NET 101 - Networking Essentials I
Chapter 4, Programs and Apps
This lesson discusses programs and applications, categories
that classify them, and features found in most items in major
categories. Objectives important to this lesson:
- Program and application definitions
- Major software categories
- Operating systems
- Software categorized by cost and availability
- Productivity software features
- Graphics and media software features
- Communications software
- Security software
- File and disk management
Concepts related to Student Learning Objectives
- Bandwidth types
- Cable characteristics
Despite the heading for this section, programs and applications (apps) are not
necessarily different things. There are many kinds of programs. In
general, they are all sets of instructions that tell devices what to do. Often, a program does
not tell a device how to do
something. Instead, it relies on another program to do that.
An example: I might be using Microsoft
Word to write a document, and I want to save it.
- Word is an application,
because it is a particular kind of program. It is for word processing.
(Hence its name.) Word can save files, as all word processors should,
but technically, it does not know how to do that.
- When I tell it to save a file, Word passes the request to
the operating system of the
computer I am using. In my case, and in the case of the computers in
our classroom, the operating system is Windows
7. An application generally passes requests to read and write
files, to use a computer's display, to access storage media, and use
any hardware connected to the computer to the running operating system.
- This information is repeated in the large graphic on page
As you might imagine, an operating
system is not one program, but a
collection of them. It is not an application, because it does not do
the specific, specialized things an application does. It does, however,
services to other programs that are applications.
Consider the table on page 153. It lists several categories that a
program might belong to, and several subcategories within each group.
When you are shopping for a program/application to meet a particular
need, it helps to know what kind of program it is, so you can research
reviews and ratings for programs of that type.
The text lists some operating systems on page 154. Note that
the versions that run on smart devices
may be different from "similar" versions that run on laptops and desktops. In all cases, an operating
system is loaded into memory
when the device is turned on,
and a user interface is
presented, which is used to start applications.
There is a pretty strange bullet list on page 154. It blends
two concepts: software that is for
sale or free (to some degree), and
software that runs on the device or
the web. Let's break that up a
Software by cost:
- freeware - software
that can belongs to someone (or some
organization) but anyone can have a copy at no charge, usually by
downloading it from a web site. An example is the 7Zip
utility program. 7Zip will take large files and compress them so they take up less
space. It will also decompress
such files so they can be used. The text points out that the "free" in
freeware means there is no charge for it. As opposed to what, that it
lives in a non-totalitarian country?
- open source software
- software that is not just free, but that a programmer is free to
change and improve, then share the changes back to a group of users
(usually the original programmers) who decide whether to include the
improvements in the next version. In a sense, this is crowd-developed
- shareware -
software that you can try out for a while (or maybe you can try out
some of its features for as long as you like), but you have to pay for
it eventually if you want to continue using it (or to access the rest
of its features). This kind of software is usually a download, and
usually priced lower than retail software.
- retail software -
software from a publisher, typically written for a mass market
audience, and typically available through stores of all kinds and as
downloadable software. Some software of this type comes in bundles,
like Adobe's Creative Suite, which has been available as four different
combinations of their products.
- public domain software
- sometimes a publisher decides that a program just won't sell any
longer, and it may make sense to make that program available to users
for free; The Electronic Arts
company makes some of its games available for free through their Origin
game download and management web service. I suspect that they restrict
the downloads to their site only for two reasons: it keeps the games
clean (uninfected), and it brings users to their site who may see
something they want to buy
Software by how it runs:
- installed app - the software must be installed
on the device in order to use it
- web app - the software runs through a
browser window, so a user must access a web address to use it and prove
they are allowed to do so; remember that you need connectivity to use it
- installed mobile app - like the installed
app above, but with less overhead; typically a smaller set of functions
are presented in a simplified user interface, so it runs better
(faster, or at all) on a smart device
- mobile web app -
like the web app above, but with less overhead; typically a smaller set
of functions are presented in a simplified user interface, so it runs
better (faster, or at all) on a smart device; remember that you need
connectivity to use it
The text mentions license
Most software, during its installation process or when it is first
used, will present a long, boring, complicated legal agreement to the user in a
window on the user's display. The only thing the typical user wants to
do at that moment is to use
the program, so most people breeze past this step saying that they agree
to whatever the publisher wants, clicking whatever button is required
to get on with it. It is worth knowing that even if you do not read
these agreements, you are bound
by them, and you are responsible for actions that violate the
agreement. Feel more like reading one now?
The text warns us that there are web sites that will offer
software for download that may turn out to be pirated, infected, or
worthless. Most of us want to avoid such problems, so we should
consider the advice on page 157 about this subject. How do you
determine that a site is safe to take a download from? How do you tell
that a web site is reputable? In searching for a driver for a printer
this week, I found a site that looked like it belonged to a printer
vendor, and found that it was instead a front for a vendor of an
automatic update product that would "provide better service once I
purchased the full version". I deleted the ridiculous thing and scanned
the computer for viruses.
