C393 - IT Foundations (A+ Core 1)
Exam Compass -> Professor Messer -> Dion Practice -> Win.
Last updated: May 4th, 2023
Course Notes
Module 1: Mobile Devices
Laptop Displays
- Portable LCD
- Advantages
- Lightweight
- Low power consumption
- Relatively Inexpensive
- Disadvantages
- Black level challenges
- Requires backlight
- Lights are difficult to replace
- Backlight Tech
- CCFL
- Cold Cathode Fluorescent Lamp
- Uses mercury
- Not as efficient as LEDs
- TN
- Twisted Nematic
- Fast response time
- Low viewing angle
- IPS
- In-Plane Switching
- Excellent Color
- More Expensive than TN
- VA
- Vertical Alignment
- Compromise between TN and IPS
- Slow response time
- OLED
- Organic Light Emitting Diode
- Uses organic compounds that emit light when electric current is recieved.
- Thin and lightweight
- High contrast
- No backlight allows true black
- Inverter
- Turn DC into AC
- Digitizer
- Converts touch input into digital data
Cellular Standards
- PRL
- Preferred Roaming List
- Contains a list of towers that the phone will connect to
- 2G
- GSM
- Global System for Mobile Communications
- 90% of the global market
- EU Standard
- Used by AT&T and T-Mobile
- Multplexing
- CDMA
- Code Division Multiple Access
- Used by Verizon and Sprint
- Calls use unique codes
- 3G
- Introduced in 1998
- Better connectivity enabled new functionality
- Several megabits per second
- HSPA
- EVDO
- 4G
- LTE
- Long Term Evolution
- Introduced in 2009
- Based on GSM and EDGE
- Supports 150 Mbps
- LTE Advanced
- Supports 300 Mbps
- 5G
- Introduced in 2019
- Supports 10 Gbps
- IoT impact
Module 2: Networking
Common Ports and Services
- FTP
- tcp/20 for data
- tcp/21 for control
- SSH
- tcp/22
- Telnet
- tcp/23
- SMTP
- tcp/25
- Server to Server
- DNS
- udp/53
- DHCP
- udp/67
- udp/68
- HTTP
- tcp/80
- POP3
- tcp/110
- Server to one client
- IMAP
- tcp/143
- Server to multiple clients
- HTTPS
- tcp/443
- SMB
- tcp/445
- NetBIOS
- tcp/137 for name services, registration, removal by name
- tcp/139 for session services and data transfer
- SNMP
- udp/161 for queries/metrics/management
- udp/162 for responses/traps/alerts
- V1
- Structured Table
- Cleartext
- V2
- Enhanced data types
- Bulk Transfer
- Cleartext
- V3
- Authentication
- Encryption
- LDAP
- tcp/389
- RDP
- tcp/3389
Network Devices
- Routers
- Connects networks
- Forward packets based on IP
- Layer 3
- Switches
- Forward packets based on Layer 2 address
- Multilayer switch includes router functionality
- Unmanaged Switches
- Plug and play
- Fixed Configuration
- Cheap
- Managed Switches
- Supports VLANs
- Traffic Prioritization
- SPT redundancy
- Port mirroring
- SNMP
- Hub
- Connects devices
- Repeats all traffic to all ports
- Patch Panels
- Connects cables to switches
- Keeps cables organized
- Power over Ethernet
- POE
- IEEE 802.3af - 2003
- 15.4W DC, 350mA max current
- POE+
- IEEE 802.3at - 2009
- 25.5W DC, 600mA max current
- POE++
- IEEE 802.3bt - 2018
- 51W (Type 3), 600mA max current
- 71.3W (Type 4), 960mA max current
- PoE with 10GBASE-T
- ONT
- Optical Network Terminal
Network Tools
- Cable Crimper
- Strips, cuts, and crimps cables
- WiFi Analyzer
- Identifies errors and interference
- Tone Generator
- Identifies cable runs using analog sound
- Punchdown Tool
- Punches down wires into patch panels
- Cable Tester
- Tests for continuity
- Loopback Plug
- Useful for testing physical ports
- Taps and Port Mirrors
- Used to monitor and intercept traffic
