The Internet: IP Addresses, URLs, ISPs, DNS & ARPANET

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  • 0:11 Internet Basics and History
  • 2:19 Internet Protocol (IP) Address
  • 3:26 Internet Service…
  • 3:55 Communication (TCP/IP)…
  • 5:49 Internet Corporation…
  • 6:09 How We Access Specific…
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Lesson Transcript
Instructor: Jill Heaney

Jill has taught college-level business and IT. She has a Doctorate in Business Administration and an M.S. in Information Technology & Leadership.

We'll cover the basics of the Internet, including its history and functioning. Key topics include IP addresses, TCP/IP communication protocol, DNS, URLs, and the transfer of information as packets through the Internet.

What is the Internet?

Wendy: Hi, Grandma!

Grandma: Hi, Wendy! It's so nice of you to drop by for a visit. What have you been up to these days?

Wendy: Well, I just finished writing a research paper for my business ethics class.

Grandma: You must have spent hours at the library researching all of the information that you needed.

Wendy: Actually, Grandma, I was able to conduct all of my research on the Internet from my dorm room.

Grandma: Really?! I hear so much about the Internet but I really don't understand what it is, how it works or who even came up with the whole idea. It all baffles me. I hear the term 'Internet' used frequently but what does it really mean?

Wendy: The Internet is a worldwide system of computers and networks linked together. These computers and networks, which are scattered across the globe, vary in shape and size. They cooperate with each other in order to exchange data through a wide variety of network technologies. Words, images, sound files and software can all be transmitted through the Internet via the telephone system, copper wires, cables, optical fibers or radio waves. What is most unique about the Internet is that no one owns it and there is no formal managing organization.

Linked ARPANET institutions in 1969

History of the Internet

Grandma: So who created the Internet?

Wendy: The Internet began as a project for the Department of Defense in 1962. ARPA, or the Advanced Research Projects Agency, was responsible for designing a computer network for military use. The goal was to ensure functionality even if connections between computers were severed. The idea was to create a network that could send and receive transmissions through different data paths rather than just one. This network was called ARPANET.

When it was completed in 1969, the network linked the University of California at Los Angeles, the Stanford Research Institute, the University of California at Santa Barbara and the University of Utah. More and more networks were added to ARPANET. By 1981, another network was developed for colleges that were not able to access ARPANET. This nationwide network was called National Science Foundation Network or NSFNET.

By the early 1990's many networks were leaving ARPANET for NSFNET due to the enhanced speed. NSFNET became known as the Internet.

Internet Protocol (IP) Address

Grandma: Wow, the Internet has quite a history. I never would have guessed it. So, how does the Internet work? It seems so mysterious given the way information from all over the world can be accessed.

Wendy: Yes, Grandma, it does seem mysterious, but there is a logical explanation for the functioning of the Internet. Since the Internet is comprised of a global network of computers, there must be a way to identify each computer and device connected. That's where Internet Protocol (or IP) comes in. Everything connected to the Internet has an IP address. That includes computers, servers, cell phones and any other equipment.

Each computer within the global network has a unique IP address
IP Address

All of these have a unique IP address in order to connect to the Internet. The IP address allows each computer connected to the Internet to be identified. The IP address is like your home address. If someone wants to send you a letter, they need to know your full address. The IP address will take the form of four sets of numbers. Each number must be between 0 and 255. For example, is a sample of an IP address.

Internet Service Provider

Grandma: I see, that makes sense.

Wendy: In order to connect to the Internet, your computer is routed through the Internet Service Provider or ISP. An ISP is a company that provides access to the Internet. Examples of common ISPs are Comcast, Verizon, AT&T, EarthLink and Time Warner Cable - among many others.

Grandma: Okay, I'm familiar with many of those companies. In fact, my telephone service is through Verizon.

Wendy: Exactly; those companies not only provide telephone service, but Internet service too.

Communication (TCP/IP)

Wendy: Once your computer connects to the Internet it must be able to communicate with other computers and devices. Computer networks have rules for communication known as protocols. They are necessary for proper communication to take place.

TCP/IP or Transmission Control Protocol/Internet Protocol is a communication protocol suite that is particularly important for the Internet to function. Simply put, it establishes rules for how information passes through the Internet. When you want to send and receive information over the Internet, the TCP/IP protocol suite is what makes it possible.

Domain Name System (DNS)

The components of a URL
URL Example

Wendy: The Domain Name System or DNS is a distributed database comprised of all the websites on the Internet and their corresponding IP addresses. Think of the DNS as a telephone book. Each geographic area has a phone book in which you can look up the telephone number and address of a person based on their name.

No one DNS server contains the entire database. A distributed database means that portions of the database are divided and spread to many different servers on the Internet. If a DNS server does not contain the domain name requested, it will redirect the request to another server.

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