CompTIA A+ Core 1 220-1201 Study Guide

// Exam Domain Weights (220-1201)

1. Mobile Devices

15%

2. Networking

20%

3. Hardware

25%

4. Virtualization & Cloud Computing

11%

5. Hardware & Network Troubleshooting

29%

IT Fundamentals & Troubleshooting Methodology

Domain 5

The Role of an IT Specialist

Troubleshoot and resolve hardware, software, and network issues.
Set up and configure new systems and peripherals.
Provide ongoing support for existing systems and end users.
Key skills: problem-solving, communication, documentation, and technical knowledge.

CompTIA Troubleshooting Methodology — 7 Steps

Identify the problem. Question the user. Identify any recent changes to hardware, software, or environment. Review event logs. Determine scope — one user or many?

Establish a theory of probable cause. Consider possible causes, start simple (is it plugged in?). Question the obvious before assuming complexity.

Test the theory. Physical inspection, reproduce the problem, check documentation. If theory confirmed → move on. If not → establish new theory or escalate.

Establish a plan of action. Assess cost, time, resources, and impact. Seek authorization from the appropriate person. Adhere to policies and procedures.

Implement the solution. Choose best time (off-hours if possible). Notify impacted users. Follow vendor instructions. Make one change at a time.

Verify full system functionality. Confirm the fix works. Implement preventive measures so the issue doesn't recur.

Document findings, actions, and outcomes. Record what the problem was, what caused it, what fixed it, and what was done to prevent recurrence.

This is your SMEAC for tech problems — same structured approach every time. The exam will give you scenarios and ask which step comes next. Know the order cold. "Test the theory" always comes before "establish a plan of action."

The exam frequently asks what to do when a theory is NOT confirmed — the answer is to establish a new theory or escalate. Never skip to implementation without a confirmed theory.

Cables, Connectors & Interfaces

Domain 3

USB Standards

Standard	Year	Max Speed	Connector	Also Called
USB 1.1	1998	12 Mbps	Type-A, Type-B	Full Speed
USB 2.0	2000	480 Mbps	Type-A, Mini, Micro	Hi-Speed
USB 3.0	2008	5 Gbps	Type-A (blue), Type-C	USB 3.1 Gen 1 / SuperSpeed
USB 3.1	2013	10 Gbps	Type-C	USB 3.1 Gen 2 / SuperSpeed+
USB 3.2	2017	20 Gbps	Type-C	Gen 2×2
USB4	2019	40 Gbps	Type-C only	Unified with Thunderbolt 3

USB 3.0 ports are blue. USB 3.1 Gen 1 = USB 3.0 (5 Gbps). USB 3.1 Gen 2 = 10 Gbps. The naming is deliberately confusing — know what each speed maps to.

USB Connector Types

Type-ARectangular. Standard host/PC side connector. On nearly every computer. USB 1.1 through USB 3.2. Type-BSquare. Device side for large peripherals (printers, scanners). Less common now. Mini-BSmaller than Type-B. Older cameras and devices. Largely obsolete. Micro-BFlat, small. Was the standard for Android phones. Still common on budget devices. Type-CReversible — no wrong way to plug in. Used for USB 3.1+, USB4, and Thunderbolt 3/4/5. Single connector for power, data, and video.

Thunderbolt Interface

Version	Speed	Connector	Notes
TB 1	10 Gbps	Mini DisplayPort	Compatible with DisplayPort devices.
TB 2	20 Gbps	Mini DisplayPort	Aggregates two TB1 channels.
TB 3	40 Gbps	USB-C	Supports 2×4K displays. Unified with USB4.
TB 4	40 Gbps	USB-C	Stricter certification than TB3. Up to 4 daisy-chained devices.
TB 5	80+ Gbps	USB-C	Latest generation. Supports 3×4K or 1×8K displays.

Thunderbolt ports are identified by a lightning bolt icon (⚡). TB3 and TB4 use USB-C connectors but are NOT the same as USB-C. A Thunderbolt device will work in a USB-C port at USB speeds only, not at Thunderbolt speeds.

Video Connectors

Connector	Signal	Audio	Key Facts
VGA	Analog	No	15-pin DB-15 (HD-15). Legacy. Still common on projectors and older monitors. Cannot carry digital signal natively.
DVI-A	Analog only	No	Analog DVI. Can connect to VGA via passive adapter.
DVI-D	Digital only	No	Digital DVI. Single-link (3.96 Gbps) or Dual-link (7.92 Gbps).
DVI-I	Both	No	Integrated — carries both analog and digital. Most flexible DVI type.
HDMI	Digital	Yes	Carries audio + video on one cable. Consumer standard for TVs and monitors. Supports HDR, ARC, CEC. Multiple versions (1.4 = 4K@30Hz, 2.0 = 4K@60Hz, 2.1 = 8K).
DisplayPort	Digital	Yes	PC/professional standard. Supports MST (daisy-chain multiple displays from one port). Adaptive sync (G-Sync/FreeSync). Mini DisplayPort = same signal, smaller connector (used on MacBooks, Thunderbolt 1/2).

DVI-I carries both analog and digital — it can connect to VGA (analog) or DVI-D (digital). DVI-D is digital only — cannot connect to VGA without an active adapter. VGA to DVI-D requires an active converter, not a passive adapter.

Storage Interface Cables

SATA Data (7-pin)L-shaped. Connects HDD/SSD to motherboard SATA port. Max 6 Gbps (SATA III). Max cable length 1 meter. SATA Power (15-pin)From PSU to drive. Wider than data cable. Provides 3.3V, 5V, and 12V. eSATAExternal SATA. For external drives. Same speed as internal SATA (6 Gbps). Does NOT carry power — external drive needs separate power source. M.2Small form-factor slot directly on motherboard. Supports both SATA (slower) and NVMe/PCIe (fast). Key types: M key (NVMe), B key (SATA/NVMe), B+M key (either). Check motherboard specs — not all M.2 slots support NVMe. Molex (4-pin)Legacy power connector for IDE drives, fans, older devices. Colors: Red = 5V, Yellow = 12V, Black = Ground. Being replaced by SATA power. IDE/PATALegacy 40/80-pin ribbon cable. Used before SATA. Supports two drives per cable (master/slave). Obsolete in modern systems.

Adapter Cables

Active AdapterContains circuitry to convert signal format (e.g., digital to analog). Required when signal type changes. Example: DisplayPort to VGA, HDMI to VGA. Passive AdapterConverts connector shape only — no signal conversion. Signal type must be compatible. Example: Mini HDMI to HDMI, Mini DisplayPort to DisplayPort.

Active vs Passive is a frequent exam topic. If converting from digital to analog (HDMI→VGA, DP→VGA) you MUST use an active adapter. Passive adapters only work between compatible signal types (digital-to-digital).

Motherboards

Domain 3

Form Factors

Form Factor	Dimensions	PCIe Slots	Use Case
ATX	12" × 9.6"	Up to 7	Standard desktop tower. Most expandable.
Micro-ATX (mATX)	9.6" × 9.6"	Up to 4	Budget/compact builds. Fits ATX cases too.
Mini-ITX	6.7" × 6.7"	1	Small form factor, HTPC, NUC-style builds.
E-ATX	12" × 13"	Up to 8	Workstation/server. Requires E-ATX case.

