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02-internet.md

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Internet

Websites on the Internet

How do they work?

https://projects.propublica.org/graphics/images/data-institute/presentations/how-websites-work.pdf

Internet Basics

https://developer.mozilla.org/en-US/docs/Learn/Common_questions/How_does_the_Internet_work

  • Internet - a network of networks
  • "World Wide Web" - a service built on top of the internet's infrastructure (other services include e-mail and IRC chat, neither of which use HTTP)
    • HTML - Hypertext Markup Language
    • HTTP - Hypertext Transfer Protocol

DNS Lookup

Source: Mozilla Developer Network

#c5f015 Example

There are lots of programs that can resolve a domain name for you, one of those is dig (domain information groper).

dig google.com +short

Routing

Data travels sent over the internet is chopped up and sent in packets. Here is what an IP packet looks like. It has a header which contains the metadata and a payload which contains the data. Different protocols handle packets differently. For example, some protocols like those you might use to stream video will tolerate packet loss, other protocols like TCP/IP which is used to transmit websites don't).

Routers route those packets to their correct destinations based on the metadata the packet carries.

https://en.wikibooks.org/wiki/A-level_Computing/AQA/Computer_Components,_The_Stored_Program_Concept_and_the_Internet/Structure_of_the_Internet/Packet_switching

Here is a strange videos:

#c5f015 Example

You can use traceroute to see how your request is routed to its destination.

traceroute google.com

The Internet has Layers

Source: Wikimedia Commons

If you're really interested:

And if you're not: