Chapter 21

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

Local Area NetworkingChapter 21


Overview

• In this chapter, you will learn to– Explain network technologies

– Explain network operating systems

– Install and configure wired networks

– Install and configure wireless networks

– Troubleshoot networks


Networking Technologies


The Big Questions

• How will each computer be identified?– If two or more computers want to talk at the same

time, how do you ensure all conversations are understood?

• What kind of wire should be used?– How many wires in the cable? How thick? How

long? What type of connectors?

• How can access to data be controlled?

• And the list goes on and on…


A Few Basics

• A client machine requests information or services

• Network interface card (NIC) defines the client– Breaks data into smaller data units (packets)

• A medium to connect the devices is needed– Wired or wireless

• Operating system needs to be network aware

• A server provides information or services to the client


Topology

• Bus topology– All computers connect to the network via a

main line called a bus cable

• Ring topology– All computers attach

to a central ring of cable


Topology

• Star topology– Computers on the network

connect to a central wiring point (often a switch or a hub)

• Mesh topology– Each computer has a

dedicated line to everyother computer


CompTIA A+Essentials

Essentials

Getting the Right Sound Card

Packets/Frames and NICs


Packets, Frames, and NICs

• Data is broken up into small pieces and moved about the network – Data moved in chunks called packets or frames

• Every network interface card (NIC) has a built-in identifier called a Media Access Control (MAC) address– Designed to be unique– Uses 48-bit long address– Burned into a chip

on the card


Packet Fields

• Packets contain the following fields

– MAC address of destination NIC

– MAC address of source NIC

– Data

– Data check or cyclic redundancy check (CRC) used to verify the data’s integrity


Protocols

• Protocols are sets of rules– May be used to define packet types, cabling and

connectors, addresses, and much more

• A hardware protocol defines how to get data from one computer to another– Ethernet is the dominant standard for today’s

networks• Cables include coaxial, unshielded twisted pair, fiber optic

– Token Ring was developed by IBM but is losing popularity


Coaxial Ethernet

• Early Ethernet networks used coaxial cable (or just coax)

– Composed of a center cable surrounded by insulation, a shield of braided cable, and an outside protective cover

– A different type of coaxial cable is used by your VCRand TV


Thick Ethernet—10Base5

• Thick Ethernet cable used – RG-8 (Radio Grade) cable

– 10Base5• 10 means data is transferred at 10 Mbps• 5 means the maximum length of the cable is 500 meters

– Uses a bus topology

– Computers are connectedone to another

• Every computer receives every packet of information


CSMA/CD

• Carrier sense multiple access/collision detection (CSMA/CD)

• To prevent collisions when there is multiple access to a cable– Computers first do a carrier sense (listen to the

cable for traffic) before trying to send data


CSMA/CD

• If two computers talk (try to send data) at the same time

– A collision results that corrupts the data

– Computers then decide when to resend the data


Reflection and Termination

• Signals traveling along a wire will bounce back when they get to the end – This is called reflection– Can corrupt signal

• A terminator absorbs the reflection

When an electrical signal reaches the end of a wire…

Some of the signalis reflected back

When an electrical signal reaches the end of a terminated wire…

There is no reflection


Connections

• Thicknet marked every 2.5 meters

– Devices are connected at these points

– Vampire connector pierces the cable • It is also a transceiver that transmits and receives data,

sometimes called an access unit interface (AUI) that connects to a Digital, Intel, or Xerox (DIX) connector

• Thicknet uses a bus topology– Break in the cable takes down the whole network


Thicknet Connections


Thin Ethernet—10Base2

• Thin Ethernet is also known as Thinnet

– Uses RG-58 coax – Limited to 30 devices per segment– Cable length limited to 185 meters– Thinner and cheaper than Thicknet– Transceiver built into NIC– Uses twist-on BNC connectors– Uses terminators


UTP Ethernet

• 10/100/1000BaseT (10xBaseT)

