NET 101 - Networking Essentials I

Chapter 2, The Internet

Objectives:

This lesson discusses some history, features, and uses of the Internet. Objectives important to this lesson:

  1. Evolution of the Internet
  2. Broadband connections
  3. IP addresses and domains
  4. Browsers
  5. Searching the web
  6. More on social networking
  7. Examples of types of web sites
  8. Publishing on the web
  9. Examples of features and services on the Internet
  10. Netiquette
Concepts:

The chapter begins by reminding us that the Internet is a collection of networks of various kinds. It was created in 1969 as a project of the Advanced Research Projects Agency (ARPA), which was part of the U.S. Department of Defense. The text states two goals of the project:

  • to allow scientists at different locations to communicate and work together
  • to continue to work even if part of the network was down

The legends about the reasons for the project refer to the Cold War and American fears of Soviet dominance. The reality is that there were only a handful of computers capable of doing large scale research computation, and ARPA wanted to make them accessible to researchers at more institutions.

The network was called the ARPANET when it was created.

  • When it was first turned on (1969), the ARPANET connected computer networks at only four locations: UCLA, Stanford University, UC Santa Barbara, and the University of Utah. When the first message was sent on it, the connection failed before the first word was completely sent. Things got better.
  • Skipping ahead fifteen years (1984), there were about a thousand computers on the network. Note that the book calls them hosts. The book incorrectly says that a host is a server. A host is simply a computer that is a member of a network. Servers are hosts, but so are all other devices on the network.
  • Skip ahead ten more years (1994), and I will tell you that there was much public discussion about the Internet, as it was called. A big question at the time was whether to allow commerce on the Internet. Think about that: people were arguing about whether to allow anyone to sell things on the Internet.
  • It is probably impossible to count the number of devices on the Internet, partly because that number varies from moment to moment. The book suggests the number of users is in the billions, and the number of servers in the millions.

The book asks who owns the Internet. The answer is complicated, because many parts are owned or managed by many entities. Different rules about its use vary from one country to another, but general rules and standards are written by an international committee the World Wide Web Consortium (W3C). Although their mission is mainly the web, that is big enough that they are seen as a central authority for things like the structure and use of web pages.

In general, all methods of connecting to a network can be classed as either wired or wireless.

  • wired - may use any of several types of physical cable, including twisted pairs of copper wire, coaxial cable, or fiber optic cable
  • wireless - the text says that "a computer without a communications device can use a wireless modem" to connect to a network. Well, maybe, but this passage leads you to believe that that is the only thing needed. That's not clear, and not very true.

A device needs some way to connect and to communicate to be on a network.

  • Most computers you can buy today will have a standard network interface card (NIC) either installed already or built in on their main circuit board (motherboard).
  • Devices like tablets and smartphones typically rely on Wi-Fi connections to connect to a wireless access point (WAP) which is a device that is itself connected to a network by normal means, and which allows devices to connect to that network through it. (There is more to this, especially with regard to security. More on that later.)

On page 57, the text provides some examples of wired and wireless connection methods.

  • wired - Internet service from a cable tv provider is a good example.
  • wired - DSL, digital subscriber line, which is provided by a telephone service company
  • wired - FTTP, fiber to the premises, which means you are connected by a fiber optic cable, and could be provided by either type of provider above
  • wireless - Wi-Fi, wireless fidelity, which we discussed last time as being available in many stores and restaurants; may be a primary or secondary way to connect to a network, primary at McDonalds for customers, but secondary for devices in my home
  • wireless - Mobile broadband - often implemented as a plug-in card for a laptop that connects to a cellular service provider's data network, this also describes the use of broadband data service with a smartphone through the cellular provider
  • wireless - Fixed wireless - Most individuals will not use this technology directly, but may use it without realizing it. Think of data being transmitted from an antenna on a tower to another antenna on another tower. This is done when there is no easy way to run a wire, such as across a river or a lake, or in a city where there are no accessible data channels.
  • wireless - satellite Internet service, for locations too far away for DSL and no local cable system, a dish antenna system must be installed and aimed at a satellite owned or leased by the service provider

