Computer Network

& Security
ITCNA1-12
Computer Network
& Security
ITCNA1-12
 Lesson 3

Troubleshooting PC Hardware
Objectives
• Apply troubleshooting methodology

• Configure BIOS/UEFI

• Troubleshoot power and disk issues

• Troubleshoot system and display issues

3
 Lesson 3

Topic 3A
Apply Troubleshooting Methodology

4
Best Practice Methodology
• Problem solving • CompTIA troubleshooting
model
• Causes, symptoms,
consequences 1. Identify the problem
• Context 2. Establish a theory

• Corporate policies, procedures, 3. Test the theory

impacts
4. Establish an action plan
5. Verify full system functionality
6. Document findings

5
Identify the Problem
• Gather information from users
• Identify user changes
• Inquire regarding environmental or infrastructure changes

• Perform backups before making changes

6
Establish and Test a Theory

• Establish a theory
• From possible causes to probable cause

• Conduct internal or external research

• Physical inspection
• Internal documentation and support resources
• External vendor and forum resources

7
Establish and Test a Theory

• Question the obvious

• Attention to detail
• Step through what should happen
• Compartmentalize the issue
Establish a New Theory or Escalate
• Establish a new theory
• Question the obvious (again)
• Consider alternatives/workarounds
• Take system “back to base”

• Escalate
• Escalation paths
• Communicate support case status
Implement a Plan of Action

• Next steps
• Repair, replace, workaround
• Risks from costs and impacts

• Example: If a laptop battery fails, a repair might involve replacing

only the cells, while a full replacement would mean buying a new
battery. If both options are expensive, a workaround could be using
the laptop plugged into power.
Implement a Plan of Action

• Establish a plan of action

• Consider impacts
• Consider corporate policies, procedures, and impacts before
implementing changes
• Implement the solution
• Change management and scheduling
• Refer to vendor instructions
Verify and Document

• Verify full system functionality

• Perform tests
• Obtain user acceptance
Verify and Document

• Implement preventive measures

• Document findings, actions, and outcomes
• Ticketing systems
 Review Activity: Troubleshooting Methodology
• Best Practice Methodology
• Identify the Problem
• Establish and Test a Theory
• Establish a New Theory or Escalate
• Implement a Plan of Action
• Verify and Document
Lesson 3

Topic 3B
Configure BIOS/UEFI

15
BIOS and UEFI
• System firmware
• Basic Input/Output System
(BIOS)
• Unified Extensible Firmware
Interface (UEFI)
• Accessing system setup

16
Boot and Device Options

• Boot device selection and

priority
Boot and Device Options

• USB permissions
• Fan considerations
Boot Passwords and Secure Boot
• System password
• User password
• Secure boot
Trusted Platform Modules
• Encryption and cryptographic
keys
• Hashes
• Trusted platform module (TPM)
• Root of trust
• Secure key storage

• Hardware security module

(HSM)
20
 Review Activity: BIOS/UEFI
• BIOS and UEFI
• Boot and Device Options
• Boot Passwords and Secure Boot
• Trusted Platform Modules
 Lesson 3

Topic 3C
Troubleshoot Power and Disk Issues

22
Troubleshoot Power Issues
• No power symptoms
• No indicator lights
• Fans do not start
• Possible causes
• Circuit fault or power blackout
• Socket fault
• Switches and cables/connectors
• Overloaded and faulty devices
• Power supply testing Konstantin Malkov @123RF.com
Troubleshoot POST Issues
• Power-on self-test (POST)
• Black screen
• Failed firmware update
• Faulty cabling/connector/device
• Faulty PSU or CPU

• Beep codes
Codes for the original IBM PC are listed in this table
Troubleshoot Boot Issues
• Boot device
• Boot sequence
• Power and data connectors and
cabling

Screenshot courtesy of Microsoft

26
Troubleshoot Boot Issues

• Boot sector
• Damage to boot/partition records

Screenshot courtesy of Microsoft

27
Troubleshoot Boot Issues

• OS errors and crash screens

• Hardware fault or OS/driver fault

Screenshot courtesy of Microsoft

28
Troubleshoot Drive Availability
• Unusual noises
• Light-emitting diode (LED) status indicators
• No LED activity
• Constant LED activity