Smaller form factors (mATX, Mini-ITX) fit in larger cases but larger form factors do NOT fit in smaller cases. A Mini-ITX board fits in an ATX case; an ATX board does NOT fit in a Mini-ITX case.

Key Motherboard Components

CPU SocketIntel uses LGA (Land Grid Array — pins on socket). AMD uses PGA (Pin Grid Array — pins on CPU) for AM4; AM5 uses LGA. Socket type determines CPU compatibility. Never mix socket types. ZIF SocketZero Insertion Force. Lever mechanism allows CPU to drop in with no force — prevents bent pins. Most modern CPU sockets use ZIF. DIMM SlotsHolds RAM. Color-coded pairs for dual-channel. Install in matched pairs in same-colored slots for dual-channel operation. PCIe Slotsx16 for GPUs. x4/x8 for capture cards, NVMe adapters, NICs. x1 for basic expansion cards. A smaller card fits in a larger slot (runs at card's max speed). M.2 SlotConnects NVMe SSDs directly to PCIe bus. Much faster than SATA. Some slots support only SATA-mode M.2 — check specs before buying an NVMe drive. SATA PortsL-shaped ports. Typically 4–8 per board. Connect HDDs, SSDs, and optical drives. 24-pin ATX (P1)Main motherboard power connector from PSU. Must be fully seated — partial connection causes boot failure. 4/8-pin EPSCPU auxiliary power. Near the CPU socket. Required for system to POST — often forgotten during builds. Front Panel HeadersPower button, reset button, HDD activity LED, power LED, USB 2.0, USB 3.0, front audio. Tiny 1- and 2-pin connectors. Check motherboard manual for exact pin layout. CMOS BatteryCR2032 lithium coin cell. Maintains BIOS/UEFI settings (date, time, boot order) when system is unpowered. When it dies: system loses date/time on every power cycle. Replace and re-enter settings. ChipsetManages communication between CPU, RAM, storage, and PCIe devices. Northbridge (now integrated into CPU) handles high-speed connections. Southbridge handles slower I/O (USB, SATA, audio). I/O ShieldMetal plate installed in case before motherboard. Covers rear port cutout. Must match motherboard I/O layout — comes in the motherboard box.

Expansion Cards

GPU (Video Card)Dedicated graphics processor with its own VRAM. Uses PCIe x16. Required for gaming, CAD, video editing. Has DisplayPort, HDMI, DVI outputs. Needs 6/8-pin PCIe power from PSU for high-end cards. Sound CardDedicated audio processing. Uses PCIe x1. Improves audio quality over integrated audio. Provides dedicated DAC/ADC. Capture CardCaptures video/audio input from external sources (cameras, game consoles). Used for streaming and recording. Internal (PCIe) or external (USB) versions. NICNetwork Interface Card. Adds or upgrades network connectivity. Copper (RJ-45) or fiber (SFP). Can add 10G capability to a system with only 1G integrated NIC. Riser CardExtends PCIe slot to allow card installation in a different orientation. Common in small form factor cases and servers.

Motherboard Installation Order

Review documentation — confirm form factor compatibility with case, CPU socket, RAM type.

Install I/O shield into case cutout (snap in before motherboard goes in).

Install standoffs into case at correct positions for form factor.

Pre-install CPU, CPU cooler, and RAM onto motherboard before placing it in case (easier to work on flat surface).

Align motherboard over standoffs and I/O shield. Secure with screws — do not overtighten.

Connect all power connectors (24-pin ATX, 4/8-pin CPU, PCIe power for GPU).

Connect data cables (SATA) and front panel headers. Perform cable management.

Power Supplies & Cooling

Domain 3

Power Supply Units (PSU)

Converts AC wall power (110V/220V) to regulated low-voltage DC for computer components. Outputs: 3.3V (logic circuits), 5V (legacy drives, USB), 12V (motors, CPU, GPU).

WattageTotal continuous power output. Size for peak load plus 20–30% headroom. Undersized PSU = random crashes and instability under load. 80 PLUS RatingEfficiency certification. 80 PLUS (80%) → Bronze (82%) → Silver (85%) → Gold (87%) → Platinum (90%) → Titanium (94%). Higher = less heat, lower electricity cost. ModularAll cables detachable. Best airflow and cable management. Most expensive. Semi-ModularEssential cables (24-pin, EPS) fixed. Others detachable. Balance of cost and flexibility. Non-ModularAll cables permanently attached. Cheapest. Requires cable management or results in clutter. Redundant PSUTwo PSUs in one server/workstation. If one fails, the other takes over. Hot-swappable. Enterprise/server standard.

PSU Connectors

Connector	Pins	Purpose	Notes
ATX Main (P1)	24-pin	Main motherboard power	Backward compatible with 20-pin boards via 20+4 design.
EPS / CPU	4 or 8-pin	CPU power	Near CPU socket. Required — system won't POST without it.
PCIe Power	6 or 8-pin	GPU power	6-pin = 75W, 8-pin = 150W. High-end GPUs need one or two.
SATA Power	15-pin	SATA drives	Provides 3.3V, 5V, and 12V. Daisy-chained on one cable.
Molex	4-pin	Legacy drives, fans, adapters	Red=5V, Yellow=12V, Black=Ground. Being phased out.
Mini-Molex / Berg	4-pin	Floppy drives	Legacy. Essentially obsolete.

Cooling Systems

Heat SinkCopper or aluminum finned block mounted on CPU. Draws heat away from die via conduction, dissipates into air via convection. Copper conducts heat better; aluminum is lighter and cheaper. Thermal Paste (TIM)Thermal Interface Material. Fills microscopic air gaps between CPU die and heat sink base. Critical for heat transfer — missing or dried-out paste = overheating. Apply a small pea-sized amount in center (spreads under pressure). CPU Fan (Active Air Cooling)Fan mounted on heat sink. Controlled by motherboard via PWM (Pulse Width Modulation) based on temperature. 4-pin PWM fan = variable speed. 3-pin = fixed or voltage-controlled. Case FansIntake fans at front/bottom pull cool air in. Exhaust fans at rear/top push hot air out. Balanced airflow = optimal cooling. More exhaust than intake = negative pressure (dust in). More intake = positive pressure (dust filtered). Liquid Cooling (AIO)All-in-One liquid cooler. Water block on CPU, pump, tubing, radiator mounted to case. Quieter and more effective than air for high TDP CPUs. Radiator sizes: 120mm, 240mm, 360mm (more = more cooling). Custom LoopDIY liquid cooling with separate reservoir, pump, blocks, tubing, and radiator. Maximum cooling performance. Complex to build and maintain. Risk of leaks. Passive CoolingNo fans — relies purely on heat sink surface area and convection. Silent. Limited to low-power/low-TDP systems (NUCs, embedded systems, some NAS devices).

Never power on a CPU without thermal paste and a cooler attached — even briefly. A CPU without cooling can permanently damage itself within seconds of boot at full load.