Software Defined Networking
- Split the network into 3 layers
- Control Plane
- Data Plane
- Management Plane
- Control Plane
- Routing tables
- Session tables
- NAT tables
- Data Plane
- Process network frames and packets
- Forward packets
- Management Plane
- Configuration
- Monitoring
Wireless Network Standards
- 802.11a
- 1999
- 5GHz
- 54Mbps
- 802.11b
- 1999
- 2.4GHz
- 11Mbps
- 802.11g
- 2003
- 2.4GHz
- 54Mbps
- 802.11n (WiFi 4)
- 2009
- 2.4GHz and 5GHz
- 40MHz channel widths
- 150Mbps per MIMO stream
- 600Mbps
- 802.11ac (WiFi 5)
- 2013
- 5GHz
- 160MHz channel widths
- 867Mbps per MIMO stream
- 6.9Gbps
- Eight EU-MIMO downlink streams
- 802.11ax (WiFi 6)
- 2021
- 2.4GHz and 5GHz
- 20, 40, 80, 160MHz channel widths
- 1.2Gbps per MIMO stream
- 9.6Gbps
- Eight bidirectional Multi-User MIMO (MU-MIMO) streams
- Orthogonal Frequency Division Multiple Access (OFDMA)
WiFi Channels
- 2.4GHz
- 1-11, in the US and Can
- 1-13, in the EU
- 1-14, in Japan
- 1, 6, 11 are the most common
- b, g, n, and ax
- 5GHz
- Not as effective at penetrating walls
- a, n, ac, and ax
Assigning IP Addresses
- DHCP
- Replaced BOOTP in 1997
- BOOTP was Introduced in 1993
- APIPA
- Automatic Private IP Addressing
- IPs are assigned when DHCP is not available
- 169.254.0.0/16
DNS
- Address Records
- A
- IPv4
- AAAA
- IPv6
- MX Records
- Mail Exchanger
- SPF
- Sender Policy Framework
- Prevents spoofing
- DKIM
- Domain Keys Identified Mail
- Digitally sign outgoing mail
- DMARC
- Domain-based Message Authentication, Reporting, and Conformance
- Combines SPF and DKIM
Internet Connection Types
- DSL
- Direct Subscriber Line
- Uses existing copper telephone lines
- CO (Central Office) - CPE (Customer Premises Equipment)
- 200Mbps/DOWN, 20Mbps/UP
- Cable
- Broadband
- 50Mbps to 1Gbps
- Uses insulated and shielded coaxial cable
- DOCSIS
- Data Over Cable Service Interface Specification
- Fiber
- Higher cost than copper
- Uses glass or plastic surrounded by a protective coating to transmit light.
- SONET
- Synchronous Optical Network
- Satellite
- Uses a satellite dish to receive signals from a satellite in orbit
- High cost
- Good for remote locations
- Cellular
- Uses radio waves sent from a cell towers that are placed in a way to divide the land into cells
- WISP
- Wireless Internet Service Provider
- Need an antenna
Module 3: Hardware
Network Cables
- Twisted Pair
- Cat 5
- 1000Base-T
- 100 meters
- Cat 5e
- 1000Base-T
- 100 meters
- Enhanced
- Cat 6
- 10GBASE-T
- Unshielded: 55 meters
- Shielded: 100 meters
- Cat 6a
- 10GBASE-T
- 100 meters
- Augmented
- S
- Braided Shielding
- F
- Foil Shielding
- U
- Unshielded
- Coaxial
- RG-6 used in TV cable
- Plenum-rated Cable
- Fire resistant
- Flourinated Ethylene Polymer (FEP) or Polyvinyl Chloride (PVC)
- Optical Fiber
- No electrical interference, difficult to monitor or tap
- Single-mode
- Short-Range; 2km
- May use LEDs or other inexpensive light sources
- Multimode
- Long-Range; 100km
- Uses lasers
568A and 568B
- 568A
- White/Green
- Green
- White/Orange
- Blue
- White/Blue
- Orange
- White/Brown
- Brown
- 568B
- White/Orange
- Orange
- White/Green
- Blue
- White/Blue
- Green
- White/Brown
- Brown
Peripheral Cables
- USB
- Universal Serial Bus
- USB 1.0 - 1.5Mbps
- USB 1.1 - 12Mbps
- USB 2.0 - 480Mbps
- USB 3.0 - 5Gbps
- USB 3.1 - 10Gbps
- USB 3.2 - 20Gbps
- USB 3.2 Gen 2x2 - 40Gbps
- USB 4.0 - 40Gbps
- DB-9
- Serial
- Commonly used as a console port
- IDE
- Integrated Drive Electronics
- Parallel