• Missing drives in OS
• Read/write failure
• Blue Screen of Death (BSoD)
Troubleshoot Drive Reliability and Performance
• Self-monitoring, Analysis, and
Reporting Technology (SMART)
• Report errors

• Vendor and third-party diagnostic

utilities
• Input/output operations per second
(IOPS) measurement
• Benchmark performance without
interference from OS/app causes

• Data loss/corruption
• Bad sectors and bad blocks

• Backup and data recovery

Troubleshoot RAID Failure
• RAID array degraded
• Backup
• Replace failed device

• RAID device not found

• Controller
seating/cables/connectors
• Drivers
• RAID configuration utility
 Review Activity: Power and Disk Issues
• Troubleshoot Power Issues
• Troubleshoot POST Issues
• Troubleshoot Boot Issues
• Troubleshoot Drive Availability
• Troubleshoot Drive Reliability and Performance
• Troubleshoot RAID Failure
 Lesson 3

Topic 3D
Troubleshoot System and Display
Issues

33
Troubleshoot Component Issues

• Intermittent shutdown and application crashes

• Software versus hardware causes
• Overheating and burning smells
• Clean chassis, heatsinks, and fans
• Verify airflow
Troubleshoot Component Issues

• Physical damage
• Bent pins and other connector/cabling damage
• Component/adapter seating (chip creep)
• Capacitor swelling
Troubleshoot Performance Issues
• Check for overheating
• CPU throttling/overheating

• Check for misconfigurations

• What has changed?

• Verify the problem

• Use diagnostic software to quantify performance loss
• Identify best opportunity for upgrade (compute, storage, networking)

• Rule out operating system/app/configuration/networking issues

Troubleshoot Inaccurate System Date/Time
• Problems caused by inaccurate
date/time
• Real time clock (RTC) battery
replacement

Image @123RF.com
Troubleshoot Missing Video Issues
• Incorrect data source
• Adapter outputs and monitor
inputs
• On-screen display (OSD)

• Physical cabling issues

• Damaged connectors
• Cable application/performance

• Burned-out bulb
Image @123RF.com
• Intermittent projector shutdown
Troubleshoot Video Quality Issues (Slide 1 of 2)
• Dim image
• OSD controls
• Power saving modes
• Backlight failure

• Fuzzy image
• Flashing screen
• Faulty connector, display elements/backlight, or video card
Troubleshoot Video Quality Issues (Slide 2 of 2)
• Dead pixels
• Burn-in
• Incorrect color display
• Accurate calibration
• Connector/adapter/cable faults

• Audio issues

Screenshot courtesy of Microsoft

 Review Activity: System and Display Issues
• Troubleshoot Component Issues
• Troubleshoot Performance Issues
• Troubleshoot Inaccurate System Date/Time
• Troubleshoot Missing Video Issues
• Troubleshoot Video Quality Issues
Computer Network
& Security
ITCNA1-12
 Lesson 4
Comparing Local Networking Hardware

Objectives
• Compare network types

• Compare networking hardware

• Explain network cable types

• Compare wireless networking types

43
 Lesson 4

Topic 4A
Compare Network Types

44
LANs and WANs: Network Infrastructure
LANs and WANs
Wide area network (WAN)

• A WAN (Wide Area Network) is a network that connects multiple LANs (Local
Area Networks) over long distances. It allows computers in different cities,
countries, or even worldwide to communicate.

• WANs connect LANs using the internet, leased cables, satellites, or radio signals.
A company or ISP (Internet Service Provider) manages the connection.
• Unlike LAN, WANs cover large areas (cities, countries, or even the world).
Metropolitan area network (MAN)
A network covering a city or municipality (larger than a LAN, smaller than a
WAN).
Example: A city’s government offices sharing a network across different
buildings.
SOHO
• Small Office Home Office
(SOHO)
• The SOHO network allows
computers in a home office or a
remote office to connect to a
corporate network, or access
centralized, shared resources.

• Single appliance provides

Ethernet, Wi-Fi, and Internet
connectivity
Image © 123RF.com
SOHO and Enterprise Networks
• Enterprise networks
• Reliability and scalability
• Modular design

Image © 123RF.com
SOHO
Datacenters and Storage Area Networks
• Datacenter
• Facility dedicated to hosting servers
• Networking, power, climate control, and physical access control features

A Data Center is a large facility designed to store, manage, and process

data. It contains many powerful computers (servers) that provide services
like websites, cloud storage, and online applications.
Datacenters and Storage Area Networks
Storage area network (SAN)
A Storage Area Network (SAN) is a special network just for
storing data. Instead of keeping data on each computer, all data is
stored on a shared system that multiple computers (servers) can
access.
• Network hosting configurable pool of storage devices
• Clients of the network are application servers (not ordinary workstations)
• Clients treat storage as logical disk
• Fiber Channel and Internet SCSI (iSCSI)
Personal Area Networks
A Personal Area Network (PAN) is a small network that connects devices close to
you (within a few meters). It allows your phone, laptop, smartwatch, and other
devices to communicate wirelessly.
• Wireless and cellular connections over a few meters
• PC and smartphone
• PC/smartphone and peripheral devices
• Internet of Things and wearable technology
 Lesson 4

Topic 4B
Compare Networking Hardware

57
Network Interface Cards

A Network Interface Card (NIC) is a hardware component that allows a computer,

laptop, or other device to connect to a network (like the internet or a local
network). It acts like a bridge between your computer and the network.

1. Establishing a Physical.
2. Supporting Different Ethernet Types
3. Increasing Network Speed

Data Framing and Addressing

MAC Address
Network Interface Cards
• Media type (transceiver)
• Electrical versus optical

• Number of ports
• Framing and addressing
• Media access control (MAC)
address
• Source and destination
Screenshot courtesy of Wireshark
• Hex notation
Patch Panels
• Back
• Terminate cabling from wall ports
to insulation displacement Image by plus69 © 123RF.com

connector (IDC) blocks

• Front
• Modular RJ-45 connectors
• Use patch cords to connect to
switch ports

Svetlana Kurochkina © 123RF.com

60
Hubs
• Star topology wiring
• Concentrator repeats signals over
all cabled segments

• Hub
• All ports are in same collision
domain
• Performance reduced by
contention
Image © 123RF.com
• Half-duplex 10/100 Mbps
Ethernet only
Hubs
Feature Hub (Old Technology) Switch (Modern Technology)
Device Type Broadcasts data to all devices Sends data only to the intended device

Communication Type Half-Duplex (Send or receive, not both) Full-Duplex (Send and receive at the same time)

Sends data to all connected devices (causing Sends data only to the intended recipient
Data Transmission
network congestion) (efficient)
Collision Handling Collisions occur frequently No collisions due to intelligent forwarding
Faster because each device has dedicated
Speed Slow due to shared bandwidth
bandwidth
MAC Address Usage Does not use MAC addresses Uses MAC addresses to send data efficiently
Works well in large networks with many
Network Size Works best in small networks with a few devices
devices

Scalability Not scalable for modern networks Scalable for enterprise and high-speed networks

Supports Fast Ethernet, Gigabit, and even 10-

Ethernet Compatibility No support for Gigabit Ethernet
Gigabit Ethernet

62
Switches

A switch is a network device that connects multiple devices and directs data only to the
intended recipient. Unlike a hub, which blindly sends data to all connected devices, a switch
is intelligent. It reads the MAC address (a unique hardware identifier) of each device and
forwards data only to the device it is meant for.

How Does a Switch Work?

1.A computer sends data across the network.

2.The switch receives the data and checks the destination MAC address.
3.It looks up its internal table to see which port is connected to that MAC address.
4.The switch forwards the data only to that specific device, rather than sending it to all
connected devices.
Switches
• Same star topology—each host
cabled to a switch port
• Switch forwards traffic to
specific destination port by
learning MAC addresses
• Allows each port to operate at
full-duplex and full speed
• Required for Gigabit Ethernet
Image © 123RF.com and better
Unmanaged and Managed Switches

Unmanaged switch

Unmanaged Switches enable Ethernet devices such as computers and printers to

communicate with each other.
Unlike Managed Switches, Unmanaged Switches come with a fixed configuration
that is not editable.
Primarily Unmanaged Switches are used in small networks where network traffic
is light and flows unrestricted between devices without the need for giving
priority to packets.
Unmanaged and Managed Switches

Managed switch
A managed switch allows network administrators to configure settings,
monitor performance, and control traffic.
These are used in larger businesses where security, performance, and reliability
are critical.

Images at © 123RF.com
Unmanaged and Managed Switches

Managed Switches
I. Configuration Options: Administrators can control traffic, security, and performance.
II. Remote Management: Can be accessed via a dedicated management port or over
the network.
III. More Ports: Commonly have 24 or 48 ports to connect multiple devices.

I. Security Features: Can implement firewalls, VLANs (Virtual LANs), and traffic
monitoring to protect data.
II. Rack-Mounted: Designed to fit in network racks used in data centres or enterprise
networks.

Images at © 123RF.com
Power over Ethernet

Power over Ethernet (PoE) is a technology that allows both power and data to be
transmitted over a single Ethernet cable. This eliminates the need for separate power cables,
making it efficient and cost-effective for networking devices such as:

VoIP phones (used for internet-based calls).

Security cameras (CCTV and IP cameras).
Wireless access points (APs) (used for Wi-Fi coverage).
Power over Ethernet

• PoE standards
• 802.3af (~ 13 W)
• 802.3at (PoE+) (~ 25 W)
• 802.3bt (Ultra PoE) (~ 51 W (Type 3) or 73 W (Type 4)
Power over Ethernet
There are two ways to supply PoE:

1.PoE Switch (Endspan PSE)

1. A switch with built-in PoE support supplies power directly through the Ethernet
cable.
2. Example: A corporate office installs a PoE switch to power Wi-Fi access points,
so they don’t need separate power adapters.
2.Power Injector (Midspan PSE)
1. If a switch does not support PoE, a PoE power injector (or midspan injector) is
used.
2. The injector is placed between the switch and the device, adding power to the
Ethernet cable.
3. Example: A small business has a non-PoE switch but wants to install a security
camera that requires PoE. Instead of replacing the switch, they use a power
injector.
 Lesson 4

Topic 4C
Explain Network Cable Types

73
Unshielded Twisted Pair (UTP)
• Copper wire cabling carrying
electrical signals
• Four balanced wire pairs
• Twisted at different rates and
balanced to reduce
interference
• Signal attenuation limits
maximum distance to 100 m
Image © 123RF.com
Shielded Twisted Pair
• Screening or shielding as extra protection
against interference
• Used for 10G Ethernet+ in datacenters for
higher reliability

• Used when cabling is near external interference

sources (fluorescent lighting, power lines,
motors, and generators)

• Screened cable has one thin outer foil shield

around all pairs (ScTP, F/UTP, FTP)
• Fully shielded cabling has a braided outer
screen and foil-shielded pairs (S/FTP and
Public domain image by Baran Ivo F/FTP)
• Shield elements in cable, connector, and
patch panels must be bonded
Cat Standards

23
Copper Cabling Connectors

Images © 123RF.com

24
Copper Cabling Installation Tools

• Patch cords are crimped to RJ-45

connectors
• Structured cable is terminated to
insulation displacement connect (IDC)
blocks in wall ports and patch panels

25
Copper Cabling Installation Tools

• Cable stripper
• Remove insulation

25
Copper Cabling Installation Tools

• Punchdown tool
• Terminate to IDCs

25
Copper Cabling Installation Tools

• Crimper
• Add RJ-45 connector

25
Copper Cabling Test Tools

• Validate and test cable

installation
• Cable tester
• Verify termination
Copper Cabling Test Tools

• Cable tester
• Verify termination

• Toner probe
• Trace a cable

• Loopback plug
Image by samum © 123RF.com Images © 123RF.com
• Test NIC or switch port
Copper Cabling Test Tools

• Trace a cable

• Loopback plug
• Test NIC or switch port

Image by samum © 123RF.com Images © 123RF.com

Copper Cabling Test Tools
• Validate and test cable
installation
• Cable tester
• Verify termination