As you can see from the examples above, the words wired and wireless each include multiple technologies, so knowing only that about a given system is not enough information to understand how it works. In this section, the text also discusses using a wireless modem, and gives the impression that it is a magical device to connect to cell data service. This is the same thing as the mobile broadband method listed above, and it is not magic. First, if you are not in an area where you have cellular data service, forget using it. Second, if you do not have a large data plan with your provider, use it sparingly or look for huge cell phone bills.

The author must have considered cost at this point, since the discussion moves on to Internet Service Providers (ISPs), and access plans. When they say plan, think contract and level of service. The text mentions that plans can be compared based on services, bandwidth, and speed, Guess what? Bandwidth and speed are the same thing. Electrons move across a wire at a constant speed. The question is how many of them are moving to you at once. That is bandwidth, and it is a measure of how long it will take to move a file of any size across the Internet to you.

The text is correct in explaining that a character, a letter or a number on a screen, fills about one byte. If you haven't heard, a byte is a basic unit of memory and of file size, partly because if what it can hold. Standard metric prefixes are used for larger units of memory and file space.

  • kilobyte (KB) - a thousand bytes
  • megabyte (MB)- a million bytes
  • gigabyte (MB) - a billion bytes

For the purists who know better, the units listed above are rounded off. Some people use these definitions, while others use more accurate definitions. A kilobyte is supposed to be 1024 bytes, but some vendors use the rounded figures to appear to give you more. In addition, bandwidth is traditionally measured in bits per second, not bytes. There are eight bits in a byte. So, if I told you your bandwidth was 8 Mbps, that means 8 Megabits per second, which means only 1 Megabyte per second, 1 MBps.

The text does a good job (figure 2-4) of displaying a simplified route from a home user to a cable switch box, to a central facility, to the Internet backbone, to the network where a requested resource exists. On the return trip to the requester, data may pass through different paths, but eventually gets back to the user in less time than it takes to explain it. In some cases, there may be no need to leave the system the user starts on: at Baker, your route may go very quickly to a server on the same network as your workstation, to open the Baker home page. On the other hand, your request may have to be sent to the opposite side of the world for the requested web page or document.

The text moves on to mention IP addresses. Let me try to fill in some of the gaps:

IP stands for Internet Protocol, which is one of the indispensable protocols (programs that use a set of rules on a network) that make the Internet work. The purpose of an IP address is to identify each unique node on a network. On an IP network, each device (node) is known as a host, and every host must have an address. The addresses we discuss first are actually IP version 4 addresses. (IPv6 addresses will be 16 bytes, or 128 bits long.)

IP version 4 addresses are numeric addresses, stored as four bytes, which is equal to 32 bits. For example: an IP v.4 address might be 10.45.17.122. Each of the four numbers is held on one byte.

Since the IP protocol was invented with networking in mind, IP addresses contain two parts: one part of the address identifies the network a host is on, and the other part identifies the host itself. Every network is assigned an address which could take up one, two, or three bytes, depending on the class of the network (A, B, or C). The remaining byte or bytes are typically used for hosts on networks. (It gets more complex: this is how we start.)

There are five address classes you need to know. The first three classes can be described by the number of bytes assigned to the network portion of their addresses:

  • one byte identifies a class A network
  • two bytes identify a class B network
  • three bytes identify a class C network

Class D and E addresses use portions of the fourth byte as well for network addressing. You may wish to know that only class A, B, and C addresses are for general use. Class D addresses are for multicasting (messages to groups of machines), and class E addresses are for experimental use.

This is more than your book tells you, and it is only the beginning of the story. We should hit more on it in a later class.