- Used for hard drives and optical drives
- 40-pin
Video Cables
- VGA
- Video Graphics Array
- DE-15
- 15-pin D-Sub
- Blue color
- Analog
- Degrades after 5 to 10 meters
- DVI
- Digital Visual Interface
- Single Link
- 3.7 Gbps (HDTV at 60 fps)
- Dual Link
- 7.4Gps (HDTV at 85 fps)
- No audio
- DVI-A
- Analog
- DVI-D
- Digital
- DVI-I
- Integrated
- Can be analog or digital
- HDMI
- High-Definition Multimedia Interface
- All digital
- 19-pin
- Audio and video
- Degrades around 20 meters
- DisplayPort
- Information is sent in packets
- Compatible with HDMI and DVI
- Video and Audio
SATA
- Serial Advanced Technology Attachment
- Revision 1.0 - 1.5 Gbps
- Revision 2.0 - 3.0 Gbps
- Revision 3.0 - 6.0 Gbps
- Revision 3.2 - 16.0 Gbps
- Uses a 7-pin connector for data
- Uses a 15-pin connector for power
- Commonly used for storage devices
SCSI
- Small Computer Systems Interface
- Some configuration is done by the SCSI
Connectors
- RJ-11
- Telephone or DSL
- 6P2C
- Used for analog phone lines
- RJ-45
- 8P8C
- Commonly used for Ethernet
- RS-232
- Versatile
- DE-9
- DB-25
- It has the two twist things
- BNC
- Bayonet Neill-Concelman
- Used for coaxial cable
- Twist-lock
- F-Connector
- Coaxial
- Associated with Cable
- Fiber Connectors
- ST
- Straight Tip
- It has the extended tip
- SC
- Subscriber Connector
- Square
- LC
- Latching/Local Connector
- Often comes in a pair
Memory
- DIMM
- Dual Inline Memory Module
- Used for desktops
- SODIMM
- Small Outline DIMM
- Used for laptops
- DDR
- Double Data Rate
- SDRAM
- Synchronous Dynamic Random Access Memory
- Parity Bit
- In a set of 8 bits, one bit is used to check the other 7 bits
- It checks if there is an even or odd number of 1s, if odd the parity bit will equal one. If even, the parity bit will remain zero
- ECC
- Error Correcting Code
- High Integrity
Storage
- AHCI vs NVMe
- AHCI
- Advanced Host Controller Interface
- Move data from the hard drive to RAM
- Designed for hard drives
- NVMe
- Non-Volatile Memory Express
- Move data from the hard drive to RAM
- Uses PCIe
- Designed for SSDs
- M.2 Interface
- B-Key
- M-Key
RAID
- Redundant Array of Independent Disks
- RAID 0
- Striping
- Fastest
- Least reliable, no redundancy
- Does not increase capacity
- RAID 1
- Mirroring
- Slowest
- High redundancy
- Requires two drives
- RAID 5
- Striping with parity
- Fast
- Reliable
- Requires 3 or more drives
- RAID 10
- Striping with mirroring
- The speed of striping and the reliability of mirroring
- Requires 4 or more drives
Motherboards
- Form Factor
- ATX
- Best used in servers or desktops
- Standardised in 1995
- 20pin or 24pin power connector
- 8pin or 4pin CPU power connector
- Micro ATX
- Commonly used in small desktops
- Same as ATX but smaller
- Uses a 20pin power connector
- ITX
- Low power
- Small
- Compatible with ATX screws
- Useful for single-purpose computers, such as a media center
- Expansion Slots
- Computer Bus
- Sends data between devices
- Expansion Bus
- Connects the motherboard to the expansion cards
- Width of the bus determines the speed of the data transfer
- Clock rate is the speed of the bus
- PCI
- Peripheral Component Interconnect
- The PCI bus is a type of expansion bus
- The PCI slot provides power to cards
- 32-bit is shorter in length and has less pins than 64-bit pci card/slot
- PCIe
- Peripheral Component Interconnect Express
- Replacement for PCI, PCI-X and AGP
- Communicates serially using serial lanes (serial experiments lain?)