– Modern networks use UTP Ethernet

– 10BaseT runs at 10 Mbps

– 100BaseT runs at 100 Mbps

– 1000BaseT (Gigabit) runs at 1000 Mbps

– Uses a star bus topology

– Uses unshielded twisted pair (UTP) cabling


Star Bus Topology

• Most common topology used is a star bus

– All devices are connected to a central device • Can be a hub or a switch

– Switch makes each port a separate network• Limits collisions• Helps bandwidth


Unshielded Twisted Pair

• UTP is predominant type of cabling used– Pairs of wires are twisted together in an

unshielded cable– UTP cables come in categories (CATs) that define

the maximum speed data can be transferred • Called bandwidth• CAT5, CAT5e, and CAT6 are most common today

CAT 1 Standard phone line CAT 2 ISDN & T1 linesSpeeds up to 4 Mbps

CAT 3 Speeds up to 16 Mbps CAT 4 Speeds up to 20 MbpsCAT 5 Speeds up to 100 Mbps CAT 5e Speeds up to 1 GbpsCAT 6 Speeds up to 10 Gbps


Implementing 10xBaseT

• Requires at least two pairs of wires– One for receiving and one for sending

• Cables use RJ-45 connectors– RJ-11 for telephones

• The Telecommunications Industry Association/ Electronics Industries Alliance (TIA/EIA) has two standards for connecting RJ-45 connectors– TIA/EIA 568A and TIA/EIA 568B– Use either but be consistent– Wires are color-coded

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• Ethernet networks share same language

• Many NICs run at 10 or 100 Mbps

• Some NICs have BNCand RJ-45 ports

• Most NICs built into motherboards are autosensing – Run at speed of network

Combo Cards


Hubs and Switches

• Each PC is connected to a hub or switch in a 10xBaseT network

– To add a device, simply run another cable to the hub or switch from the device

– The maximum separation between the device and the hub or switch is 100 meters

– Maximum of 1024 PCs per hub or switch

– Hubs act as repeaters that regenerate the signal before they send it back out to other ports

– Hubs come in 4, 8, 16, or 24 ports


Duplex and Half-Duplex

• Modern NICs can both send and receive data at the same time – Called full duplex

• Older NICs could send and receive data but not at the same time – Called half duplex– Similar to a walkie-talkie


Fiber Optic Ethernet

• Uses light instead of electricity– Immune to electrical interference– Signals can travel up to 2000 meters– Most Ethernet uses 62.5/125 multimode cable– Uses two cables– Uses SC (square-shaped) or ST (round) connectors– Common standards

• 10BaseFL and 100BaseFL

– Usually reserved for data centers due to expense


Token Ring

• Developed by IBM

• Uses a star ring topology– Incompatible with Ethernet– Data travels in a ring

• Uses token passing– A free token circulates the ring– A device may send data only when

it has the token


Implementing Token Ring

• Legacy Token Ring ran at 4 Mbps or 16 Mbps using IBM Type 1 cable

– Two-pair, shielded twisted pair (STP) cable

– Today’s Token Ring networks may use UTP or STP

– STP comes in various types


Token Ring Connectors

• Token Ring cables use an IBM-type Data Connector (IDC)

– Universal Data Connectors (UDC) designed to plug into each other

– Uses a special hub called a multistation access unit (MSAU or MAU)


Other Connections

• Can connect two PCs together

– Parallel/serial • Using crossover IEEE 1284 cable for parallel ports• Use an RS-232 cable for serial ports

– FireWire• Network aware• Just connect

– USB• Not quite as easy as FireWire but possible


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CompTIA A+Technician

Network Operating System


Client/Server

• In a client/server environment, one machine is dedicated as a resource

– Shared over the network

– Uses a special network operating system (NOS)• Optimized for sharing files and printers or other resources• Protects access to the data or resources using security

– Called the server

– All other machines are clients or workstations

– Novell NetWare is an enterprise-level NOS


Peer-to-Peer

• In a peer-to-peer network, any machine on the network can act as client or server

• Peer-to-peer network operating systems include– Windows 2000/XP– Limited to 10 users accessing a file at one time– Microsoft recommends no more than 15 PCs– Useful for small networks only– Limited security– Also referred to as a workgroup


Peer-to-Peer

• User must log on to each individual computer– Multiple computers, multiple logons


Domain-Based

• User logs onto domain controller– One user, one logon– Can access all computers (unless locked down

with security)


Domain-Based

• Servers on the network may play one or several roles– Domain controller (holds the security database)– File server– Print server– Fax server– Remote access services

