Internet & the Web Flashcards
Understand the mechanics behinds how the internet works
How does the internet work?
Please explain the full process of how the internet operates.
- Two computers, directly connected, can communicate.
- Information in the form of light pulses are divided into small chunks, known as packets.
- The computer sends these packets through the router (internal network), and are forwarded to the modem (information manageable by the telephone infrastructure)
- The modem carries the information from our ISP (internet service provider) through the network of ISP networks to the destination network (this is carried from our home telephone network to the Optical Fibre Network)
- The browser/computer sends a request to the DNS server to get the destination network’s IP address
- The internet retrieves IP addresses corresponding to our domain name request via DNS, the Domain Name System
- After getting the IP address, your browser forwards the request the respective server and its corresponding data center
- Once the server gets a request to access a particular website, the data flow starts
- The data is transferred in the form of **light pulses **via optical fiber cables, which run underground and underwater, across the globe.
- These light pulses sometimes have to travel thousands of miles via the optical fiber cable to reach their destination (optical fiber cables are always beneath the ground)
- Upon reaching your phone, the **packets are assembled **according to their **sequence **number.
What is a web server?
A computer that hosts a website on the Internet.
What is a network?
A network consists of two or more computers that are linked in order to share resources (i.e. printers), exchange files, or allow electronic communications.
The computers on a network may be linked through cables, telephone lines, radio waves, satellites, or infrared light beams.
What is the internet?
Please explain in 1-2 sentences.
At its most basic, the Internet is a large network of computers which communicate all together.
The Internet is the backbone of the Web, the technical infrastructure that makes the Web possible.
What is an IP address?
If you want to send a message to a computer, you have to specify which one.
Thus any computer linked to a network has a unique address that identifies it, called an “IP address” (where IP stands for Internet Protocol).
It’s an address made of a series of four numbers separated by dots, for example: 192.0.2.172.
What is a router?
A router is a tiny computer which serves as a hub which “routes” internet traffic between connected devices and the internet on an individual network
This router has only one job: it makes sure that a message sent from a given computer arrives at the right destination computer (like a signaller at a railway station)
To send a message to computer B, computer A must send the message to the router, which in turn forwards the message to computer B and makes sure the message is not delivered to computer C.
Example:
- Without a router, 10 computers communicating with each other would require 45 cables, with nine plugs per computer
- Once we add a router to the system, our network of 10 computers only requires 10 cables: a single plug for each computer and a router with 10 plugs.
How does an ISP work?
The internet consists of a network of cables connecting the globe, including copper telephone wires, TV cables, and fiber optic cables.
ISPs not only provide entities with access to the internet, but they also maintain the infrastructure that makes it possible.
An internet service provider takes the data you are requesting through the internet and sends it to a server that has that information through these cables.
To receive internet from an internet service provider, an individual must enroll in that provider’s service, usually through a subscription. Individuals will create an account and pay a monthly rate for their internet service provider to supply them with any equipment they may need and the bandwidth to access the internet.
When one subscribes and connects to an internet service provider, they join their network that interconnects with networks across the globe. The internet allows one to access almost any information they need and communicate with those worldwide.
What are packets and how are they used to transfer data?
A packet, or network packet, is a formatted chunk of data sent over a network.
Packets exist due to the fact that sending the entire sum of data in one go, down one route, will likely mean that it will get stuck in traffic and take ages.
So, the video is torn apart, broken apart, split into packets.
Each one makes its own way back down different routes and when they start arriving back at your device, they’re juggled into the right order. This is how information spreads across the world.
What is a client?
Computers connected to the internet are called clients and servers.
Clients include:
- Internet-connected devices
(I.e. Your computer connected to your Wi-Fi, or your phone connected to your mobile network)
- Web-accessing software available on those devices
(Usually a web browser like Firefox or Chrome)
What is a server?
Servers are computers that store web pages, sites, or apps.
When a client device wants to access a web page, a copy of the web page is
downloaded from the server onto the client machine to be displayed in the user’s web browser.
What is a web page?
A web page is a simple document displayable by a browser.
Such documents are written in the HTML language (which we look into in more detail in other articles).
A web page can embed a variety of different types of resources such as:
-> Style information: Controlling a page’s look-and-feel
-> Scripts: Add interactivity to the page
-> Media: images, sounds, and videos.
Web pages can each be found at a unique location (IP / URL).
What is a web browser?
A browser is a piece of software that retrieves and displays web pages;
I.e. Firefox, Google Chrome, Opera, Microsoft Edge, or Apple Safari.