The text continues on page 157 with a discussion of common features found
in several kinds of Productivity
Applications. At this point, the chapter becomes a survey of
software types, to help the student become more familiar with many of
them. Review this section for any ideas you are not familiar with
already. The section discusses software made for several specific purposes:
- project management
- word processing
- database management
- note taking
- calendar and contact management
In addition to the types of programs listed above, there are
several more specialized types of software that are
often used by professionals and less often used by
non-professionals, because of the special training needed to understand
the data being collected and reporting required.
- accounting software
- tax software
- legal software
- enterprise management software
On page 170, the text moves on to Graphic and Media
applications. This category includes some very broad subcategories:
- Computer Aided Design (CAD)
- Desktop Publishing
- Image Creation/Editing
- Photo Editing
- Image Management
- Video and Audio Editing
- Multimedia Authoring
- Web site Authoring
The categories listed above are concerned with creating
art of one kind of another. The text includes two more types
in this section that are not really part of that concept:
There is a chart on page 171 of communications applications.
Note that they all require access to and use of a network.
Four aspects of security software are presented, all of which
are useful for users and professionals:
- firewalls - can be software or hardware that watches for
odd or threatening behavior on a network device, such as an attack from
outside your network or a virus inside it
- anti-virus software - needs to be updated often, and should
run at all times
- anti-spyware/adware - may be used to remove problem software
that is technically not virus software
- Internet filters - used to prevent access to questionable
sites and known malware locations
In addition, note the Secure IT discussion
on page 181 about virus hoaxes.
The last section of this chapter concerns what we might call
examples of utility software. There is no common
theme to the examples, other than their not fitting very well in the
- file managers
- search tools
- image viewers
- uninstall tools
- disk cleanup tools
- defrag tools
- screen savers
- file compression tools
- backup and restore tools
We will discuss these briefly in class.
Since the book is not covering several topics that we are
supposed to cover, let's look at a few facts about cabling.
Networks are often discussed in terms of models, like the ISO Model, which breaks the subject into layers, topics, and methods. The bandwidth topic can be split into two methods for
using the bandwidth of a medium. It relates directly to cabling.
- Baseband - this method uses the entire bandwidth
of the medium to send one signal at a time. This means one transmitter
at a time, so users have to take turns or contend for access.
- Broadband - this method uses separate channels in
a medium, such as frequencies, to send multiple signals simultaneously.
Users have little need to wait for access in this kind of system.
Computers use electric currents and various forms of electromagnetic
waves to communicate. We can class networks as being cabled
(wired) or wireless, for obvious reasons. We should consider
five attributes for each type of medium to make a good choice:
- Cost - which media cost more or less than others
- Ease of installation - how easy is it to set up
- Capacity - also called bandwidth, this
means how much data can be on the net at once
- Attenuation - When a signal passes along a medium,
it tends to fade (attenuate) over distance. We compare media to see
which ones have better (longer) attenuation rates.
- Immunity from EMI and RFI - Electromagnetic
Interference happens when your medium picks up static
or bad data you don't want. Radio Frequency Interference
means that you are getting the interference from an actual radio signal
source, not just from stray static electricity. Media that are
susceptible to EMI and RFI are also susceptible to eavesdropping (also
called signal capture).
There have been several types of cable
media used in networks over the years. (Follow the link to a
Microsoft TechNet article about media. It is not perfect, but it is
- twisted pair - has been used in two types:
- unshielded - UTP does not have an EMI
- shielded - STP has an EMI resistant
sheath, which can be foil or braided metal
- coaxial - Coax similar to that used for
cable TV, and now used by cable providers for network access as well
- fiber optic - glass or plastic channels that
conduct light, often red laser light
Short physics lesson: In a copper wire, electrons don't actually flow from
one end of the wire to the other. What happens is more like the
movement of a large ripple or wave in
water. Imagine a wave moving toward a shore in a lake or an ocean. Do
specific water molecules make the whole trip? No. The energy of the
wave is passed across a series of molecules. The energy
passes across the medium. For the purists among you, I will note that
the speed of electromagnetic waves through the electrical media varies
with the nature of the conductor. It can be over 90% of c
in a UTP wire, and a bit slower in coax. What's c? The speed of light in a vacuum.
The graphic shown here illustrates several twisted pairs of
wires. Each wire is covered with an insulator, and the two wires in
each pair are meant to be used as a circuit. These wires suffer from crosstalk,
leakage of signal. The twists help cancel out such leaks. The graphic
shows a UTP cable with eight wires in it, making four pairs. As is
typical, there is a green pair, a blue pair, an orange pair, and a
brown pair. Other color schemes are used, but this one is common.
