A+ Certification Guide

Chapter 16 (Part A)

Networking

Chapter 16 (Part A) Objectives

Network Models and Topologies

– The client/server and peer-to-peer networking models Internet Connectivity Technologies

– How to install and make dial-up connections. Services such as ISDN, DSL, cable, and satellite. LAN connectivity to the Internet.

Network Protocols

– Basics about Transmission Control Protocol/Internet Protocol (TCP/IP)

TCP/IP Applications and Technologies

– The protocols, services, and ports used by TCP/IP Network Tools

– Tools for cabling a network Network Types

– Wired and wireless network technologies

Network Models Client/Server:

– Servers provide services to clients.• Print server provides access to print device.• Web server provides access to html files.• Domain controller provides centralized security services.

– Ability to grow with organization.– Centralized security, auditing, and network management.

Peer to Peer:– Each workstation is independently managed.

• All security is contained on locally managed disk.– Limited growth due to lack of manageability.

• File can be shared, but each folder on each machine must be individually shared and controlled—time-consuming.

LANs and WANs

Local Area Network (LAN)– A group of computers and network-attached devices located in

the same building or at least on the same property

Wide Area Network (WAN)– WANs connect LANs to each other.– Distance between local networks generally distinguishes LANs

from WANs.– WANs typically lease the use of third-party wires/equipment

from a provider to make connections.• Data Communications Service Providers

– AT&T, Bellsouth, Sprint, and so on

Network Support Devices Hub Bridge/Switch Wireless Access Point Router Layer 3 Switch Firewall Network Attached Storage Modem Internet Appliance VOIP Phone Systems

Network Topologies Bus

– Computers in a bus topology share a common cable. Connections are made largely with coaxial 10BASE2 and 10BASE5 cables.

Star

– Computers in a star topology connect to a central switch (wired) or access point (wireless).

– Used by 10BASE-T, 100BASE-T, and 1000BASE-T Ethernet networks and by Wireless Ethernet when configured for infrastructure mode.

Ring

– Computers in a ring topology either connect as a physical ring (for example, FDDI networks) or a logical ring (for example, Token Ring networks).

Peer-to-Peer (Mesh)

– Computers in a peer-to-peer or mesh topology can connect directly to every other computer.

– Used by computers with multiple network adapters, Wireless Ethernet (Wi-Fi) when configured for peer-to-peer mode, and Bluetooth.

Internet Connectivity Technologies

Dial-up connectivity:– Modems– ISDN

Broadband DSL Satellite Cellular WiMAX Trunk lines (T-1)

Dial-Up Connections

Telephone Modems:– Uses analog telephone connection by converting digital serial

data into sound wave-based analogy data– Bandwidth (speed) limited to 56Kbps– Can be internal or external– Can be installed as PC Card on a notebook computer– Follow usual ESD precautions when installing

ISDN (Integrated Services Digital Network):– Also uses a modem and telephone line– Can transmit 128Kbps– Often used as backup line to a T-1 or faster connection

Broadband Internet Services (DSL, Cable, and Satellite)

Broadband Service:– Uses a cable modem to convert broadband signaling to baseband

signaling (serial)

– Generally associated with cable TV providers

– Shared media with other local customers

– Advertised bandwidth of 2-10Mbps

• Sometime less, sometimes more

DSL:– Dedicated bandwidth

– Dependent on distance from phone company for quality of service

Satellite:– Requires a telephone for transmitting service requests

– Uses a dish antenna precisely focused on a satellite

DSL Modem Physical Setup

DSL Modem and Single PC Topology

Cable Modem and Single PC

LANs and Internet Connectivity

Allows more than one device to access Internet via a single connection

– Requires• Internet access device

– Cable modem– DSL modem

• Router– Forwards data packets from the Internet to the

local network and vice versa– Can be a workstation set up with Internet

Connection Sharing (ICS)

LAN Connection to Internet

The ISP equipment could be a DSL, cable modem, or even a T-1 connection.

Network Protocols Transmission Control Protocol/Internet Protocol (TCP/IP)

– Dominant networking protocol in the world– Has been adopted by all manufacturers of networking devices

NetBIOS Extended User Interface (NetBEUI/NetBIOS)– No network number in its structure

• Cannot be routed on an internetwork• Useful only on a single broadcast domain

TCP/IP is the only practical protocol to know– Transmission Control Protocol

• Verifies that the data delivery process is successful– Internet Protocol.

• Ensures that data packets can be tagged with information needed so as to be sent to specific networks and to specific hosts on those networks

TCP/IP Applications and Technologies—Terms to Know

– Internet Service Provider (ISP):• Uses routers connected to dedicated high-speed

connection to the Internet.• Customers use TCPIP to connect to service

provider.– Hypertext Transfer Protocol (HTTP/HTTPS):

• Used by web browsers to interpret Internet service requests through the URL line

– Secure Sockets Layers (SSL):• Encryption used by HTTPS to secure data

– Transport Layer Security (TLS): • Successor to SSL

TCP/IP Applications and Technologies—Terms to Know

Hypertext Markup Language (HTML):– Code for how web pages are written– Uses “tags" to separate data types, formats, and so on

File Transfer Protocol (FTP):– Widely used to transfer files– Can be used

• In a web browser• From a command line• From specially written FTP programs

Telnet:– Unsecure method of remote access

TCP/IP Applications and Technologies—Terms to Know

Secure Shell (SSH):– Encrypted replacement for telnet

Domain Name Server (DNS):– Takes a web domain request and matches it to the

actual IP address needed to fulfill the request– Part of a worldwide server system– Top-level domains follow the dot “.”

