CCNA 1 and 2 Companion Guide, Revised (Cisco Networking Academy Program) part 5 pps

PC Basics 9
Figure 1-3 Motherboard
■ Read-only memory (ROM)—A type of computer memory in which data has
been prerecorded. After data has been written onto a ROM chip, it cannot be
removed and can only be read. A version of ROM known as EEPROM (electron-
ically erasable programmable read-only memory) can be written to. It is called
Flash memory or firmware. The basic input/output system (BIOS) in most PCs is
stored in EEPROM.
■ Expansion slot—An opening in a computer, usually on the motherboard, where
an expansion card can be inserted to add new capabilities to the computer (see
Figure 1-4).
■ System unit—The main component of the PC system. It includes the case, chassis,
power supply, microprocessor, main memory, bus, expansion cards, disk drives
(floppy, CD hard disk, and so on), and ports. The system unit does not include
the keyboard, the monitor, or any other external devices connected to the computer.
■ Power supply—Supplies power to a computer.
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10 Chapter 1: Introduction to Networking
Figure 1-4 Expansion Slot
Motherboard Components
The motherboard is the computer’s main circuit board. It is crucial because it is the
nerve center of the computer system. Everything else in the system plugs into it, is con-
trolled by it, and depends on it to communicate with other devices in the system. The
following list describes the motherboard’s various components:
■ Backplane—A large circuit board that contains sockets for expansion cards.
■ Memory chips—RAM chips on memory cards plug into the motherboard.
■ Network interface card (NIC)—A printed circuit board that provides network
communication capabilities to and from a PC. Many newer desktop and laptop
computers have an Ethernet NIC built into the motherboard.
■ Video card—A board that plugs into a PC to give it display capabilities. Video
cards typically include onboard microprocessors and additional memory to

speed up and enhance graphics display.
■ Sound card—An expansion board that handles all sound functions.
■ Parallel port—An interface that can transfer more than 1 bit at a time. It is used
to connect external devices, such as printers.
■ Serial port—An interface used for serial communication in which only 1 bit is
transmitted at a time. The serial port can connect to an external modem, plotter,
or serial printer. It can also be used to connect to networking devices such as
routers and switches as a console connection.
■ Mouse port—Connects a mouse to a PC.
■ Keyboard port—Connects a keyboard to a PC.
N
O
TE
Some computers have
a network card,
sound card, video
card, and other cards
integrated into the
motherboard.
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PC Basics 11
■ Power cord—Connects an electrical device to an electrical outlet to provide
power to the device.
■ Universal Serial Bus (USB) port—This interface lets peripheral devices such as
mice, modems, keyboards, scanners, and printers be plugged in and unplugged
without resetting the system. USB ports eventually might replace serial and paral-
lel ports.
Desktop Versus Laptop
Laptop and notebook computers are becoming increasingly popular. The main differ-
ence between desktop PCs and laptops, other than the fact that laptop components are

smaller than those found in a PC, is that laptops offer more mobility and portability
than desktop PCs. The expansion slots are called Personal Computer Memory Card
International Association (PCMCIA) card slots or PC card slots in laptop computers.
The PC card slots are where devices such as NICs, modems, hard drives, and other
useful devices (usually the size of a thick credit card) are connected. Figure 1-5 shows
a PC card adapter for a wireless local-area network (WLAN).
Figure 1-5 PC Card
Lab Activity PC Hardware
This lab helps you become familiar with the basic peripheral components of a
PC system and their connections, including network attachment. You examine
the internal PC configuration and identify major components. You also observe
the boot process for the Windows operating system and use the Control Panel
to find out information about the PC hardware.
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12 Chapter 1: Introduction to Networking
Network Interface Cards
As shown in Figure 1-6, a NIC is a printed circuit board that provides network com-
munication capabilities to and from a PC. Also called a LAN adapter, a NIC plugs into
a motherboard and provides a port for connecting to the network. The NIC consti-
tutes the computer interface with the LAN.
Figure 1-6 Network Interface Card
The NIC communicates with the network through a cable and with the computer via an
expansion slot. When a NIC is installed in a computer, it requires an interrupt request
(IRQ) for service from the CPU, as well as an input/output (I/O) address, a memory
space for the operating system (such as Linux or Windows), and drivers to perform its
function. An IRQ is a signal that informs a CPU that an event needing its attention has
occurred. An IRQ is sent over a hardware line to the microprocessor. An example of an
interrupt being issued is a key being pressed on the keyboard. The CPU must move the
character from the keyboard to RAM. An I/O address is a location in memory used to
enter data into or retrieve data from a computer using an auxiliary device.