The book also mentions that only geeks and nerds use addresses on the web. Most people prefer to use domain names when looking for a something on the Internet. The information needed to find a host on the Internet is too complex and too fluid to remember. Devices can be given new addresses for several reasons, so knowing yesterday's address may not work. When the Internet became too large for any single file to hold all the information (yes, that's how it worked in 1969), a new system was needed, so DNS was invented. Domain Name Service (DNS), also called Domain Name System, uses a hierarchy, a tree shaped structure that branches as you go down the tree.

  • The DNS tree starts at what is called the root-level domain.
  • All root-level domain servers know how to get to all top-level domain servers, the next layer down. Top-level domain servers are the authorities of their domains, like .com, .net, and .org, as well as .ca, .au, .ch, and all the other top-level domains. Servers at this level can be called primary or master servers.
  • In its domain, each top-level server knows the addresses of each second-level domain server, such as microsoft.com. These are the registered domain servers. Registered domains can include subdomains, so they are included in this level as well.

These are several top-level domains:

com Commercial entities
edu Educational institutions
gov Agencies of the U.S. Federal government
mil US Military
net Computers of network providers
org Miscellaneous: for organizations that do not fit anywhere else
biz Businesses. This is essentially an alternative to .com
name Personal URLs. A person can apply for a subdomain for their own name.
pro Professional organizations.
au Australia
ca Canada
de Germany (Deutschland)
uk United Kingdom

Most countries have two letter domain names. Some, like Germany, are not intuitive until you remember what the country is called in the primary language spoken there.

The text moves quickly to obtaining a domain name. You can contact your ISP first, or you can shop around on the web to see who has a good price. Many registrars exist who can help you. A larger concern is where you might want to house your web pages. I decided to register my domain name through Yahoo, partly because the price was competitive, and partly because they let me write my web pages myself and upload them, as opposed to having to use some software of theirs that I might not like.

Domain names have existed for some time, which can mean that the one you would like to have is already taken by someone else. If it is in use by someone else, you usually have no choice: you must choose another name. On the other hand, if it is being held by a cybersquatter, someone who registered it in the hope of selling it for a high price, you could sue to get access to the name. It is less expensive to move on. This link takes you to a legal reference site that will provide more background.

The text briefly describes domain name resolution, the process in which you enter a domain name in a browser, it consults the DNS system, and the system replies with an IP address that the browser actually uses to access the web site. If that is so, then what was I talking about when I said you could get to Baker's web pages faster? The Internet is built from routers, devices that find a path to a resource. There are routers on Baker's network (and every network). These local routers would know about a resource on their own networks and would be able to connect to such a resource quickly, without having to ask routers on any other network for the information.

This takes us back to the World Wide Web. The text mentions that web pages may be static or dynamic. An example of a dynamic page is iGoogle, which is due to be shut down in a few weeks (it is presently early October, 2013). Google has provided this page as a free service to anyone interested in customizing a web page to include news, weather, blogs, and many other things. Google is shutting down the service this November. Is this a sign that dynamic pages are not successful? Maybe it is more a sign that a vendor makes more money by controlling a large part of what appears on a web page, customizing it for the viewer if there is a point to do so, like showing the viewer an ad for a service they are known to have shown interest in. On the other hand, Yahoo has a similar service called My Yahoo, which they seem to be continuing. Trying to pull over some users?

The text reintroduces browsers, and repeats some information from chapter one about web pages and servers. The term "home page" is mentioned, and we are warned that it has two meanings. This is true of many computer related concepts: people love to make up a new definition for something that already has two or three good ones already. So, today's word is home page:

  • the page that a browser is configured to open when the browser starts; users can typically set their own browser for any page they like
  • the main page of a web site, typically the page you get when you enter the domain name of a site in your browser's address line

Both definitions are correct, so you need to tell what someone means by the context in which such a term is used. Get used to it, you will run into this kind of thing a lot.

Page 62 (does your book match mine?) has a section at the bottom about safe browsing. You should consider some of these techniques to avoid problems.