(RAS) server– Application server– Web server


Administrator Account

• Special user account that has complete and absolute power over entire system

• Password should be protected

• Joining a workgroup or becoming part of a domain is relatively easy– Need Administrator access


Joining a Workgroup or Domain in Windows 98

• Joining a workgroup or becoming part of a domain is relatively easy– Need Administrator access– Select computer properties


Protocols

• Network protocol software– Takes incoming data received by the network card– Keeps it organized– Sends it to the application that needs it– Takes outgoing data from application and hands it

over to the NIC to be sent out over the network

• The most common protocols used are– NetBEUI—nonroutable, rarely used today– IPX/SPX—used by Novell– TCP/IP—used on Internet and most networks– AppleTalk—proprietary Apple protocol


Client and Server Software

• Client software– Needed to access data and resources on a network– Windows installs Client for Microsoft Networks

• Server software– Any Windows PC may be turned

into a server by enabling sharing of files, folders, and printers


Installing and Configuring a Wired Network

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Network Connectivity

• To connect to a network you need

– Network interface card• Physical hardware that connects the PC to the network wire

– Protocol• The language the devices use to communicate

– Network client• Allows the computer system to speak to the protocol

– To share resources, enable Microsoft’s File and Print Sharing


Installing a NIC

• When choosing a NIC, there are three requirements– Must run at the proper speed (many NICs run at

more than one speed)– Must be for the proper technology

• Ethernet, Token Ring, fiber optic (FDDI)

– Must fit into your expansion slot• PCI

• If NIC does not autoinstall, then use the Add Hardware Wizard in Control Panel


Configuring a Network Client

• You need a network client for each type of server NOS

– Client for Microsoft Networks• Right-click My Network Places (or Network Neighborhood)

and choose Properties• Double-click the Local Area Connection icon (or choose

Create a New Network Connection) and select Properties• Client for Microsoft Networks is automatically installed

when you install a NIC in Windows

– Client Service for NetWare• Provides access to file and print services on NetWare

servers


Client for Microsoft Networks


NetBEUI in Windows 2000

• NetBEUI– Windows 2000: Start Settings Network and

Dial-up Connections Double-click the Local Area Connection icon

– Click the Properties button

– Click Install button, highlight Protocols, and click Add NetBEUI

– Windows XP has dropped support for NetBEUI


NetBEUI

• NetBEUI– Not routable (can’t go through routers)– Rarely used today


NWLink

• Microsoft’s implementation of IPX/SPX

– You’ll also need to install Client Services for NetWare

– Install the same way you install NetBEUI but choose NWLink instead


Configuring TCP/IP

• TCP/IP is the most widely used protocol suite in networks today

– It is the protocol of choice for the Internet but is also used on private networks

– TCP/IP is installed just like NetBEUI and NWLink—simply choose Internet Protocol (TCP/IP)

– You’ll need to configure an IP address and a subnet mask at the very least


IP Addressing

• IP addresses are unique on a network

• Expressed in dotted-decimal notation– 202.34.16.11

• Composed of 32 bits in four octets– 202 expressed as 1 1 0 0 1 0 1 0 – 34 expressed as 0 0 1 0 0 0 1 0– 16 expressed as 0 0 0 0 1 0 0 0– 11 expressed as 0 0 0 0 1 0 1 1


IP Addressing

• IP addresses are broken into classes based on the size of the network– First number in dotted-decimal format

determines class• 15.16.17.18 15 is Class A• 192.7.8.9 192 is Class C

– First number also determines subnet mask

Class Address Range Subnet MaskClass A 1–126 255.0.0.0Class B 128–191 255.255.0.0

Class C 192–223 255.255.255.0


Classes of IP Addresses

• Some addresses are reserved

– 127.0.0.1 (the loopback address) is reserved for testing

– Three ranges are reserved for private networks• 10.0.0.1 thru 10.255.255.255.254• 172.16.0.1 thru 172.31.255.254• 192.168.0.0 thru 192.168.255.254

– One range is reserved for Automatic Private IP Addressing

• 169.254.0.1 thru 169.254.255.254


Subnet Mask

• The subnet mask defines which portion of the IP address belongs to the network ID and which part belongs to the host ID