What is a search engine?
In the analogy of a library, what mechanic is the search engine similar to?
A search engine is a special kind of website that helps users find web pages from other websites.
I.e. Google, Bing, Yahoo, or DuckDuckGo.
Search engines are normally accessed through a web browser’s address bar, or, through a search engine’s web page.
What is a DNS request?
DNS is used to translate an actual name into a string of numbers known as IP addresses.
What are the steps involved in a DNS lookup?
- Browser and O/S determine if they know that that IP address already in your computer’s cache
- If both the browser and O/S do not know where “www.example.com” is, the operating system is configured to ask a resolving name server, for IP addresses it does not know.
- This resolving name server is the workhorse of the DNS lookup and know where to find the root name servers
- The root name servers will reply with “I don’t know, But I do know where to find the com name servers. Try there.”
- The resolving name server then takes all of this information from the root name servers, puts it in its cache, and then goes directly to the COM TLD name servers.
- When the resolving name server queries www.example.com, the TLD name servers respond, “I don’t know, but I do know where to find the “Example.com” name servers. Try there.” (The TLD name servers know this information through the domain’s registrar. When a domain is purchased, the registrar is told which authoritative name servers that domain should use. They notify the organization responsible for the top level domain (the registry), and tell them to update the TLD name servers.)
- The resolving name server takes the response from the TLD name server, stores it in cache, and then queries the (http://example.com/) name servers. At this point, the authoritative name server will say, “Hey! I know where that is! Tell your browser to go to the IP Address 192.168.1.1!
- The resolving name server takes this information from the authoritative name server, puts it in cache, and gives the reply to the operating system.
- The operating system then gives this to the browser. The browser then makes a connection to the IP address requesting the web page for (http://www.example.com/).
Describe the process that takes place when you initiate a search through a search engine, i.e. via google.com
The process that takes place when a search is initiated via search engine such as google.com:
- The search engine checks its index for web pages which it has discovered via web calming and indexing
- When a search query is performed, all pages deemed relevant from the index are identified and ranked hierarchically via an algorithm in order of relevancy.
- In addition to the search query, search engines utilize relevant data to return results, including location, language detected, previous search history, device of user.
What are the responsibilities of an ISP?
- Providing and maintaining the essential equipment and infrastructure to access the internet
- Ensuring transfer of data through the internet is safe
- Routing internet traffic
- Provides subscribers with a certain bandwidth amount and internet speed
- An ISP should protect its subscribers from cyber threats and warn them if they are at risk.
- Internet Service Providers should work together with one another if there is a threat, danger, or emergency that could harm providers.
- Internet Service Providers also have an unwritten duty to prevent criminal activity on their networks.
In the analogy of a library, please describe:
What element of the web is similar to a library building?
The library is like a web server. It has several sections, which is similar to a web server hosting multiple websites.
In the analogy of a library, please describe:
What element of the web is the sections of the library similar to?
The different sections (science, math, history, etc.) in the library are like websites. Each section is like a unique website (two sections do not contain the same books).
In the analogy of a library, please describe:
What element of the web are the books in a library similar to?
The books in each section are like web pages.
One website may have several web pages, e.g., the Science section (the website) will have books on heat, sound, thermodynamics, statics, etc. (the web pages).
Web pages can each be found at a unique location (URL).
In the analogy of a library, please describe:
What is the search index at a library similar to on the web?
The search index is like the search engine. Each book has its own unique location in the library (two books cannot be kept at the same place) which is specified by the catalogue number.
What is a web site?
A website is a collection of linked web pages (plus their associated resources) that share a unique domain name.
Each web page of a given website provides explicit links—most of the time in the form of clickable portions of text—that allow the user to move from one page of the website to another.
What is a modem?
Modem stands for “ modular-demodulator”
Modems are devices that turn digital information into analog sound signals for the telephone journey and then turn it back again at the other end.
Think of modems as translators. Computers speak digital, and telephones speak analog, so you need modems to translate between the two.
A modem is a device connecting your home to your internet service provider (ISP) through a physical connection.
The modem modulates digital signals sent from the user’s computer via adding them on top of an analog telephone signal)
Once the signals have reached the other end, they have to pass through a second modem, which demodulates them (separates them out from the telephone signal and turns them back into digital form) so the ISP computer can understand them.
When the ISP computer replies, it sends its signals through a modulator back down the line to you.
Then a demodulator at your end turns the signals back into digital form that your computer can understand.