• .com, .gov, .org, and so on

– Like a software phone book of the Internet

TCP/IP Applications and Technologies—Terms to Know

Simple Mail Transport Protocol (SMTP)/Email:– Uses a server to receive and notify clients of email:

• Protocols include SMPT, POP, and IMAP– Email might be thought of as a streamlined way of

putting text in a remote machine’s folder “inbox.” Simple Network Management Protocol (SNMP):

– Used to remotely monitor and manage network devices.

Dynamic Host Configuration Protocol (DHCP)– Used to automatically assign IP Addresses to

network nodes.

TCP/IP Technologies (continued)

Remote Desktop– Uses Remote Desktop Protocol (RDP) to allow remote access

to and control of the desktop GUI for purposes of technical maintenance and troubleshooting

SMB– Server Message Block provides access to file and printers to

multiple clients through authentication.

Lightweight Directory Access Protocol (LDAP)– Microsoft uses this to create Directory Services (Active

Directory).

Ports

16-bit long number assigned to map running applications to the data generated by the application.

– Example of a data request to port 80 on a remote web server:

• The remote web server sees the port 80 request.• It knows that port 80 is the port that is being used

by the web server application.• The web server application responds by retrieving

the data file (web page) and returning it to the client.

• The requesting client receives the data and directs it to the port being used by its web browser.

Common Protocols/PortsProtocol Port Used

FTP 21

SSH 22

Telnet 23

SMTP 2

DNS 53

HTTP 80

POP3 110

IMAP 143

HTTPS 443

RDP 3389

Cable and Connector Types

Unshielded twisted-pair (UTP):– 4 pairs of twisted 26-gauge wire

• Twists provide protection from crosstalk.– Most common type (CAT5, CAT5e cables)

• See Table 16-6 for details.– Uses RJ-45 connector

Shielded twisted-pair (STP):– Has metal braid to protect against EMI

Ethernet Network Types

Wired:– 10Base-T– 100Base-TX– 1000Base-T– Fiber-optic based, such as 1000Base FX

Wireless:– 802.11a—5GHz– 802.11b—2.4GHz– 802.11g—2.4GHz– 802.11n—2.4/5GHz – Bluetooth—Used for Personal Area Networks

Unshielded Versus Shielded Twisted-Pair Cable

UTP/STP Cabling CategoriesCategory Network Type(s)

Supported Supported Speeds Cable Type, Notes

3 10BASE-T Ethernet Up to 10 MbpsUTP; obsolete; replace

with Cat5, Cat5e, or

Cat6.

4 Token ring Up to 16 Mbps Shielded twisted pair

(STP); one-wire pair

5 10BASE-T, 100BASE-T Up to 100 Mbps UTP, STP; four-wire

pairs

5e 10BASE-T, 100BASE-T, 1000BASE-T

Up to 1000 Mbps

Enhanced version of

Cat5; available in UTP,

STP; four-wire pairs

6 10BASE-T, 100BASE-T, 1000BASE-T

Up to 1000 Mbps

Handles higher

frequencies than

Cat5/5e

Ethernet Network Types

Infrared:– Used for short range—laptop to laptop

Cellular:– Digital phone networks

Voice over IP (VOIP):– Digital phone service– Uses Internet provider– Requires specialized knowledge to set up

Bluetooth:– Wireless signal for Personal Area Networks (PAN)

Cable and Connector Types Fiberoptic:

– Single Mode—For long distances; single frequency– Multi-Mode—Shorter distances; multiple frequencies– Subscriber Connector (SC)—Square tip.– Straight Tip (ST)—Round tip– Fiber Connector (FC)—Round connector

Coaxial:– Was used in bus topology; now used by cable TV– RG59 and RG5 with BNC connectors– May require a transceiver to connect to a switch or

host

Insulation and Fire Standards

Wire insulation:– Polyvinyl Chloride (PVC):

• Durable but poisonous when burned– Plenum cable:

• Produces less toxic smoke when burned• Usually required in suspended ceilings

Networking Tools

Wire Scissors Wire Stripper Crimper Punchdown tool LAN Wire Tester Continuity Tester Tone Generator/Probe

Troubleshooting

– Check cable connectors for damage.– Check cable for damage to insulation.– Check link lights on back of PC or switch.– Verify that the correct impedance cable is being

used.

What Have You Learned?

– What type of cable should be purchased when several light frequencies are intended to be used?

– What is the practical limit of CAT5 cable?– Why is the wire twisted in a CAT5 cable?– What advantage does SSH offer over Telnet?– How can HTTPS be useful when doing monetary

transactions?

Chapter 16 (Part A) Summary

Network Models.

– The client/server and peer-to-peer networking models. Internet Connectivity Technologies.

– ISDN, DSL, cable, and satellite. LAN connectivity to the Internet. Network Protocols.

– Basics about TCP/IP. TCP/IP Applications and Technologies.

– The protocols and services that run within TCP/IP. Network Topologies.

– Four topologies you should know for the exam. Network Types.

– Wired and wireless network technologies.

Next Lesson: Chapter 16b