AP Computer Science Principles Unit 2

The Internet of Things

Physical Network

Able to Physically connect devices to one another so that information can move through the network.

It works by Fiber optic cables, wifi signals, or copper wires physically connect the computers, smart phones, servers, etc. that make up the Internet. Computers don’t need to be directly connected to each other, just a single point on the network.

IP: Internet Protocol

Works by uniquely identifying people on the internet and routing messages between them.

It works by setting each device on an internet with a uniquely given IP address. Packets sent on the internet include to and from IP addresses. Routers along the way use this information to move data along a path of direct connections. Routing happens dynamically, meaning the path is unpredictable and changes based on network conditions.

TCP: Transmission Control Protocol

Works by Sending large messages over the Internet when accuracy is most important. You would either use TCP or UDP.

It works by sending divided messages into packets and sending it all at once. Packets are numbered so that they can be re-ordered and missing packets can be requested by the receiver. TCP is slower than UDP because error checking like this takes more time, but it is much more reliable.

UDP: User Datagram Protocol

Able to send large data over the Internet when speed is most important. You would either use TCP or UDP.

Works by dividing messages into packets and sending all at once. There is no error-checking to ensure all packets arrive or that they’re in order. UDP is faster than TCP but more errors are possible. This is useful for streaming video or online gaming because having the picture displayed quickly is more important than it being displayed with a clear picture.

DNS: Domain Name System

Able to translate human-readable domains like websites like example .com into IP addresses that the Internet can use.

Works When you try to go to a domain like example .com, your computer first contacts a system of servers collectively called the DNS which keeps track of the IP addresses associated with each domain name. Communication with DNS servers happens over the Internet, meaning the requests to and from servers are sent as TCP/ IP packets.

HTTP: HyperText Transfer Protocol

Able to Allow computers to request and share webpages, audio, images, videos, and other file types on the Internet, collectively known as the world wide web

Works with computer communication in plain text like GET to request files or send data. The server that receives the request responds with the files requested which are displayed by your browser. HTTP requests are sent between computers over the internet as part of TCP/IP packets. The world wide web is just files that are requested using HTTP and sent over the Internet.

How do the Internet Layers Form?

HTTP+DNS= TCP / UDP —> IP —> Physical Network

What are Packets

splitting, sent information into smaller chunks of data in order to reduce the file size so that it can reach the destination cleaner.

Instead of transferring a huge file as a single data block, sending it in smaller packets improves transmission rates and also enable multiple computers to share the same connection.