Understanding how all networking layers work together -


i'm trying understand how networking layers i.e. physical layer, datalink layer, transport layer, application layer work together. know how work individually not clear how work together.

the current understanding have follows:- when type url, fetching , sending of data done according http, ftp protocols highest layer. there layer divides data data sequences tcp , udp protocols come play. there layer deals routing of data i.e. algorithm reach source destination without error , there physical layer.

i have studied various sources fail tell me how combines together. executed web browser? done os? done machine? these questions not answered. more precise:-

1) program converts clicking of button http request? browser?

2) program converts http request tcp/udp headers? os it? os understand tcp/udp?

3) program decides how data reach machine server? decides path follow?

4) program converts tcp/udp headers 0s , 1s , physical layer?

  1. the browser starts process. when enter web address in browser (or click link), browser creates tcp socket used send http request. create tcp socket, device needs know ip address of domain name entered (lets www.stackoverflow.com). if browser not have ip address of stackoverflow in cache nor os, operating system creates dns query message ip address.
  2. the tcp protocol implemented in operating system.
  3. the route packet follow determined on network layer (layer 3). routers layer 3 devices. device sends packet destination ip default gateway router (if destination not in local network). device not know route packet follow, nor interested in that. use analogy of post office, when write letter write source address , destination address , put in letterbox. don't know nor interested how letter destination. job of post office determine. router use routing algoritms determine appropriate path. router communicate between each other , send necesary information each router can calculate best route every destination address. result of process routing table, means each router knows particular network destination, should forward packet got on port 1 port 2 , not port 3 or 4 (for example). every router on path makes decision.
  4. the network interface card in end translates datalink segments 0s , 1s

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