The wires in each pair are twisted around
each other. This type of cable comes in several varieties: two pair,
three pair and four pair were common, but four pair is the current
standard. Also, each variety may be available in grades, such as CAT 1
(Category 1, which is pretty useless on modern networks) and CAT 5
(Category 5, which has been a standard for several years). There are
several such categories, and a major difference between them is the
number of twists per foot in each pair. CAT 1 will have less than 5
twists per foot, CAT 5 will have 25 or more twists per foot (so it is
better, and costs more). Note that the better the class of cable, the
less leakage, and the more bits per second can be passed across it.
Connecting a system with
twisted pair wiring is easy. A possible problem is that the wiring
closets in any building are often in need of being "cleaned up". The
"closet", typically on each floor of a building, contains punch-down
blocks, patch panels, and hubs (or switches). Many are disorganized and
messy. People who try to clean them up, however, must be careful not to
disconnect circuits that are needed.
The factors for UTP:
- Cost - inexpensive
- Installation - cheap and easy
- Capacity - 1 to 100 Megabits per second (Mbps), but 10
Mbps is common in home networking. Gigabit throughput is
possible if the other network equipment (network cards, switches, routers) support it
- Attenuation - nothing is perfect, so this is high (poor)
- Immunity from EMI - also poor. Recommendation: run UTP
lines perpendicular to fluorescent lights to avoid a constant static
UTP cables are usually connected to devices with RJ-45
connectors. Your text does not show an RJ-45 connector (or any other)
very well. In the enlarged picture on the right, note the eight
gold-colored conntacts for the eight wires usually found in UTP
cables. The wires are used in pairs to form two to four circuits.
RJ-11 connectors are typically used for telephone
(Shielded Twisted Pair) cable is very similar
to a UTP cable, except that it has a metal foil sheath around each pair
of wires, or around the entire set of wires. When the sheath encloses
all the wires, it resembles the ground sheath in a coaxial cable, but its purpose is to shield the cable from interference..
This cable is more expensive than unshielded cable, and is
less flexible due to the stiff shielding. The shield, however, makes it
more EMI resistant than UTP.
The factors for STP:
- Cost - Moderately expensive
- Installation - harder than UTP, needs special connectors
(note the IBM-style Token Ring connector shown here)
- Capacity - 1 to 500 Megabits per second (Mbps) is
possible, but 16 Mbps is common (for Token Ring)
- Attenuation - high (poor)
- Immunity from EMI - also poor, but not as bad as UTP.
IBM Data connectors
were typically used with Shielded Twisted Pair cable on a Token Ring
Coaxial cable is called that because
it has two conductors, one wire in center and a conductive sheath
around it, that share a common axis, hence coax.
Most people have seen this style of cable used with cable television.
The wiring standards used for network coax have been
different from those used for cable TV. This is a list of cable used
through networking history:
- 50 ohm cable, available as RG-8 and RG-11.
Used in Thick Ethernet, also called "Ether Hose".
- 50 ohm cable, available as RG-58. Used in Thin
- 75 ohm cable, available as RG-59.
- 93 ohm cable, available as RG-62. Used in ARCnet.
The number associated with each RG specification tells you
the relative size of the central conductor. Smaller numbers
mean thicker wires.
- The coaxial line is essentially a single bus, going from
one station to the next.
- At each end of the line, the cable has to have a terminator
- At one end, it also has to be grounded.
- If using thin Ethernet, T-connectors
- If using thick Ethernet, vampire taps
are used. They are called vampire taps because little teeth bite into
the cable (to contact the shield), and a big tooth bites deeper to
contact the central conductor when you screw the clamp down.
The factors for Coax:
- Cost - Relatively low to Moderately expensive (depending
on thickness of the cable)
- Installation - simple to install, hard to modify
- Capacity - high rates are possible, but 10 Mbps is common
- Attenuation - high, but less than twisted pair
- Immunity from EMI - moderate
The example on the right shows a typical T-connector with BNC
fittings. The fitting on the bottom of the image
might attach to a port on a NIC that looks like the
barrel on either end of the top of the T. Attachment is achieved by
pushing the connector onto the barrel of the port, then twisting the
collar of the connector to lock onto the pin that is part of the port.
In other words, it mounts like a bayonet.
The next (enlarged) picture shows a BNC connector attached
to a thin Ethernet cable. Such a connector would be used to attach to
one of the T-connector barrels in the photo above. The other end of the
cable would run to the next node on the network.
optic can be glass or plastic, and is meant to conduct light
instead of electricity. The conductor is called a waveguide,
and is covered with cladding, a material to reflect the signal
back into the center of the conductor. Two configurations exist. Loose
configuration has a liquid filler between the outer sheath and the
conductor. Tight configuration has wire or stiff fibers around
the conductor to add strength to the cable.
Fiber optic comes in two modes: single mode conducts
a single signal, while multi-mode conducts many signals
simultaneously. You may want to know that the most common type
used is 62.5 micron core with 125 micron cladding, multimode.
The factors for fiber optic:
- Cost - Expensive, mostly for installation
- Installation - difficult
- Capacity - 100 Mbps at up to 20 kilometers per segment
- Attenuation - very low
- Immunity from EMI - immune. This is light, not