– Expressed as dotted-decimal format as 32-bit number starting with 1s and ending with 0s

– 1s represent a network-ID bit and 0s represent a host-ID bit

• For example, 11111111.00000000.00000000.0000000 means that the first 8 bits define the network ID and the last 24 bits define the host ID

– The subnet mask is associated with an IP address


IP Addresses

• Two parts of an IP address– Network ID represents the network or subnet – Host ID represents the individual device

• You determine which is which with the subnet mask– When the subnet mask is maximum, that portion of

the IP address is the network ID

192.168.1.15 10.15.16.17 IP address255.255.255.0 255.0.0.0 Subnet Mask192.168.1.0 10.0.0.0 Network ID


TCP/IP Services

• TCP/IP is an entire suite of protocols that offers TCP/IP services such as– Hypertext Transfer Protocol (HTTP) used on the

World Wide Web– Telnet used to access remote systems– Ping to check communication

• TCP/IP is used to link multiple networks (local area networks or LANs) with other networks – Forms a wide area network (WAN)– Routers are used to route traffic among the LANs


Typical LAN

• Shows two networks or subnets– Router is path to other network

• This router has two NICs (one on each network)• Data sent from CPU1 to CPU2 goes through Default

Gateway (different subnet)

Router

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Subnet 2 Network ID 192.168.15.0255.255.255.0

Subnet 1 Network ID 192.168.1.0255.255.255.0

Default gateway

Default gateway

CPU1 CPU2


TCP/IP Settings

• Domain name service (DNS)

– To reach any host on a TCP/IP network, you need to know the IP address

– Instead of remembering IP addresses, you most likely simply remember a user-friendly name

– DNS resolves user-friendly names to actual IP addresses (name resolution)


Name Resolution

• Two types of names– Internet (host) and Windows (NetBIOS)

• Seven types of name resolution– Focus here only on DNS and WINS

Name Type Static Dynamic CacheHostInternet name

HOSTS file

DNSserver

Hosts cache View with IPConfig /DisplayDNS

NetBIOS

Windows name

LMHosts file

WINSserver

NetBIOS cache View with NBTSTAT –C

Broadcast


TCP/IP Settings

• Windows Internet Name Service (WINS)

– Enables Windows network names to be resolved to IP addresses (like DNS does for Internet names)

– When configuring a NIC, you would define the IP address of the WINS server

– WINS is being used less and less


TCP/IP Settings

• IP address

• Subnet mask

• Default gateway– The address of a

machine (usually a router) that will deliver messages to hosts outside of your local segment or subnet


TCP/IP Settings: DHCP

• Dynamic host configuration protocol– Can manually configure

TCP/IP settings

– Can configure to get TCP/IP settings automatically(from DHCP)

– Requires DHCP server

– On the client computer, simply choose Obtain an IP address Automatically


TCP/IP Tools: Ping

• Ping– Tests connectivity to a remote host– Many options use ping /? for help


TCP/IP Tools: IPCONFIG

• IPCONFIG– Displays your TCP/IP settings in Windows

NT/2000/XP– Release and Renew allows you to get new TCP/IP

information from a DHCP server


TCP/IP Tools: NSLOOKUP

• NSLOOKUP– Determines the name of a DNS server among

other things• Type exit to return to the command prompt


TCP/IP Tools: TRACERT

• TRACERT– Shows the route a packet takes to its destination


TCP/IP Tools: APIPA

• Automatic Private IP Addressing (APIPA)– If set to get addresses from DHCP but DHCP server

cannot be reached, APIPA address is assigned• Automatically assigns an IP address in range 169.254.0.0

thru 169.254.255.254 with a subnet mask of 255.255.0.0• No routing capabilities

Router

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CPU1

DHCP

DHCP can’t be reachedAPIPA address assigned


Sharing Drives and Folders

• To share a drive or folder, right-click it and select Sharing

– Share name is the name others will see on the network

– Windows 2000/XP uses NTFS-formatted drives

• Allows for much greater and precise control• Set the network (Sharing tab) permissions to Full Control• Then use NTFS permissions (Security tab) to exercise more

precise control over who accesses the shared resource and how they access them


Sharing Drives and Folders

• Share Permissions– Full Control– Change– Read– NTFS Permissions

allow more control


Accessing Shared Resources

• Access shared drives or folders using My Network Places (Windows 2000/XP)– You may also map a drive letter to a shared drive

or folder– Windows 2000 allows you to add a network icon

instead of using a drive letter– Windows XP adds a menu option


UNC

• Universal Naming Convention (UNC) – Allows you to access network resources as follows