Processors (CPUs)

Domain 3

CPU Architecture

x86 (32-bit)Legacy architecture. Limited to 4GB addressable RAM. Runs only 32-bit software. Still found on some embedded systems. x64 (64-bit)Current standard for PCs and servers. Theoretically addresses 16 exabytes of RAM. Runs both 32-bit and 64-bit software. ARMRISC-based. Designed for mobile and embedded (phones, tablets, IoT). Low power consumption. SoC (System on Chip) — CPU, GPU, RAM controller integrated on one die. Cannot natively run x86/x64 software without emulation.

RISC vs CISC

RISC — Reduced Instruction Set Computing

Small, simple instruction set.
Each instruction executes in one clock cycle.
More instructions needed to complete tasks.
Lower power consumption.
Examples: ARM, MIPS, PowerPC.

CISC — Complex Instruction Set Computing

Large, complex instruction set.
Single instruction can execute complex tasks.
Fewer instructions needed.
Higher power consumption.
Examples: x86, x64 (Intel, AMD).

CPU Features

Multi-CoreMultiple independent processing cores on one physical die. Dual-core, quad-core, octa-core, etc. Each core can execute its own thread simultaneously. Hyper-Threading (Intel) / SMT (AMD)Simultaneous Multithreading. One physical core presents as two logical processors to the OS. Improves throughput on threaded workloads by up to 30%. Not the same as having two physical cores. Virtualization SupportIntel VT-x / AMD-V. Hardware-assisted virtualization. Required to run Type 1 or Type 2 hypervisors at full performance. Must be enabled in BIOS/UEFI — often disabled by default. Cache (L1/L2/L3)L1 = fastest, smallest, per-core (32–64KB). L2 = medium, per-core (256KB–1MB). L3 = largest, shared across all cores (8–64MB+). More cache = fewer slow RAM accesses. TDP (Thermal Design Power)Maximum sustained heat output in watts. Determines what cooler is required. A 65W TDP CPU needs a cooler rated for at least 65W. Clock Speed (GHz)Cycles per second. Higher = faster (within same architecture). Base clock = guaranteed speed. Boost clock = max speed under optimal conditions (temperature, power). Integrated Graphics (iGPU)GPU built into the CPU die. Uses shared system RAM. Sufficient for general computing and light media. Disabled or supplemental when a discrete GPU is present.

CPU Families

Intel	AMD	Use Case
Core i3	Ryzen 3	Entry-level / budget. Office work, light tasks.
Core i5	Ryzen 5	Mid-range / mainstream. Best value for most users.
Core i7	Ryzen 7	High performance. Gaming, content creation.
Core i9	Ryzen 9	Enthusiast / workstation. Maximum cores and cache.
Xeon	EPYC / Threadripper	Server and data center. ECC RAM support, high core counts, multi-socket.
Celeron / Pentium	Athlon	Budget / embedded. Basic computing tasks.

System Memory (RAM)

Domain 3

RAM Fundamentals

RAM (Random Access Memory) is volatile — loses all contents when power is removed. The CPU uses RAM to store actively accessed data and instructions for fast retrieval. More RAM = more applications can run simultaneously without swapping to disk.

DDR Generations

Generation	Speed Range	DIMM Pins	SO-DIMM Pins	Voltage	Status
DDR3	800–2133 MT/s	240	204	1.5V	Legacy
DDR4	2133–3200 MT/s	288	260	1.2V	Widely deployed
DDR5	4800+ MT/s	288	262	1.1V	Current / new systems

DDR generations are NOT interchangeable. Each has a different notch position, different pin count (DDR3 vs DDR4 both have 240/288 pins but DDR4 DIMM is 288), and different voltage. Installing the wrong generation physically cannot seat in the slot.

Memory Module Types

DIMMDual Inline Memory Module. Full-size desktop RAM. 64-bit data bus per module. SO-DIMMSmall Outline DIMM. Laptop and small form-factor systems. About half the length of a DIMM. Same electrical specifications, different physical size. Single-ChannelOne DIMM or mismatched DIMMs. 64-bit data path. Lower bandwidth. Dual-ChannelTwo matched DIMMs in paired slots (same color). 128-bit data path. Install in slots A2+B2 or A1+B1 — check motherboard manual for correct slots. Quad-ChannelFour matched DIMMs. 256-bit data path. Used in workstations and servers with high-bandwidth needs. ECC RAMError Correcting Code. Detects and corrects single-bit errors silently. Required in servers and mission-critical workstations. Requires ECC-capable CPU and motherboard. Not compatible with standard consumer boards. Registered (RDIMM)Has a register chip between the memory controller and DRAM. Allows more DIMMs per channel. Used in servers. Slightly higher latency than UDIMM. Unregistered (UDIMM)Standard consumer RAM. No register chip. Lower latency but limited to fewer DIMMs per channel.

Virtual Memory

When physical RAM is exhausted, the OS uses a portion of disk storage as an overflow — called the page file (Windows) or swap space (Linux). Virtual memory is dramatically slower than RAM (milliseconds vs nanoseconds). A system that frequently uses virtual memory needs more physical RAM. Symptom: slow performance with high disk activity.

If a system is sluggish with constant disk thrashing, the most cost-effective fix is adding more RAM. Virtual memory is a stopgap, not a solution.

Storage Devices

Domain 3

Storage Types

Type	Interface	Approx Speed	Pros	Cons
HDD	SATA	80–160 MB/s	Cheap per GB. High capacity.	Slow. Moving parts. Fragile (drops). Loud.
SSD (SATA)	SATA	~550 MB/s	No moving parts. Quiet. Durable. Fast vs HDD.	Limited by SATA interface. More expensive per GB than HDD.
SSD (NVMe)	PCIe/M.2	3,000–7,000 MB/s	Fastest available. Low latency.	Most expensive per GB. Can run hot without heatspreader.
Optane (Intel)	PCIe/M.2	High IOPS	Extremely low latency. Great for cache.	Discontinued. Limited capacity options.

HDD RPM Speeds5,400 RPM (5.5ms latency, archival/laptop), 7,200 RPM (4.2ms, standard desktop/NAS), 10,000 RPM (3ms, enterprise), 15,000 RPM (2ms, highest performance). SSD Wear LevelingFlash memory cells degrade with writes. Wear leveling distributes writes across all cells evenly to maximize lifespan. Managed by the SSD controller. SSD Endurance (TBW)Terabytes Written — manufacturer's rated total write endurance. A 600 TBW SSD can write 600TB before expected failure. Consumer SSDs: 150–600 TBW. Enterprise: 1,000+ TBW.

RAID Levels

RAID	Name	Min Drives	Fault Tolerance	Usable Space	Notes
RAID 0	Striping	2	None	100%	Fast. Any single drive failure = total data loss.
RAID 1	Mirroring	2	1 drive	50%	Exact copy. Fastest restore. Expensive per GB.
RAID 5	Stripe + Parity	3	1 drive	(N-1) drives	Most common enterprise. Parity distributed across all drives.
RAID 6	Double Parity	4	2 drives	(N-2) drives	Better protection. Recommended for large HDDs (long rebuild time).
RAID 10	Stripe of Mirrors	4	1 per mirror	50%	Best performance + redundancy. Expensive. Ideal for databases.

RAID is NOT a backup. RAID protects against drive failure but not against accidental deletion, ransomware, fire, or theft. Always maintain separate backups. RAID 0 has zero fault tolerance — it increases risk because losing ANY drive loses everything.

