresponding IP address but knows which Top Level Domain (TLD) server to contact in order to obtain it.
4) TLD doesn’t know the IP either but will forward the request to the authoritative Name Server (NS)
5) Authoritative Name server has the IP and forwards it to the resolver server
6) Resolver server will answer our request and will cache that information so if the next time we will ask this information he doesn’t need to go through all the steps

Host => Resolver server (ISP) => root DNS server => Authoritative Name Server => Resolver Server (ISP) + cache => Host

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