• Toner probe
• Trace a cable

• Loopback plug
• Test NIC or switch port
Network Taps
• Capture network traffic
• Passive test access point (TAP)
• Active TAP
• Mirror port
Copper Cabling Installation Considerations
• Installation to plenum spaces
• Building/fire safety regulations
• Plenum rated cable

• Installation as outside plant (OSP)

• Aerial, conduit, and direct burial
• Protection against weathering
Copper Cabling Installation Considerations
Optical Cabling
• Fiber optic cable types
Image by atrush © 123RF.com • Single-mode fiber (SMF)
• Multi-mode fiber (MMF)

• Connector types
• Straight tip (ST)
• Subscriber connector (SC)
Image by YANAWUT SUNTORNKIJ ©
123RF.com • Lucent connector (LC)
Coaxial Cabling
• Coaxial cable
• Construction

Image by destinacigdem © 123RF.com • Uses

• F-type connector

Image © 123RF.com 30
 Lesson 4

Topic 4D
Compare Wireless Networking Types

92
Access Points
• IEEE 802.11 / Wi-Fi
• Infrastructure mode WLAN
• Access point interconnects wireless
clients (stations)
• Infrastructure Basic Service Set
(BSS)
• Basic Service Set Identifier (BSSID)
• MAC address of AP radio
• Can bridge with wired network via
a switch
Image © 123RF.com
802.11a and the 5 GHz Frequency Band
• 2.4 GHz
• Better propagation, but fewer
channels and greater interference
risk
• 5 GHz
• Shorter range, but less congested
• IEEE 802.11a (54 Mbps)
• 23 x non-overlapping 20 MHz
channels
• Dynamic Frequency Selection (DFS)
and regulatory impacts
802.11b/g and the 2.4 GHz Frequency Band
• IEEE 802.11b (11 Mbps)
• 14 x 5 MHz channels
• Wi-Fi still needs 20 MHz channel
bandwidth
• Channels require careful
configuration to avoid overlap

• IEEE 802.11g (54 Mbps)

• 802.11b compatibility mode
802.11n
• Dual band radios
• 5 GHz or 2.4 GHz

• 40 MHz channel bonding

• Multiple input multiple output
(MIMO)
• Use of multiple antennas to improve
reliability and bandwidth
• 72 Mbps per stream

• Wi-Fi 4
Wi-Fi 5 and Wi-Fi 6
• Wi-Fi 5 (802.11ac)
• 5 GHz only

• Tri-band radios

• 80 and 160 MHz channel bonding

• Multiuser MIMO
• Connect stations simultaneously

• Wi-Fi 6 (802.11ax)
• 2.4 GHz or 5 GHz (plus new 6 GHz band)

• Downlink and uplink MU-MIMO

• Orthogonal frequency division multiple access

(OFDMA)
Wireless LAN Installation Considerations
• Network name or Service Set
Identifier (SSID)
• Frequency band use
• Same SSID or different SSID per
band
• Operation mode (legacy standards
support)
• Channel usage
• Non-overlapping
• Channel width/bonding
Screenshot courtesy of TP-Link
Wi-Fi Analyzers
• Software installed to mobile device
• Reports configuration of nearby wireless
networks

• Signal strength on each channel

• Signal strength
• Decibels-milliwatt (dBm)

• Negative values with closer to zero better

performance

• Logarithmic scale

• 3 dBm difference represents halving or

doubling
MetaGeek, LLC. © Copyright 2005-2021
• Signal-to-noise ratio (SNR)
Long Range Fixed Wireless
• Wireless bridges configured using microwave antennas
• Line of sight
• High gain
• Licensed spectrum use
• Legal right to remove interference sources
• Unlicensed spectrum
• Shared use of frequency band
• Regulatory requirements on power
• Transmit power, gain, and Effective Isotropic Radiated Power (EIRP)
Bluetooth, RFID, and NFC
• Bluetooth
• Connectivity for wireless
peripherals

• Radio Frequency ID (RFI)

• Wireless asset tags
• Inventory control

• Nearfield Communications
Image © 123RF.com
(NFC)
• Contactless payments
Bluetooth, RFID, and NFC
• What are the indicators
that show this is email
spoofing
• List what you see
• Discuss in pairs the steps
you need to take when you
receive an email like this
• Share in class what you
would do
• Each pair share 1 point and
explain