Removable Storage

USB Flash DrivePortable flash memory via USB. Widely used for data transfer and bootable media. External HDD/SSDDrive in enclosure with USB/eSATA connection. USB 3.0 or better for acceptable speed. SD CardSecure Digital. Full-size SD, miniSD, microSD. Speed classes: Class 10, UHS-I, UHS-II, V30, V60, V90 (video speed class). Optical (CD/DVD/Blu-ray)Data read/written via laser. CD=700MB, DVD=4.7–8.5GB, Blu-ray=25–50GB. Used for media distribution, archival. Largely replaced by USB and streaming. TapeMagnetic tape. Sequential access only (slow). Extremely cheap per TB. Used for long-term archival backup in enterprise. LTO is current standard.

BIOS/UEFI & Boot Process

Domain 3

BIOS vs UEFI

Feature	Legacy BIOS	UEFI
Interface	Text-only, keyboard only	Graphical, mouse support
Partition Table	MBR only (max 2TB, 4 primary partitions)	GPT (max 128 partitions, no practical size limit)
Boot Speed	Slower POST	Faster POST, supports fast boot
Secure Boot	No	Yes
Drive Support	Limited to MBR drives	Full NVMe and GPT drive support
Architecture	16-bit	32/64-bit
Network Boot	Basic PXE	Full PXE and HTTP boot support

Windows 11 requires UEFI with Secure Boot and a TPM 2.0 chip. If a system can't run Windows 11, check UEFI and TPM settings in the firmware first before assuming incompatible hardware.

Key BIOS/UEFI Settings

Boot OrderPriority list of devices to attempt boot from. Set USB or optical first for installs, HDD/SSD first for normal operation. Wrong boot order = "No boot device found" error when USB is plugged in. Secure BootVerifies OS bootloader is cryptographically signed by a trusted authority. Prevents unsigned/malicious OS from loading. Must disable for some Linux distros or custom boot scenarios. TPMTrusted Platform Module. Hardware chip (or firmware implementation — fTPM) that stores encryption keys. Required for BitLocker and Windows 11. Enable in UEFI before installing Windows. Supervisor/Setup PasswordRestricts access to UEFI settings. Protects against unauthorized firmware changes. Different from system/user password. User/System PasswordLocks the system at POST — must enter password before OS loads. Not the same as the Windows login password. Virtualization (VT-x/AMD-V)Must be enabled in UEFI for hypervisors to use hardware-assisted virtualization. Often disabled by default. Symptom if disabled: hypervisor errors or 64-bit VMs won't start. Fan SettingsControl fan speed curves — balanced, cool, quiet, fanless, custom. Custom = define temperature thresholds and fan speeds. XMP/EXPO ProfileEnables RAM to run at its rated speed (e.g., DDR4-3200 instead of default DDR4-2133). Must enable in UEFI — RAM ships at minimum JEDEC spec by default.

POST (Power-On Self-Test)

When the system receives power, the CPU executes POST — a firmware-level diagnostic that checks all critical hardware before attempting to boot an OS. POST checks: CPU, RAM, video card, storage controllers, keyboard. Results communicated via beep codes (before video) or on-screen codes (after video initializes).

Beep CodesPatterns of beeps indicate specific POST failures. Vary by BIOS manufacturer (AMI, Award, Phoenix). Common: 1 short = POST OK (some boards), 1 long + 2 short = video card failure (AMI). Always check motherboard documentation for specific codes. POST CardDiagnostic card that plugs into PCIe slot and displays POST codes as hexadecimal numbers. Useful when system won't POST at all and gives no beeps. No POSTSystem powers on but nothing happens. Check: power connectors (24-pin AND 4/8-pin CPU), RAM seating, GPU seating, CMOS clear. Try booting with minimal hardware (1 stick RAM, no GPU if iGPU available).

POST is like a pre-mission equipment check — you verify every piece of kit works before you step off. If something fails the check, you fix it before the mission, not during. A failed POST beep code tells you exactly which kit item is broken.

MBR vs GPT Partition Tables

MBR (Master Boot Record)Legacy partition scheme. Max 4 primary partitions (or 3 primary + 1 extended with logical partitions inside). Max 2TB drive size. Required for BIOS boot. First 512 bytes of disk contain boot code + partition table. GPT (GUID Partition Table)Modern scheme. Up to 128 partitions. No practical size limit. Required for drives >2TB. Required for UEFI boot. Stores backup partition table at end of disk for redundancy. Each partition has a GUID (Globally Unique Identifier).

Networking Hardware

Domain 2

Network Types

LANLocal Area Network. Single location. Connected by switches and cables. High speed (1G–10G typical). WANWide Area Network. Spans multiple locations. The Internet is the largest WAN. Lower speed than LAN, higher latency. WLANWireless LAN. Uses 802.11 standards (Wi-Fi). Connects devices wirelessly to a LAN via WAP. MANMetropolitan Area Network. Covers a city or campus. Larger than LAN, smaller than WAN. PANPersonal Area Network. Very short range. Bluetooth (~10m), NFC (~4cm). Connects personal devices. SANStorage Area Network. Dedicated high-speed network for storage access. Block-level access. iSCSI or Fibre Channel.

Network Devices

NICNetwork Interface Card. Physical connection to network. Every NIC has a unique 48-bit MAC address (burned in at manufacture). First 24 bits = OUI (vendor ID). Last 24 bits = device ID. HubLegacy Layer 1 device. Repeats signal out ALL ports. Creates one large collision domain. No intelligence. Replaced by switches. Do not use in modern networks. SwitchLayer 2 device. Forwards frames using MAC address table. One collision domain per port. Builds MAC table by learning source MACs. Sends unknown MACs to all ports (flooding) until learned. RouterLayer 3 device. Routes packets between networks using IP addresses and routing table. Separates broadcast domains. Connects LAN to WAN (internet). WAPWireless Access Point. Bridges wireless clients to the wired LAN. Manages 802.11 wireless connections. Not a router — WAPs don't route; they bridge. Patch PanelTerminates structured cabling from wall outlets. Provides organized connection point to switch via short patch cords. Allows easy moves, adds, and changes without re-running cable. FirewallFilters traffic based on rules (ACLs). Stateful inspection tracks connection state. Can be hardware appliance or software. First line of defense at network perimeter. Proxy ServerIntermediary for web requests. Caches content, filters URLs, logs activity. Clients send requests to proxy; proxy fetches on their behalf. Hides internal IP addresses. Load BalancerDistributes incoming traffic across multiple servers. Prevents any single server from being overwhelmed. Round-robin, least connections, or weighted distribution methods. UTMUnified Threat Management. Combines firewall, IDS/IPS, antivirus, spam filter, VPN in one appliance. Common in SMB environments.

Managed vs Unmanaged Switches

Unmanaged Switch

Plug and play — no configuration needed or possible.
No VLANs, no port security, no SNMP monitoring.
Cheap. Suitable for home and small offices.
No visibility into traffic or port status.

Managed Switch

Fully configurable via CLI, web GUI, or SNMP.
Supports VLANs, STP, port security, QoS, port mirroring.
SNMP monitoring for centralized network management.
Required for enterprise environments.