- Used for GPUs, RAID controllers, network cards, sound cards, etc
- PCIe x1
- 1 lane
- 1.5GB/s
- Network Cards
- PCIe x4
- 4 lanes
- 6GB/s
- PCIe x8
- 8 lanes
- 12GB/s
- PCIe x16
- 16 lanes
- 24GB/s
- Graphics Cards
- Riser Card
- Allows cards to be placed in different orientations
- Connectors
- CPU Socket
- Not an easy task to replace
- ZIF Socket
- Zero Insertion Force
- Used for CPUs
- Has lots of holes for Pin Grid Array (PGA) CPUs
- LGA Socket
- Land Grid Array
- Reverse of PGA
- Storage Connectors
- SATA
- PATA
- Uses IDE slot
BIOS
- Navigating to BIOS Settings
- Del, F1, F2, CTRL-S, CTRL-ALT-S
- Hold shift when pressing restart in Windows
- UEFI Secure Boot
- Verifies the bootloader by checking the signature
- TPM
- Trusted Platform Module
- Crypto processor
- HSM
- Hardware Security Module
- Crypto Hardware, Key Backup, Crypto Accelerator
- CMOS
- Complementary Metal Oxide Semiconductor
- Stores BIOS settings
- Uses a battery to keep settings when the computer is off
- Modern systems use a flash memory chip instead
CPU technologies
- ARM
- Advanced RISC Machine
- Power efficient
- Simpler instruction set
- Used in mobile and IoT devices
- Multithreading
- HTT
- One CPU acts like two
- Usually sees a performance increase of 15-30%
- Most modern OS support this
- Virtualization
- Intel VT-x
- AMD-V
Computer Power
- Always disconnect a device when working on it
- If a device stores a charge in a capacitor, it will still have power even when disconnected
- Power Supply
- Converts 120V AC or 240V AC to 3.3V DC, 5V DC, 12V DC
- Amp, Watt, Volt, Ohm
- Amp = Current
- How much charge is flowing through a circuit
- The diameter of the hose
- Volt = Voltage
- Electrical pressure
- How open the faucet is
- Watt = Power
- How much energy is being used
- Watt = Volt * Amp
- Ohm = Resistance
- How much resistance there is to the flow of electricity
- Ohm = Volt / Amp
- Current
- AC
- Alternating Current
- Current that changes direction
- US/Canada use 120V AC, 60Hz
- Europe uses 240V AC, 50Hz
- DC
- Direct Current
- Current that flows in one direction
- Ground
- Electrical current flows to ground
- Ground is a conductor
- Ground is a reference point
- Power Supply Output
- +12V
- PCIe adapters, hard drives, optical drives, fans
- +5V
- Some motherboard components
- +3.3V
- M.2 SSDs, RAM slots, logic circuits
- +5VSB
- Standby voltage
- 12V
- Integrated LAN
- Older serial ports
- -5V
- ISA slots
- Not used anymore
Multifunction Devices
- Printers
- Laser
- Processing in memory
- Charge drum
- Exposing with laser
- Add toner to charged areas
- Transfer to paper
- Fuse with heat
- Remove excess toner
- Pros
- Fast
- High quality
- Cons
- Complex
- Moving Parts
- Image Drum
- Contains the toner
- Drum rotates and applies toner to the paper
- Image is drawn on the drum by the laser
- Fuser Assembly
- Melt plastic toner using heat and pressure
- Transfer Belt
- Image is transferred from all cartridges to the single belt
- Cyan, Magenta, Yellow, Black
- Pickup Roller
- Rolls the paper through the printer
- Separation Pad
- Pulls one sheet from the paper tray
- Duplexing assembly
- Prints on both sides of the paper
- Maintenance
- Replace toner, low does not mean empty
- Toner may contain the OPC drum, sensitive to light
- Printers page counter will tell you when to perform maintenance
- Clean the printer routinely, the toner and paper dust spreads. Stick to the manufacturers recommendations
- Inkjet
- Pros
- Low cost tech
- Quiet
- High resolution
- Cons
- Ink is proprietary and expensive
- Ink Fades
- Print head clogs
- Ink Cartridge
- CMYK
- Place droplets of ink on the paper
- Print Head
- Occasionally the print head will be integrated into the ink cartridge
- Print head may clog
- Feed Roller
- Rolls the paper through the printer
- Carriage and Belt
- Carriage moves the print head back and forth
- Belt moves the carriage
- Maintenance
- Replace ink cartridges when they are empty, empty cartridge can be recycled.