When selecting a NIC for a network, consider the following:
■ Type of network—Different types of networks use different types of NICs. For
example, Ethernet NICs are designed for Ethernet LANs. Some other types of
networks include Token Ring and Fiber Distributed Data Interface (FDDI).
Ethernet is by far the most common.
■ Type of medium—The type of port or connector used by the NIC for network
connection is specific to the medium type, such as twisted-pair, coaxial, fiber-
optic, or wireless. Coaxial is becoming increasingly rare.
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PC Basics 13
■ Type of system bus—There are different types of system buses, such as PCI and
ISA. Because PCI slots are faster than ISA slots, the latter are being phased out.
NIC and Modem Installation
Connectivity to the Internet requires an adapter card, which might be a modem or NIC.
A modem is an electronic device that is used for computer communications through
telephone lines. It allows data transfer between one computer and another over the
Public Switched Telephone Network (PSTN). Figure 1-7 shows an example of an
external modem. Typically, modems send data in blocks of bytes. After each block,
basic math is performed to analyze the block, and the computer on the receiving end is
asked whether it agrees with the results. If any differences appear, the block is sent
again. The modems convert digital data to analog signals for transmission over the
PSTN and then convert analog signals back to digital data on the receiving end.
Figure 1-7 External Modem
The term modem derives from the function of this device. The process of converting
digital signals to analog and back again is called modulation/demodulation (hence the
term modem). Modems can be installed internally or attached to the computer via a
serial or USB interface externally. Modems connect a computer to the network by dial-
ing the telephone number of another computer’s modem, typically that of the Internet
service provider (ISP).
The NIC lets hosts connect to the network. The NIC is considered a key component.

NICs are available in different types, depending on the individual device configuration.
Notebook computers can have a built-in interface or use a PCMCIA card. Desktop
systems can use a built-in or adapter card-type NIC.
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14 Chapter 1: Introduction to Networking
Situations that require NIC installation include the following:
■ Adding a NIC to a PC that does not already have one
■ Replacing a bad or damaged NIC
■ Upgrading from a 10-megabits per second (Mbps) NIC to a 10/100-Mbps NIC
To install a NIC, as shown in Figure 1-8, you need the following resources:
■ Knowledge of how the adapter is configured, including jumpers and plug-and-play
software. Most modern NICs do not require jumpers and are plug-and-play,
requiring little or no configuration. They can be configured using software that
comes with the NIC if necessary.
■ Use of network card diagnostics, including the vendor-supplied diagnostics and
loopback test (see the card’s documentation).
■ The ability to resolve hardware resource conflicts, including IRQ, I/O base
address, and direct memory address (DMA), which is used to transfer data from
RAM to a device without going through the CPU.
Figure 1-8 Installing a NIC
Overview of High-Speed and Dialup Connectivity
In the early 1960s, modems were introduced to provide data communications connec-
tivity for dumb terminals to a centrally based computer. Many companies rented com-
puter time because owning an onsite system was cost-prohibitive. The connection rate
was very slow—300 bits per second (bps), which translates to about 30 characters per
second.
As PCs became affordable in the 1970s, Bulletin Board Systems (BBSs) appeared,
allowing users to connect and post or read messages on a discussion board. Running at
300 bps was acceptable, because this exceeds the speed at which most people can read
or type. BBSs did not become widely used until the early 1980s, and the transfer of

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Testing Connectivity with Ping 15
files and graphics began to be desirable. The 300 bps speed quickly became intolerable,
and modem speeds started to increase. By the 1990s, modems were running at 9600
bps. They reached the current standard of 56 kbps (56,000 bps) by 1998.
Inevitably, the high-speed services used in the corporate environment, such as digital
subscriber line (DSL) and cable modem access, migrated to the consumer market.
These services no longer required expensive equipment or a second phone line. They
are also always-on services and therefore provide instant access that does not require a
connection to be established for each session. This results in greater reliability and flex-
ibility. It has also led to the ease of Internet connection sharing and small office and
home networks.
TCP/IP Configuration
TCP/IP is a set of protocols or rules developed to allow cooperating computers to
share resources across a network. A computer must be running the TCP/IP protocol
suite to access the Internet. To enable TCP/IP on the workstation, it must be config-
ured using the operating system tools. The PC requires an IP address, subnet mask,
default gateway, DNS (domain name server) information. These can be assigned man-
ually or obtained from a Dynamic Host Configuration Protocol (DHCP) server. The
information necessary to configure TCP/IP on a computer is typically obtained from
a network administrator or an ISP. The process is similar whether you’re using a
Windows or Apple Macintosh operating system. TCP/IP, DHCP, and DNS are covered
in subsequent chapters.
Testing Connectivity with Ping
Ping is a program that is useful for verifying a successful TCP/IP installation. It is named
after the sonar operation used to locate and determine the distance to an underwater
object. Ping stands for Packet Internet Groper.
The ping command works by sending multiple IP packets to a specified destination.
Each packet sent is a request for a reply. The output response for a ping contains the
success ratio and round-trip time to the destination. From this information, you can