Power over Ethernet (PoE)

Standard	Max Power	Common Name	Use Cases
802.3af	15.4W delivered / 12.95W at device	PoE (Type 1)	VoIP phones, basic IP cameras, WAPs.
802.3at	30W delivered / 25.5W at device	PoE+ (Type 2)	High-power WAPs, PTZ cameras, small switches.
802.3bt	60W (Type 3) / 100W (Type 4)	PoE++ / 4PPoE	Laptops, TVs, large PTZ cameras, mini PCs.

PoE SwitchSwitch with PoE built in. Powers devices on the same cable as data. Simplest solution — one cable per device. PoE InjectorAdds PoE to a single port of a non-PoE switch. Sits between switch and device. One injector per device. PoE SplitterTakes a PoE connection and splits it into separate data and power outputs. Used for devices without built-in PoE.

PoE budget: a 48-port PoE switch may have a total PoE budget of 370W. If all 48 ports draw 802.3af (15.4W each = 739W total), it will not power all devices simultaneously. Calculate total PoE load vs switch budget before deploying.

Network Cabling

Domain 2

Twisted Pair Cable Categories

Cat	Max Speed	Max Distance	Standard	Notes
Cat 5	100 Mbps	100m	100BASE-TX	Obsolete. Do not install.
Cat 5e	1 Gbps	100m	1000BASE-T	Most common existing install. Minimum acceptable new install.
Cat 6	1 Gbps (100m) / 10 Gbps (55m)	100m	10GBASE-T	Common new install. 10G limited to 55m.
Cat 6a	10 Gbps	100m	10GBASE-T	Augmented Cat 6. Full 10G at 100m. Thicker, stiffer cable.
Cat 7	10 Gbps	100m	10GBASE-T	Individually shielded pairs + overall shield. Data center use.
Cat 8	25–40 Gbps	30m	25/40GBASE-T	Data center only. Short runs between ToR switches and servers.

UTPUnshielded Twisted Pair. Most common. No shielding. Susceptible to EMI. Used in offices. STPShielded Twisted Pair. Overall foil or braid shield. Used near interference sources (motors, fluorescent lights). F/UTPFoiled/Unshielded — overall foil shield, unshielded pairs. S/FTPBraided shield overall + foiled individual pairs. Maximum shielding. Used in Cat 7 and Cat 8.

RJ-45 Wiring Standards

T568A (Pin Order)

Pin 1: Green/White
Pin 2: Green
Pin 3: Orange/White
Pin 4: Blue
Pin 5: Blue/White
Pin 6: Orange
Pin 7: Brown/White
Pin 8: Brown

T568B (Pin Order) — US Standard

Pin 1: Orange/White
Pin 2: Orange
Pin 3: Green/White
Pin 4: Blue
Pin 5: Blue/White
Pin 6: Green
Pin 7: Brown/White
Pin 8: Brown

Straight-ThroughSame standard (T568B/T568B or T568A/T568A) on both ends. Connects different device types: PC to switch, switch to router. CrossoverT568A on one end, T568B on the other. Connects same device types directly: PC to PC, switch to switch. Modern devices use Auto-MDIX and don't require crossover cables. RJ-116-pin (6P2C or 6P4C). Used for telephone lines, DSL modems. Smaller than RJ-45. Not interchangeable with RJ-45.

T568B is the US standard and the most common. Memorize the pin order: Orange/White, Orange, Green/White, Blue, Blue/White, Green, Brown/White, Brown. The exam will test which color goes on which pin.

Cable Tools

CrimperAttaches RJ-45 (or RJ-11) connector to cable. Cuts, strips, and crimps in one motion. Requires correct connector for cable gauge. Punchdown ToolTerminates individual conductors into IDC (Insulation Displacement Connector) slots on patch panels and keystone jacks. 110-type and Krone are common blade styles. Cable TesterVerifies continuity and correct pin mapping on completed cable. Catches wiring errors, opens, and shorts. Basic testers check continuity; advanced testers measure signal characteristics. Toner ProbeTwo-part tool: tone generator clips to one end, probe traces the cable through walls, bundles, and ceilings by detecting the tone. Used to find and label unknown cable runs. Loopback PlugConnects TX to RX pins. Tests NIC/transceiver functionality in isolation. Confirms port can send and receive without needing a switch or cable run. Cable StripperRemoves outer jacket without nicking conductors. Use before crimping or punchdown. Correct depth setting is critical. Network TAPIntercepts network traffic for monitoring/analysis. Passive TAP copies traffic without affecting it. Active TAP may introduce slight delay. Used for packet capture and IDS deployment.

Fiber Optic Cable

Single-Mode Fiber (SMF)

Core: 9 µm. One light path. Laser source.
Long distance: up to 40km+ for some standards.
Jacket color: Yellow.
Used for inter-building, campus, WAN links.
More expensive transceivers.

Multi-Mode Fiber (MMF)

Core: 50 or 62.5 µm. Multiple light paths.
Short distance: up to ~550m (OM4) at 10G.
Jacket: Orange (OM1/OM2), Aqua (OM3/OM4), Lime (OM5).
Used intra-building, data center, short runs.
Less expensive transceivers (LED/VCSEL).

Fiber Connectors

LC (Lucent/Local Connector)Small form-factor. RJ-45-style latch. Most common in modern enterprise and data center. Used with SFP/SFP+ transceivers. SC (Subscriber Connector)Square. Push-pull mechanism. Older standard. Still common in some deployments. ST (Straight Tip)Round. Bayonet twist-lock. Older standard. Used in legacy installations and some military/government networks. MT-RJDuplex connector in a small footprint. Both fibers in one connector. Less common.

Coaxial Cable

StructureInner conductor → dielectric insulator → braided shield → outer jacket. The shield provides EMI protection and ground reference. F-Type ConnectorThreaded connector used for CATV (cable TV) and cable modem connections. Screw-on connection. The center conductor of the coax acts as the pin. BNC ConnectorBayonet Neill-Concelman. Twist-lock coax connector. Used in older 10BASE-2 Ethernet (Thinnet), CCTV, and test equipment. RG-6Modern coax standard for CATV and satellite. Thicker conductor, better shielding than RG-59. Use for cable modem and antenna runs. RG-59Older coax. Thinner. Used for short CCTV runs. Higher signal loss over distance than RG-6.

Copper Cable Problems

AttenuationSignal weakens over distance. Why there are maximum cable length limits. Exceeding limits = data errors, dropped connections. CrosstalkSignal from one wire pair interferes with adjacent pair. NEXT = Near-End Crosstalk (at transmitting end). FEXT = Far-End Crosstalk (at receiving end). Twisting the pairs reduces crosstalk. EMIElectromagnetic Interference from external sources (motors, fluorescent lights, microwave ovens). STP or conduit mitigates EMI. OpenBroken conductor — no continuity. Shows as open on cable tester. Cause: sharp bend, crushing, bad crimp, cut wire. ShortTwo conductors touching that shouldn't be. Can be partial (resistive short) or full. Cause: bad crimp, over-stripped insulation. Impedance MismatchCable impedance doesn't match device. Common with coax. Causes signal reflections and data errors.