  • http stands for Hypertext Transfer Protocol, which was invented for web pages. It works fine, but you should never consider sending sensitive information to a page unless it is using https, Secure Hypertext Transfer Protocol. And before we go to far, no, that is not enough. There is more, but we don't want to wear you out. Look over this article for a short list of safety hints.
  • phishing is a technique of sending an email that contains a web address that "looks" real, but is not, and actually leads the user to a malware site or a site that collects information from the user to steal money from them. First defense: READ the screen. If you hover over a link, your browser often tells you the address the link goes to. Have you trusted the links I have given you, or have you looked at them first? Why?
  • block pop-ups and use an up to date anti-virus program. I have followed links in news stories recently that would have led me to malware sites if my anti-virus protection software had not stopped and warned me.

Whether you use a tablet, a laptop, a desktop, or a smartphone, you should pay attention to what you are doing to avoid trouble. Different devices often change what browsers you can use. If you are in doubt, put the phone down, and use a better protected device.

The text explains that there is a difference between domain names and full addresses. An address is also called a URL, a Uniform Resource Locator, and it contains more information. Let me illustrate:

  • My domain name is stevevincent.info, which only specifies the top level domain, info, and the domain I registered.
  • The URL to my web site is http://stevevincent.info, which also includes the protocol that is used to access the site. In my case, it is not necessary to put www in front of my domain label. (Each phrase in an address that precedes or follows a period is a label.)
  • If I were providing an address to take you directly to this page, it would be http://stevevincent.info/NET101_2013_2.htm, which includes a forward slash after the name of the top level domain, and the name of this file.

    Web addresses use forward slashes as breaks between folders because most web servers in the olden days ran on UNIX, and UNIX uses that kind of slash as a folder/directory marker. The tradition has been followed ever since. (Windows systems use backslashes, except for web addresses, where they follow the UNIX standard.)

The text continues with background that would be most useful to someone who has never seen the web before. I find it hard to remember not knowing what a search engine was. I have yet to find a use for social networking. I will call your attention to the Secure IT feature at the top of page 70, listing some privacy and security risks associated with social networking sites.

Assignment: read the Secure IT section on page 70, and write a short response to each of the two questions at the end of it. This can be done as a group assignment, provided that you represent the opinions of everyone in the group.

Assignment: Browse the material from pages 67 through 79. Tell me about two of the services listed that you could (or could not) make personal use of. Briefly describe how the service does or does not relate to your life. This is an individual assignment.

The text continues with a discussion of common features found on web pages, such as:

  • graphics, color bars, and photos
  • animation of various sorts
  • audio to enhance stories or the user experience
  • video: news sites, YouTube, educational sites, and every other type

Page 84 begins a discussion of email and related products, which leads into the topic of Communication. When you send an email or an instant message, and when you start a chat session, you typically know who your audience is.

This is different from putting up a web site, writing a blog, or typing your thoughts in a discussion forum. In these cases, you do not know who will be reading what you send out into the network. In fact, you don't know that about the email, messages, or chats either, because sending a signal out to the net is like any kind of publishing: you can't affect what happens to anything once it leaves your control.

That being the case, you should consider the advice on page 90 about Netiquette, a silly word that means Internet or network etiquette. Some thoughts are just conventions:

  • ALL CAPS mean you are shouting. Really? Did you automatically imagine those words louder? It only means something because enough people have agreed that it does.
  • Use emoticons to express emotion. No, children, not everywhere. This has no place in business communication, or other formal communication. Use emoticons for informal communication, or not at all. The same goes for the abbreviations listed on page 90.

Some of the other ideas are for your protection and that of others:

  • Be polite. Things come back to haunt you.
  • Don't be abusive or insulting.
  • Be careful what you write. I was told by an English teacher many years ago that I should never write down something that I would not want an enemy to read. I am pretty sure Mr. Pawloski would have the same opinion of what we send out on the Internet.