Lab Activity PC TCP/IP Network Settings
This lab introduces you to the methods of discovering your computer’s net-
work connection, host name, MAC (Layer 2) address, and network (Layer 3)
address.
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16 Chapter 1: Introduction to Networking
determine if there is connectivity to a destination. The ping command is used to test
the NIC transmit/receive function, the TCP/IP configuration, and network connectivity.
The following are some usages of the ping command:
■ ping 127.0.0.1 (internal loopback test)—This verifies the operation of the TCP/IP
stack and NIC transmit/receive function. Figure 1-9 shows the ping 127.0.0.1 test.
■ ping IP address of host computer—Verifies the TCP/IP address configuration for
the local host.
■ ping default-gateway IP address—Verifies whether the router that connects the
local network to other networks can be accessed.
■ ping remote destination IP address—Verifies connectivity to a remote host.
Figure 1-9 ping 127.0.0.1
Web Browsers and Plug-Ins
A web browser acts on a user’s behalf by
■ Contacting a web server
■ Requesting information
■ Receiving information
■ Displaying the results on the screen
Lab Activity Using ping and tracert
In this lab, you learn to use the TCP/IP ping and traceroute commands to test
connectivity in a network. In the process, you see name resolution occur.
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Web Browsers and Plug-Ins 17
A web browser is software that interprets Hypertext Markup Language (HTML), one
of the languages used to code web page content. Other markup languages, such as

SGML and XML, provide more advanced features for creating dynamic and interac-
tive web pages than does HTML. HTML, the most common markup language, can
display graphics and play sound, movies, and other multimedia files. Hyperlinks are
computer program commands that point to other HTML files on a web server or other
places in the same documents, which provide shortcuts to other web pages and files.
Two of the most popular web browsers are Internet Explorer (IE) and Netscape. Although
they are identical in the task they perform, there are differences between them. Some
websites might not support the use of one or the other, so it can be beneficial to have
both programs installed on the computer.
Table 1-1 compares the characteristics of these two web browsers.
Standard web browsers cannot display many special, or proprietary, file types. To view
these files, the browser must be configured to use plug-in applications. These applica-
tions work in conjunction with the browser to launch the program required to view
the special files. Here are some of the more popular proprietary plug-ins:
■ Flash Player/Shockwave Player—A plug-in that plays multimedia files created by
Macromedia Flash.
■ Adobe Acrobat Reader—A software program that allows the user to view and
print Adobe Portable Document Format (PDF) files.
■ Windows Media Player—A software program that allows the user to play audio
and video files.
■ Quicktime—A software program created by Apple that allows the user to play
video and audio files.
■ Real Player—A software program that allows the user to play audio files.
Table 1-1 Microsoft Internet Explorer Versus Netscape Communicator
IE Communicator
Integrated with other Microsoft products First popular browser
Takes up more disk space Takes up less disk space
Displays HTML files and performs e-mail,
file transfers, and other functions
Displays HTML files and performs

e-mail, file transfers, and other
functions
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18 Chapter 1: Introduction to Networking
Other Common Computer Applications
Computers perform many other useful tasks. In business, employees regularly use a set
of applications that come in the form of an office suite, such as Microsoft Office or
Lotus Smart Suite. Office applications typically include the following:
■ Spreadsheet software—An application that lets users construct spreadsheets
consisting of columns and rows. It is often used with formulas to process and
analyze data.
■ A word processor—An application that lets users create and edit text documents.
Modern word processors allow the user to create sophisticated documents that
include graphics and richly formatted text.
■ Database software—An application that lets users store, maintain, organize, sort,
and filter records. A record is a collection of information identified by a common
theme, such as a customer name.
■ Presentation software—An application that lets users design and develop presen-
tations to deliver at meetings, classes, or sales presentations.
■ Personal information managers—Applications that can include features such as
e-mail, contact lists, a calendar, and a to-do list.
Binary Numbers
This section introduces the way in which data is represented inside a computer and the
form in which it is transmitted across a network. You also learn about the various
number systems and logic used with computers.
Lab Activity Web Browser Basics
In this lab, you learn how to use a web browser to access Internet sites, become
familiar with the concept of a URL, and use a search engine to locate informa-
tion on the Internet. You access selected websites to learn the definitions of net-
working terms and use hyperlinks to jump from the current website to other

websites.
Lab Activity The Basic PC/Network Troubleshooting Process
In this lab, you apply the basic troubleshooting model to simple and common
network problems. You also become familiar with the more common hard-
ware and software problems.
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