IP Addressing & Network Configuration

Domain 2

Internet Connection Types

DSLDigital Subscriber Line. Uses existing phone lines. ADSL = asymmetric (faster download than upload). VDSL = faster. Max speed limited by distance from provider's CO (Central Office). CableUses CATV coax infrastructure. F-type connector. DOCSIS standard. Faster than DSL. Shared bandwidth with neighbors (slows during peak hours). Fiber (FTTH/FTTP)Fiber to the Home/Premises. Fastest consumer option. Symmetrical speeds (same upload and download). ONT (Optical Network Terminal) converts fiber to Ethernet at premises. Fixed WirelessPoint-to-point or point-to-multipoint radio link. Requires line of sight. Used in rural areas without cable/fiber infrastructure. Cellular (4G LTE / 5G)Mobile data. 4G LTE: 10–50 Mbps typical. 5G Sub-6: 100–300 Mbps. 5G mmWave: 1+ Gbps (short range). Used as primary or failover connection. SatelliteAvailable anywhere with sky view. High latency (600ms+ geostationary, ~20-40ms Starlink LEO). Starlink dramatically improved satellite viability. Weather-sensitive.

IPv4 Addressing

Format32-bit address. Written in dotted-decimal: four octets 0–255. Example: 192.168.1.100 Subnet MaskDefines network vs host portion. 255.255.255.0 = /24 = last octet is host. 255.255.0.0 = /16 = last two octets are host. Private Ranges10.0.0.0/8 (Class A), 172.16.0.0–172.31.255.255/12 (Class B), 192.168.0.0/16 (Class C). Not routable on internet. Require NAT to reach public internet. Loopback127.0.0.1. Always refers to the local machine. Used to test TCP/IP stack without network hardware. APIPA169.254.x.x / 169.254.0.0/16. Automatically assigned when DHCP fails. Device can only reach other APIPA addresses on same segment. Symptom of DHCP issue. BroadcastLast address in a subnet. Example: 192.168.1.255 in a /24. Sent to all hosts in subnet. Routers do not forward broadcasts. Default GatewayRouter's IP on the local subnet. Traffic destined outside local subnet is sent here. Wrong or missing gateway = no internet, but local LAN still works.

Classful addressing for the exam: Class A = 1–126.x.x.x (/8). Class B = 128–191.x.x.x (/16). Class C = 192–223.x.x.x (/24). Class D = 224–239 (multicast). Class E = 240–255 (reserved/experimental). 127.x.x.x = loopback (not Class A routable).

IPv6 Addressing

Format128-bit. Written as 8 groups of 4 hex digits separated by colons. Example: 2001:0db8:85a3:0000:0000:8a2e:0370:7334 Shortening Rules1) Remove leading zeros within groups: 0042 → 42. 2) Replace one consecutive group of all-zero hextets with :: (only once per address). Example: 2001:db8::1 Loopback::1 (equivalent of IPv4 127.0.0.1) Link-LocalFE80::/10. Auto-configured on every IPv6 interface. Scope limited to local link — not routed. Equivalent of IPv4 APIPA but always present, not a fault indicator. Global Unicast2000::/3. Publicly routable IPv6 addresses. Equivalent of public IPv4. No BroadcastIPv6 uses multicast instead of broadcast. All-nodes multicast: FF02::1. All-routers multicast: FF02::2.

TCP vs UDP

Feature	TCP	UDP
Connection	Connection-oriented (3-way handshake: SYN → SYN-ACK → ACK)	Connectionless. Send and forget.
Reliability	Guaranteed delivery. Retransmits lost packets.	No guarantee. Packets may arrive out of order or not at all.
Speed	Slower (overhead from acknowledgments)	Faster (no handshake, no ACKs)
Order	Sequenced — reassembled in correct order	Unsequenced — application must handle
Use Cases	HTTP/S, FTP, SSH, SMTP, email — anything where accuracy matters	DNS, DHCP, VoIP, video streaming, gaming — speed over accuracy

Well-Known Ports

20/21TCPFile Transfer ProtocolFTP

22TCPSecure Shell / SFTPSSH

23TCPTelnet (insecure)Telnet

25TCPSimple Mail Transfer ProtocolSMTP

53TCP/UDPDomain Name ServiceDNS

67/68UDPDynamic Host Config ProtocolDHCP

80TCPHypertext Transfer ProtocolHTTP

110TCPPost Office Protocol v3POP3

123UDPNetwork Time ProtocolNTP

137–139TCP/UDPNetBIOS (legacy Windows)NetBIOS

143TCPInternet Message Access ProtocolIMAP

161/162UDPNetwork Mgmt Protocol (trap)SNMP

389TCPLightweight Directory AccessLDAP

443TCPHTTP Secure (HTTP over TLS)HTTPS

445TCPSMB / Windows File SharingSMB

514UDPSyslog (centralized logging)Syslog

587TCPSMTP (submission, authenticated)SMTP Alt

993TCPIMAP over SSL/TLSIMAPS

995TCPPOP3 over SSL/TLSPOP3S

3389TCPRemote Desktop ProtocolRDP

Ports 0–1023 = Well-Known (reserved for system services). Ports 1024–49151 = Registered (assigned by IANA for apps). Ports 49152–65535 = Dynamic/Ephemeral (used by clients for outbound connections). The exam primarily tests the well-known ports above.

Network Configuration Concepts

DHCPAutomatically assigns IP, subnet mask, default gateway, and DNS server. DORA process: Discover → Offer → Request → Acknowledge. Lease-based — IP returned to pool when lease expires. DNSResolves domain names to IP addresses. Hierarchical: Root → TLD (.com/.org) → Authoritative server. Local cache checked first, then recursive resolver. DNS Record TypesA = IPv4 address. AAAA = IPv6 address. CNAME = alias to another name. MX = mail server for domain. PTR = reverse lookup (IP to name). SOA = start of authority (zone info). NS = name server for domain. TXT = text records (SPF, DKIM, domain verification). VLANVirtual LAN. Logically segments a switch into separate broadcast domains. Traffic between VLANs requires routing (Layer 3). Improves security and performance. Configured on managed switches. VPNVirtual Private Network. Encrypted tunnel over the internet. Makes remote users appear as if on the local LAN. Protocols: OpenVPN, WireGuard, IPsec, L2TP/IPsec, SSL/TLS VPN. NATNetwork Address Translation. Translates private IP addresses to public IP address for internet access. PAT (Port Address Translation) / overload NAT allows many private IPs to share one public IP using port numbers to track connections.

