Com Sci Assessment Unit 2
Pick the 2 statements that are true about the Internet Protocol (IP)
! Each device or computer on the Internet is assigned a unique IP address. x IP is a secret protocol shared between the sender and receiver. x Each network on the Internet uses its own protocol to address messages. x In order to communicate two devices on the Internet must have the same IP address. ! IP is the shared way that all devices and computers label their messages with the sender and receiver's addresses.
What is a GET request and what are you requesting?
'GET (name of the documents you're requesting)' in the HTTP
How does the DNS help the internet scale?
- 1 DNS server cannot handle all the requests from all devices - DNS servers are connected in a distributed hierarchy, and are divided into zones, splitting up responsibility for the major domains such as .org, .com, .net, etc.
What do certificate authorities do and why are they necessary?
- are trusted entities that verify the identities of websites and issue certificates for them - ensures that you are connecting to the real website - if website tries to start connection w 'janky certificate' your browser will warn you
What problem is HTTP solving?
- the language used to communicate between browsers and servers - the language that a computer uses to ask another computer for a document
HTML (hypertext markup language)
--> language used to tell a web browser how to make a page look - <strong> (bold) - <font> - <A> (link to other pages) - < IMG ALIGN = "middle"> (image alignment) * images and videos have unique URLS that aren't included in the HTML; browser sends separate http request, displays them as they arrive
Packet -- made of 1s and 0s
A chunk of data sent over a network. Larger messages are divided into packets that may arrive at the destination in order, out-of-order, or not at all.
Router
A type of computer that forwards data across a network
What are the benefits of building redundancy into a network? What are the potential issues with building redundancy?
Building redundancy into a network allows the system to be fault tolerant. Even if individual components fail, the information may take an alternative path so it can still reach the intended recipient. Redundancy can become an issue when information takes longer, less efficient paths to reach a destination. The network would run slower than it could.
Fault Tolerant
Can continue to function even in the event of individual component failures. This is important because elements of complex systems like a computer network fail at unexpected times, often in groups.
Packet metadata
Data added to packets to help route them through the network and reassemble the original message
UDP (User Datagram Protocol)
Definition: A protocol for sending packets quickly with minimal error-checking and no resending of dropped packets Main Idea: Like clearing out the library as fast as you can. The goal is to send information quickly without worrying about accuracy. Basics of how it works: Send all the packets but don't check if they all get through or arrive in the correct order Use in real life: useful when split seconds matter more than correcting errors like video-conferencing, live streaming, online gaming
TCP (Transmission Control Protocol)
Definition: a protocol for sending packets that does error-checking to ensure all packets are received and properly ordered Main Idea: Like numbering every book in the library. It's slower but more accurate Basics of how it works: Number packets so they can be re-ordered, confirm all were received, resend any missing packets. Multiple back and forth confirmations between sender and receiver. Use in real life: Useful when accuracy matters more than saving a split second, like sending emails, photos, or just browsing websites
DNS
Domain Name System
HTTP
Hypertext Transfer Protocol - manage the sending and receiving of web files with DNS
Datastream
Information passed through the internet in packets
If the internet were made of direct, dedicated connections, it would be impossible to keep things working as millions of users join. Especially since there's no guarantee that every wire is working in the computer at all times.
Instead, data travels on the Internet in a much less direct fashion.
ISP
Internet Service Provider
How does HTTP rely on other layers of the Internet?
REFER TO ACTIVITY GUIDE
Why are SSL, TLS, and HTTPS necessary?
Secure Socket Layer, Transport layer security --> layers of security wrapped around your communications to prevent hackers from seeing your info: active when you see the lock in your web browser address bar next to the https Hyper Text Transfer Protocol Secure --> ensure that your HTTP requests are secure and protected
World Wide Web vs. Internet
The World Wide Web are files, web pages, and media. The Internet is the network we use to access those files.
Describe how the Internet Protocol (IP) allows devices to easily connect and communicate on the Internet.
Under the Internet Protocol, every device on the network is assigned a unique numerical address and communicates using the same protocol. Using the IP, different devices can exchange information by sending a message and origin address to another IP address. In return, the device that received the message can send information back. This is essentially how the Internet works. When someone looks up a website, the corresponding address to the site is retrieved.