- Jams are inevitable
- Calibrate the printer routinely
- Thermal
- Pros
- Very Quiet
- No ink
- Cons
- Sensitive to light and heat
- Thermal Paper
- Paper changes color when heated
- Feed Assembly
- Rolls the paper through the printer
- Heating element
- Heats the paper
- Maintenance
- Thermal paper measurements differ
- A cleaning pen and IPA can be used to clean the heating element
- Impact
- Pros
- Low cost per page
- Good for multiple copies
- Cons
- Low resolution
- Noisy
- Print Head
- Moves back and forth, pressing a ribbon against the paper
- Ribbon
- One ribbon
- Proprietary size
- Maintenance
- Replace ribbon when ink lightens
- Print head can be replaced when the ribbon is replaced
- 3D
- Filament
- FDM
- Fused Deposition Modeling
- More Common than SLA
- Uses a heated nozzle to melt plastic
- SLA
- Stereolithography
- Uses a laser to cure a liquid resin
- Resin is hazardous
Module 4: Virtualization and Cloud Computing
Cloud Deployment Models
- Public Cloud
- Resources are shared with the public
- Private Cloud
- Resources are shared with a single organization
- Hybrid Cloud
- A mix of public and private cloud
Cloud Service Models
- Software as a Service (SaaS)
- Software is hosted by the cloud provider
- Users access the software through a web browser
- Examples: Google Docs, Office 365
- Platform as a Service (PaaS)
- Platform is hosted by the cloud provider
- Users can develop and deploy their own applications
- Examples: Google App Engine
- Infrastructure as a Service (IaaS)
- Infrastructure is hosted by the cloud provider
- Users can deploy their own applications
- Examples: Amazon Web Services
Virtualization
- Hypervisor
- Software that creates and runs virtual machines
- Type 1: Runs directly on the hardware
- Examples: VMware ESXi, Microsoft Hyper-V
- Type 2: Runs on top of an operating system
- Examples: VMware Workstation, VirtualBox
- Requirements
- AMD-V or Intel VT-x
- Security Concerns
- VM escape
- VM escapes the hypervisor and gains access to the host
- Often is done using shared memory, clipboard, drives, etc
- VM sprawl
- VMs become unmanageable
Module 5: Hardware and Network Troubleshooting
Troubleshooting
- Identify the problem
- Establish a theory of probable cause
- Test the theory
- Create a plan to fix the problem
- Implement the plan
- Verify the problem is fixed
- Document the solution
Hardware Troubleshooting
- POST
- Power On Self Test
- Test major components before boot
- Beep codes
- POST and Boot
- Blank screen on boot
- Any beeps?
- Bad video, bad RAM, bad cpu, bios misconfiguration
- BIOS time and settings
- Maintained with the motherboard battery
- Boots in incorrect order
- Check boot order in BIOS
- Does the selected device have a valid OS?
- Is the device connected?
- Crash Screen
- Blue Screen of Death (BSOD)
- Windows
- Driver issue
- Use last known good configuration
- Use safe mode
- Spinning ball of death (SBOD)
- Mac
- App bug, bad hardware, disk issue
- Restart
- Check logs
- Black Screen
- Is the monitor plugged in and turned on?
- Is the monitor using the correct input?
- Try another monitor
- If no video after windows loads, try vga mode (f8)
- No power
- Use a multimeter to check for power
- Is anything powered on? Fans?
- Check PSU output
- On a laptop, check the power brick
- On a desktop, check the power switch
- If the laptop is plugged in and working but shuts off when unplugged, the battery is bad or not plugged into board
- Sluggish performance
- Task manager, update, disk space, powersaving, virus
- Overheating
- Check fans, vents, heat sink, bad components
- Use a can of compressed air to clean out dust
- cpuid.com
- Intermittent Shutdown
- Heat, Hardware
- Eliminate working parts
- App crashes
- Look for error message, check event logs, check the reliabiltiy monitor
- Grinding noises
- Bad hard drive, bad fan, blown capacitor, bad power supply
- Lockups
- Check for responses, try shortcuts, update drivers and software, low resources
- Continuous Reboot
- F8
Storage Troubleshooting
- Symptoms
- R/W errors
- Slow performance
- Clicking/Grinding noises
- Disk Failures
- Backups, Check for loose/damaged cables
- Check for overheating, power supply, run hardware diagnostics
- RAID Failures
- RAID not found
- Faulty controller
- RAID stops working
- Check the console, every RAID is different
- RAID failure conditions
- RAID 0: 1 drive failure
- RAID 1: 1 must remain operational
- RAID 5: All drives must remain operational but one
- RAID 10: All but one from each set of mirrors
Video Troubleshooting
- Native Resolution
- Check the monitor manual
- Burn-in
- Static images on the screen
- Use a white page for a while
- Dead Pixels
- Pixel is always black
- Factory defect
- Flashing Screen
- Replace cable
- Check display settings
- Projector Problems
- Check the lamp
- Relatively expensive to replace
- May be hot
- Check the filter
- Check the fan
Mobile Troubleshooting
- Battery
- Check battery usage
- Aging batteries need to be replaced
- Swollen battery
- Buildup of gas
- Fire risk
- Dispose and replace
- Liquid Damage
- LCI
- Liquid Contact Indicator
- Power phone down, remove case
- Place in silica gel
- Leave it alone for at least a day
- Power on
- Digitizer
- Touch screen not working
- Check for cracks
- Reboot
Networking Troubleshooting
- Is there a link light?
- Ping loopback
- Ping gateway
- Ping local device
- Ping 8.8.8.8
- Tracert