Network Services & Troubleshooting

Domain 2 / Domain 5

Server Types & Ports

Server Type	Function	Ports
File/Print	Shares files and printers on network	445 (SMB), 139 (NetBIOS)
Web	Hosts websites and web applications	80 (HTTP), 443 (HTTPS)
Mail (Send)	Sends email between domains	25 (SMTP), 587 (submission)
Mail (POP3)	Downloads mail to client (removes from server)	110 (plain), 995 (TLS)
Mail (IMAP)	Syncs mail across devices (stays on server)	143 (plain), 993 (TLS)
DNS	Resolves domain names to IP addresses	53 (TCP/UDP)
DHCP	Assigns IP configuration automatically	67 (server), 68 (client) UDP
LDAP / AD	Directory services, authentication	389 (plain), 636 (TLS)
Syslog	Centralized log collection	514 UDP
NTP	Time synchronization	123 UDP
SNMP	Network device monitoring	161 (queries), 162 (traps) UDP

Network Appliances & Special Systems

Proxy ServerInspects HTTP/S requests. Blocks inappropriate sites. Caches content to reduce bandwidth. Logs user browsing. Hides internal IP addresses from internet. UTMUnified Threat Management. Single appliance combining: firewall, IDS/IPS, antivirus, spam filtering, VPN, content filtering. Common in SMB environments. IDSIntrusion Detection System. Monitors traffic and alerts on suspicious activity. Passive — detects but does NOT block. IPSIntrusion Prevention System. Inline device that actively blocks suspicious traffic. Can cause false positives that disrupt legitimate traffic. SCADA/ICSSupervisory Control and Data Acquisition / Industrial Control Systems. Controls industrial equipment (power plants, water treatment, manufacturing). Critical infrastructure — high security risk if networked. Legacy systems often lack modern security. IoT DevicesInternet of Things. Smart devices on the network (cameras, thermostats, speakers, locks). Often have weak default security. Isolate on separate VLAN. Change default passwords. Keep firmware updated. Legacy/EOL SystemsEnd-of-Life hardware or software — no longer receives vendor patches or support. Security risk. Isolate from main network. Plan migration. Cannot be left internet-facing.

Network Troubleshooting

Wired Connectivity

Check patch cord at both ends. Try a known-good cable first.
Verify link lights on NIC and switch port — both should be solid or blinking green.
Use loopback plug to test NIC in isolation. Use cable tester to verify cable.
Check speed and duplex settings — auto/auto mismatch can cause poor performance.
Check for port flapping (link cycling up and down) — indicates bad cable or NIC.

Wireless Issues

Verify Wi-Fi is enabled (not airplane mode).
Check signal strength — move closer to WAP or add another access point.
Check for channel overlap/interference — use Wi-Fi analyzer to find best channel.
2.4 GHz = longer range, more interference. 5 GHz = shorter range, faster, less congestion.
Check SSID and security key are correct. Forget network and reconnect if authentication fails.

VoIP Issues

Latency — one-way delay in ms. Should be <150ms for acceptable voice quality.
Jitter — variation in packet delay. Should be <30ms. Causes choppy/robotic audio.
Packet Loss — missing packets. Even 1% loss degrades voice quality noticeably.
QoS (Quality of Service) — prioritizes VoIP traffic over less time-sensitive traffic on the network. Configure on managed switches and routers.

Virtualization & Cloud Computing

Domain 4

Hypervisor Types

Type 1 — Bare MetalRuns directly on hardware. No host OS layer. Best performance and resource efficiency. Enterprise standard. Examples: VMware ESXi, Microsoft Hyper-V (server role), Proxmox, Xen, KVM. Type 2 — HostedRuns as an application on top of a host OS. Host OS must run first. Easier to set up. Slightly lower performance. Examples: VMware Workstation, Oracle VirtualBox, Parallels (macOS).

Type 1 = enterprise/server (bare metal, most efficient). Type 2 = desktop/developer (hosted on OS, easy to use). The exam will describe a scenario and ask which type. If it mentions running on a server with no other OS, it's Type 1. If it mentions running inside Windows or macOS, it's Type 2.

Uses for Virtualization

Sandboxing — test software or malware in an isolated environment without risk to the host.
Legacy support — run old OS/software that won't run on modern hardware or current OS.
Cross-platform testing — run Linux, Windows, and macOS on the same physical machine.
Training / lab environments — spin up and destroy environments without affecting production.
Server consolidation — replace many underutilized physical servers with VMs on fewer hosts. Reduces hardware, power, and cooling costs.
Container virtualization — lightweight OS-level virtualization sharing the host kernel. Docker is the standard. Much faster startup than full VMs. Less isolation.
Application virtualization — run apps in isolated containers without full OS. Example: Citrix XenApp.

Cloud Deployment & Service Models

Deployment Models

PublicMulti-tenant. CSP owns and manages. AWS, Azure, GCP. Cheapest, least control. PrivateSingle-organization. On-prem or hosted. Most control, highest cost. CommunityShared by orgs with common needs (government, healthcare). Split cost and control. HybridMix of above. Sensitive data on-prem, scalable workloads in public cloud.

Service Models

IaaSYou manage OS and up. Provider manages hardware. Target: sysadmins. Example: EC2, Azure VMs. PaaSYou manage app and data. Provider manages OS+. Target: developers. Example: App Engine. SaaSProvider manages everything. You just use it. Target: end users. Example: Office 365, Gmail.

Remember the target audience: IaaS → sysadmins. PaaS → developers/DBAs. SaaS → end users. The more you manage, the more control and responsibility you have. The more the provider manages, the less control but also less overhead.

Mobile Devices

Domain 1

Laptop Components

RAM (SO-DIMM)Laptop uses SO-DIMM (half the length of desktop DIMM). DDR4 or DDR5 typically. Some ultrabooks have RAM soldered to motherboard — not upgradeable. StorageM.2 NVMe SSD (fastest), M.2 SATA SSD, or 2.5" SATA SSD. Ultrabooks often use soldered NVMe — check specs before purchase if upgradeability matters. BatteryRechargeable lithium-ion or lithium-polymer. Internal (ultrabooks) or removable (older laptops). Capacity measured in mAh or Wh. Swollen battery = discontinue use immediately (fire/explosion risk). DisplayLCD or OLED panel. Connected to motherboard via eDP (embedded DisplayPort) ribbon cable. Backlight (CCFL legacy or LED). Inverter required for CCFL backlights (legacy). Wireless NICM.2 Key E or mini PCIe card. Supports Wi-Fi and often Bluetooth on same card. Antenna wires run through display lid. TouchpadBuilt-in pointing device. Connected via internal USB or PS/2. Some have integrated left/right buttons; others use entire surface as button (clickpad). Webcam / MicBuilt into display bezel. Connected via internal USB. Can be physically covered with shutter on privacy-conscious designs. BiometricsFingerprint reader (in touchpad or power button) or IR camera (Windows Hello facial recognition). Hello = PIN, fingerprint, facial recognition, or security key. NFCNear Field Communication. ~4cm range. Used for contactless payments, pairing peripherals, device tap-to-connect. DigitizerTouchscreen layer over display. Capacitive (finger touch) or active pen (pressure-sensitive stylus with digitizer beneath). Used in convertible laptops and tablets.