– Can enter directly from Run line to access UNC path

\\SERVER1\FREDC

Computer name

Share name


Sharing Printers

• To share a printer, just right-click on the printer and choose Sharing

• To access the printer

– Use the Add Printer icon

– Select Network Printer instead of Local Printer


CompTIA A+Essentials

Essentials

Getting the Right Sound CardInstalling and Configuring

a Wireless Network


Introduction

• Wireless networks are growing in popularity

• Wireless networks use radio waves or beams of infrared light to communicate with each other

• Two primary types of wireless networks– Based on IEEE 802.11 standard – Based on Bluetooth technology


Wireless Networking Components

• Many capabilities built-in today

– Infrared ports standard in laptops, PDAs, and high-end printers

– Infrared not usually included in desktop PCs



• Wireless Ethernet and Bluetooth often integrated or can easily be added– USB, PCI, PCI Express, or PC Card adapters



• Wireless access point (WAP)– Acts like a hub to the wireless hosts in the area

• Bluetooth– Built-in option on many

newer PCs


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CompTIA A+Technician

Wireless Networking Software


Wireless Networking Software

• Wireless devices use same networking clients and protocol as wired networks

– Use CSMA/CA (CA stands for collision avoidance)

• Another option is using Request to Send/Clear to Send (RTS/CTS)

• Sending node issues an RTS to the receiving node as a request

• Receiving node replies with a CTS when it’s clear

• Once data is received, receiving node sends an ACK (acknowledge)


Wireless Configuration Utility

• Wireless networking software is PnP– Use a utility to configure parameters

• Windows built-in utility or vendor provided• Configure the Service Set Identifier (SSID) here


Wireless Networking Modes

• Ad-hoc mode

– Each wireless node is in direct contact with every other node in a decentralized free-for-all

– Form an Independent BasicService Set (IBSS)

– Called peer-to-peer mode

– Good for a few computers or temporary network such as study groups or business meetings


Wireless Networking Modes

• Infrastructure Mode

– Use one or more WAPs to connect wireless nodes to a wired network segment

– A single WAP is called a Basic Service Set (BSS)

– Additional WAPs create an Extended Basic Service Set (EBSS)


Wireless Networking Security

• Three methods used to enhance security

1. Service Set Identifier (SSID)– Configure a unique SSID or network name

• Default is often name of vendor such as “LinkSys”• Widely known so easy to guess

– Each node needs to have the same SSID– Turn off SSID broadcasting

2. MAC filtering– Filtering based on each host’s MAC address– Creates a type of accepted user– Included in each packet, so can be discovered

and impersonated


Wireless Networking Security

• Wireless Equivalency Privacy (WEP)– Encrypts data using 40-bit or 104-bit encryption– Provides authentication based on MAC addresses– Significant flaws

• Wi-Fi Protected Access (WPA)– Interim upgrade to WEP– Uses encryption key integrity-checking

• WPA2 (IEEE 802.11i )– Full upgrade to WEP – Significant improvements– Current wireless security standard


Speed and Range Issues

• Wireless speeds range from 2 Mbps to54 Mbps

• Speed affected by range– Speed dynamically negotiated– Maximum throughput at approximately 25 feet– At edge of range, throughput may decrease to

1 Mbps– Range not exact

• Often listed as around 150 feet or 300 feet


Wireless Networking Standards

• 802.11-based wireless networking– Three primary standards– All can work in ad-hoc or infrastructure modes

802.11a 802.11b 802.11gMaxthroughput

54 Mbps 11 Mbps 54 Mbps

Max range 150 feet 300 feet 300 feetFrequency 5 GHz 2.4 Ghz 2.4 GhzSecurity SSID, MAC,

WEP, WPASSID, MAC, WEP, WPA

SSID, MAC, WEP, WPA

Compatibility 802.11a 802.11b 802.11b, 802.11g



• Infrared wireless networking– Simple way to share data without adding any additional

hardware or software– Uses the Infrared Data Association (IrDA) protocol– Line-of-sight required– No authentication or encryption

• You can’t be more than 1 meter away

Infrared (IrDA)Max throughput Up to 4 MbpsMax range 1 meter (39 inches)Security NoneCompatibility IrDACommunication mode Point-to-point ad-hoc



• Bluetooth

– Designed to create small wireless personal area networks (PANs)

– Typically used for peripherals• Mice, keyboards, PDAs, etc.