DNS spoofing
When a hacker taps into a DNS server and changes it, to match a domain name with the wrong IP address; sends people to an imposter website
Example of TCP: requesting a song from Spotify
When you request a song on your device, Spotify sends the song as many packets. When your packets arrive, TCP does a full inventory & sends back acknowledgements of each packet received. If all packets are there, TCP signs for your delivery and you're done! If TCP finds packets are missing, it won't sign because you're song won't sound as good or have missing parts. For each missing or incomplete packet, Spotify will resend the packet. When TCP verifies that all packets are there, the song will play.
The internet is . . .
a design philosophy and an architecture expressed in a set of protocols
Computing System
a group of computing devices and programs working together for a common purpose
Computing network
a group of interconnected computing devices capable of sending or receiving data
Computing device
a machine that can run a program, including computers, tablets, servers, routers, and smart sensors
Hypertext Transfer Protocol (HTTP)
a protocol for computers to request and share the pages that make up the world wide web on the Internet
Internet Protocol (IP)
a protocol for sending data across the Internet that assigns unique numbers (IP address) to each connected device
World Wide Web
a system of linked pages, programs, and files
Cookie data
an ID card for site, a number that identifies you web browser holds onto that number, ID number is sent with request now tumblr server sees request and knows its from David
protocol
an agreed-upon set of rules that specify the behavior of some system
Packets travel like cars;
depending on "traffic conditions & congestion" packets may be forced to take different routes -- can change midway through the conversation
Large images or pieces of information may be sent in several different packets that all take different paths
each packet has the Internet address of where it came from and where it's going
HTTP post request
information is sent to web server ('cat videos', survey info) in plain text using HTTP post request Web page & invisible cookie data is sent back for web browser to save --> website can remember who you are
Internet
made up a large number of independently operated networks; information is distributed a communication system that could survive an attack
TCP (Transmission Control Protocol)
manages the sending and receiving of all your data as packets
Information from one computer to another travels in what we call a ____________ of information.
packet
Special computers on the internet called ______________ act like traffic managers to keep the packets moving through the networks smoothly.
packets may arrive at the destination at slightly different times or even out of order
Because of the principles of fault tolerance and redundancy, the more routers we add, the more . . .
reliable the internet becomes
TCP and router systems are __________
scalable
The DNS and IP are designed to . . .
scale
How does the DNS solve the problem of translating domain names like example.com into IP addresses?
the DNS associates names like www.example.com with the corresponding addresses. Your computer uses the DNS to look up domain names and get the associated IP address, which is used to connect your computer to its destination on the internet.
Scalability
the capacity for the system to change size and scale to meet new demands
redundancy
the inclusion of extra components so that a system can continue to work even if individual components fail, for example by having more than one path between any 2 connected devices in a network
bandwidth
the maximum amount of data that can be sent in a fixed amount of time, usually measured in bits per second
Path
the series of connections between computing devices on a network starting with a sender and ending with a receiver
The Domain Name System (DNS)
the system responsible for translating domain names like example.com into IP addresses - an important system in helping the internet scale
IP address (Internet Protocol address)
unique number (like a street address) that's unique to each device on the network
Which of the following is true regarding the way information is transmitted on the Internet?
x Information flows on a dedicated direct connection from the sender's device to the receiver's device using binary electrical signals. x If a single packet is dropped, the entire file must be resent. x Because of the reliability of the Internet, packets always arrive in the same order they were sent. ! Information does not travel in one piece, but rather as a datastream of packets.
Pick Two: If the post office delivered mail exactly like the routers deliver messages on the Internet, which of the following statements would be true?
x One mailman would be responsible for delivering a letter from sender to receiver ! The mailman would sometimes take a different path to deliver each letter to your home ! Letters would be written on the outside of the envelope for all to read instead of letters put inside envelopes x Your mail could not be delivered if a road your mailman was planning to take were under construction.
Visiting a website is just . . .
your computer asking another computer for information. Your computer sends a message to the other computer's IP address and also sends it's origin address so the other computer knows where to send it's response.
