How DNS Works?

DNS- (domain name service ):

The Internet's system for converting alphabetic names into numeric IP addresses. For example, when a Web address (URL) is typed into a browser, DNSservers return the IP address of the Web server associated with that name.

->DNS uses UDP.-(Because as DNS need to be fast TCP is not prefered as TCP has a large                               overhead).

->DNS servers bind to UDP port no 53.



HOW IT WORKS❓❓❓❓

Terms you should know:
  1. Resolving Name Server.
  2. Root Server
  3. TLD Server.
  4. Authoritative Name Server.


⇨What happens if open your browser and fire up www.example.com.❓

⇨First of all brrowser checks it cache for information about example.com if it finds any info about the IP address of example.com then it retrives the html content of example.com  .If not then,

⇨browser asks Operating system wether it knows anything about example.com Operating System checks it cache for any entries of example.com if it finds something it will return the answer otherwise Operating system knows who to ask. It is "Resolving name server".

⇨The resolver server is usually your ISP (Internet Service Provider). All resolvers must know one thing: where to locate the root server.

⇨—Root servers will direct you to TLD NAME SERVER(Top level domain name servers. thai is .com servers) [all the info for redirection to TLD NAME SERVERS is put into cache of resolving name server].


—TLD servers will redirect you to ATUHORITATIVE NAME SERVERS(These servers has the info for example.com)

¢BUT HOW DOES TLD KNOW ABOUT AUTHORITATIVE NAME SERVERS???
¢WHILE PURCHASING DOMAIN NAME REGISTRARS UPDATE TLD NAME SERVERS
¢All the info about example .com is gathered from authoritative name servers and put it into the cache of resolving name server.
¢Finally resolving name server gives the info to our Operating System.




Check out awesome resource for DNS:https://howdns.works/

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