Bluetooth High-powered BluetoothMax throughput 1 Mbps 2 MbpsMax range 10 meters 300 feetCompatibility Bluetooth BluetoothCommunication mode

PAN PAN



• Cellular

– Many PDAs and phones today allow connection to Internet

– Downloads as quick as 400 to 700 Kbps

– Cellular networks have their own protocols

– Downside is the price


Configuring Wireless Networks

• Physically installing a wireless NIC is the same as installing a wired NIC

• Wireless network configuration utility– Used to configure additional

parameters

– Configure SSID and encryption

– Configure communication mode• Ad-hoc• Infrastructure



• Wi-Fi– Ad hoc

• Each wireless node needs to be configured with the same network name (SSID)

• May need to select a common channel• Configure unique host IP addresses• Configure File and Printer Sharing

– Infrastructure modes• Requires a wireless access point (WAP)• All nodes need to be configured with the same SSID• Configure the WAP with clients that match the chosen

options



NETGEARwireless configurationutility



• Configuring a wireless access point is often done through a Web browser

– Enter the WAP’s default IP address (see your documentation or try 192.168.1.1) in your browser

– Enter the default administrative password (in your documentation) to log in

• The next few slides show some screenshots of the configuration pages



• Sample home page



• Configuring MACaddress filtering



• Configuring encryption



• Infrared– Not much to configure

– Confirm the IrDA protocol is installed

– To transfer files• Use Wireless Link applet• Use Windows Explorer

– To network two computers• Choose Connect Directly to

Another Computer



• Bluetooth– Completely plug and play

• May need to use vendor-supplied drivers

– Bluetooth devices seek each other out

• Establish a master/slave relationship

– PANs sometimes have specialized software utility


Troubleshooting Networks



• Networked and non-networked situations differ drastically– Networked situations add complexity

Routeror switch

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CPU1

Print server

If a user can’t print from CPU1, it could be due to many possible problems on the network.

Networked printer



1. Verify the symptom– Talk with the user to try to get a precise

description of the symptoms

2. When did it happen?– Does it happen during boot, when the OS loads, or

after the system has been running for a while?

3. What has changed?– Try to find out if anything has changed– Even recent changes before the problem

began occurring



4. Check the environment– Heat, humidity, dirt– What OS? What applications? Do others use

the computer?

5. Reproduce the problem– If a problem happens only once, it’s not a problem– Otherwise, try to make the problem happen again

6. Isolate the symptom– Hardware—remove suspect parts – Software—remove background programs or boot

into Safe Mode



7. Separate hardware from software– Replace the suspect hardware with known

good hardware – Uninstall the suspect software and reinstall it– Install the latest patch or upgrade– Check for viruses

8. Research– Use search engines on the Internet

9. Make the fix and test– Keep track of what you did so you may return to

the previous state if the fix does not work


OSI Seven-Layer Model

• Use as a guide in troubleshooting

Layer Number Name DescriptionLayer 1: Please Physical NICs (link light), cables,

switches, hubs, etc. 1s, 0sLayer 2: Do Data Link MAC addresses and

CSMA/CDLayer 3: Not Network IP operates hereLayer 4: Throw the

Transport TCP/UDP operate here

Layer 5: Sausage Session Manages connections

Layer 6: Pizza Presentation Describes how to present data

Layer 7: Away Application Interacts with user


Mike’s Four-Layer Model

• Hardware– Check the hardware starting with the physical layer

• Protocols– Is it installed and configured properly?

• Network– Servers and nonservers– Check users and groups and share names

• Shared resources– Make sure the resource has been properly shared– Check the access allowed

Chapter 21

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Transcript of Chapter 21