What happens when we type http://www.google.com

pradeepvu · New Member Joined: Dec 28, 2009 Posts: 16 Location: India

What happens when we type http://www.google.com. Can anyone please provide me the step by step process.

Chris · Posted: Mon May 24, 2010 1:24 pm Post subject:

Pradeepvu,

In a very compact step-by-step, here's the procedure. Let's assume you typed: www.cisco.com:

1) Your PC will need to resolve www.cisco.com to an IP address. It will therefore need to send a query to your DNS server ( usually your ISP's DNS).

2) The Pc constructs a DNS query packet with a destination IP address equal to your DNS server and a destination MAC address of your router (gateway).

3) The DNS query process begins. This is explained in much detail on our DNS page: http://www.firewall.cx/dns-resolution.php

4) Once your PC (web browser application) receives the IP address of the destination web server, it will construct a HTTP GET request and send it to Cisco's web server.

5) Cisco's Web server will reply and start sending your application the necessary data using TCP sessions. These sessions are again explained in great detail in our TCP protocol analysis: http://www.firewall.cx/tcp-quick-overview.php

6) The application will start to draw and present the website on your screen.

Of course, between all the above data exchanges, the packets that run in your local network have their destination and source mac addresses set to the relevant local machines (your pc and router).

Hope that helps!

Cheers.
_________________
Chris Partsenidis.
Founder & Senior Editor
http://www.firewall.cx

KiLLaBeE · Posted: Tue May 25, 2010 1:51 am Post subject:

Just whatever you do, don't type google into Google...you can break the Internet Razz

Source:
http://www.youtube.com/watch?v=5oCHxB8d20s

Chris · Posted: Tue May 25, 2010 2:29 am Post subject:

KiLLaBeE - hahaha good one mate !!!! 50 points to KiLLaBeE!
_________________
Chris Partsenidis.
Founder & Senior Editor
http://www.firewall.cx

Nevins · Enthusiastic Member Joined: Jan 26, 2010 Posts: 217

Chris,

I agree with everything you said so I'm just going to copy it and add to it.

In a very compact step-by-step, here's the procedure. Let's assume you typed: www.cisco.com:

1) Your PC will need to resolve www.cisco.com to an IP address. It will therefore check need to your computers local host file and if it doesn't find the IP address (which it generally does not unless you put it there) it will send a query to your DNS server ( usually your ISP's DNS).

Your host file can be located at: C:\winnt\system32\drivers\etc
if you are on a windows system. It looks like this:

After checking the host file and finding nothing USER enabled DNS settings will be checked. If none are found it defaults to your ISP'S DNS service.

2) The Pc constructs a DNS query packet with a destination IP address equal to your DNS server and a destination MAC address of your router (gateway).

3) The DNS query process begins. This is explained in much detail on our DNS page: http://www.firewall.cx/dns-resolution.php

4) Once your PC (web browser application) receives the IP address of the destination web server, it will construct a HTTP GET request and send it to Cisco's web server.

5) Cisco's Web server will reply and start sending your application the necessary data using TCP sessions. These sessions are again explained in great detail in our TCP protocol analysis: http://www.firewall.cx/tcp-quick-overview.php

6) The application will start to draw and present the website on your screen.

Of course, between all the above data exchanges, the packets that run in your local network have their destination and source mac addresses set to the relevant local machines (your pc and router).

shwetashree · New Member Joined: Jun 27, 2010 Posts: 1

This is really helpful but can anyone tell me what exactly happens in transport and network layer when GET request is sent

JamieP · Occasional Member Joined: Jun 04, 2010 Posts: 54

the same as when any other packet is sent, the network and transport layer really dont care what TCP packet type or HTTP requests they are sending, its all payload to them.

best tip if you want to see how packetflows work is download wireshark, and look at the packets, a bit of playing and you can get it to follow TCP conversations, and see all you syns and acks etc...