Mobile Device Connectivity

Wi-Fi (802.11)Wireless LAN. 802.11a/b/g = legacy. 802.11n (Wi-Fi 4) = 600 Mbps, 2.4/5 GHz. 802.11ac (Wi-Fi 5) = 3.5 Gbps, 5 GHz. 802.11ax (Wi-Fi 6/6E) = 9.6 Gbps, 2.4/5/6 GHz. BluetoothShort-range (~10m). Used for peripherals (headphones, keyboards, mice), file transfer, car audio. Pairing: devices exchange keys during initial connection. BT 5.0+ = 40m range, faster transfers. CellularRequires SIM or eSIM. 4G LTE = 10–150 Mbps. 5G Sub-6 = 100–300 Mbps. 5G mmWave = 1+ Gbps (dense urban only). Hotspot shares cellular data over Wi-Fi. GPSGlobal Positioning System. Passive — receives signals from satellites, doesn't transmit. Used for navigation and location services. Assisted GPS (A-GPS) uses cellular/Wi-Fi for faster fix. NFC~4cm range. Contactless payments (Apple Pay, Google Pay), badge access, quick device pairing (NFC-initiated Bluetooth connection). Airplane ModeDisables ALL wireless radios (cellular, Wi-Fi, Bluetooth, NFC). Wi-Fi and Bluetooth can be re-enabled individually while in airplane mode on most devices. IR (Infrared)Requires line-of-sight. Short range. Used as TV remote replacement on some phones. Not common in modern devices.

Mobile Troubleshooting

Swollen BatteryStop using immediately. Lithium swelling indicates chemical breakdown. Risk of fire/rupture. Do not puncture or charge. Take to certified recycler/repair shop. OverheatingCheck for background apps consuming CPU. Remove case if charging (reduces heat dissipation). Avoid charging in direct sunlight. Throttling = device slowing itself to reduce heat. Screen IssuesDim display = failed backlight or low brightness setting. Ghost touch = digitizer calibration or damage. Dead pixels = permanent display defect. Flickering = loose display cable or failing display. Poor Battery LifeCheck screen brightness (biggest drain), background app refresh, location services, push email. Battery health degrades over charge cycles — below 80% health = consider replacement. Connectivity IssuesToggle airplane mode on/off to reset all radios. Forget and reconnect to Wi-Fi. Check cellular signal strength. Reset network settings if persistent (erases saved Wi-Fi passwords). Malware IndicatorsUnexpected data usage, excessive battery drain, unauthorized camera/mic access, unexpected pop-ups, new unknown apps, slow performance. Factory reset as last resort. Improper ChargingUse correct wattage charger — too low charges slowly, too high can damage battery. Heat during charging = normal in moderation, but extreme heat indicates fault. Check cable and port for damage/debris.

Laptop Disassembly Best Practices

Document every step — photograph before and during disassembly.
Use proper tools: spudger/pry tool, Phillips and Torx screwdrivers, tweezers.
Keep screws organized — use a magnetic mat or tape screws to labeled paper.
Disconnect battery before working on any internal components.
Use ESD wrist strap — laptops are more ESD-sensitive than desktops due to compact design.
Reference manufacturer documentation or iFixit guides for model-specific disassembly.
Ribbon cables and ZIF connectors require care — lift the locking tab before pulling cable.

Printers & Multifunction Devices

Domain 3

Printer Types

Type	Technology	Speed	Quality	Key Use Case
Laser	Toner (dry powder) fused with heat	Fast	High	Office documents. High volume. Low cost per page.
Inkjet	Liquid ink sprayed through nozzles	Medium	Excellent color	Photo printing, home use, low volume color.
Thermal	Heat on thermochromic paper	Fast	Low res	Receipts, labels, shipping. No ink/toner needed.
Impact / Dot Matrix	Pins strike inked ribbon onto paper	Slow	Low	Multi-part carbon forms. Loud. Noisy environments.
3D Printer	FDM (filament) or SLA (resin)	Slow	3D objects	Prototyping, custom parts, models.

Laser Printing Process — 7 Steps

Processing — Print job sent to printer. Data converted to raster image by RIP (Raster Image Processor).

Charging — Primary corona wire or charge roller applies a uniform high-voltage negative charge to the entire drum surface.

Exposing (Writing) — Laser beam selectively removes negative charge from drum where toner should adhere, creating a latent image.

Developing — Negatively charged toner particles attracted to the less-negative (exposed) areas of the drum. Toner sticks to latent image.

Transferring — Transfer corona wire or roller applies a positive charge to the paper, pulling negatively charged toner off the drum onto the paper.

Fusing — Fuser assembly (heat roller + pressure roller) melts toner into the paper fibers using heat (~400°F) and pressure. Permanently bonds toner.

Cleaning — Cleaning blade scrapes remaining toner off drum. Erase lamp (or charge roller) removes residual charge, preparing drum for next page.

The 7 steps in order: Processing → Charging → Exposing → Developing → Transferring → Fusing → Cleaning. A memory trick: PCEDT FC or "Pretty Cool Elephants Don't Typically Fight Cats." This is one of the most tested topics on Core 1.

Printer Troubleshooting

Symptom	Likely Cause	Fix
Blank pages	Empty toner/ink, print head issue, protective strip not removed from new toner	Replace consumable, shake toner, remove protective tape
Vertical lines or streaks	Dirty or scratched drum, low toner, dirty corona wire	Clean drum/corona wire, replace toner or drum
Smudged output (laser)	Fuser not reaching temperature, fuser worn out	Replace fuser assembly
Smudged output (inkjet)	Clogged print head, wrong paper type	Run print head cleaning utility, use correct paper
Ghost images (faded repeat)	Drum not cleaned fully, fuser problem	Replace drum unit or fuser
Paper jams	Worn pickup rollers, wrong paper, paper not properly loaded, debris in paper path	Clean/replace rollers, use correct paper, clear debris
Wrinkled pages	Worn exit rollers, damp paper	Replace exit rollers, use fresh paper stored correctly
Garbled/incorrect output	Wrong or corrupt driver, PDL mismatch (PostScript vs PCL)	Reinstall correct driver, verify PDL settings
Color misregistration	Color planes misaligned	Run calibration utility
Grinding noise	Worn gears, debris in paper path	Clean paper path, replace gear assembly if worn

Printer Maintenance by Type

Laser — TonerReplace when output fades. Shake cartridge gently to redistribute toner before replacing for a few more pages. Remove protective film strip from new cartridges. Laser — Maintenance KitIncludes fuser, transfer roller, and pickup rollers. Replace at manufacturer-specified page count (typically 200,000–300,000 pages). Reset page count after replacement. Laser — DrumSeparate from toner in some designs. Replace when output quality degrades despite fresh toner. Protect from light — photosensitive. Inkjet — CartridgesReplace when ink low. Use OEM or compatible cartridges. Some printers require all colors even for B&W. Inkjet — Print HeadRun cleaning cycle from printer software. Multiple cleans may be needed. Excessive cleaning wastes ink. Allow head to dry if clogged — sometimes resolves overnight. Thermal — Heating ElementClean with isopropyl alcohol and cotton swab. Replace paper rolls — thermal paper has a limited shelf life and is heat/light sensitive. Impact — RibbonReplace ink ribbon when output fades. Replace print head if pins are worn or broken.

Printer Connectivity & Sharing

USB — most common local connection. Direct from PC to printer.
Ethernet — network printing. Printer gets IP address. All LAN users can print. Preferred for offices.
Wi-Fi — wireless network printing. Same as Ethernet for users but wireless. Wi-Fi Direct allows direct connection without a WAP.
Bluetooth — short-range. Mobile printing from phone/tablet. Limited range and speed.
Cloud Printing — Google Cloud Print (deprecated), HP ePrint, AirPrint (Apple), Mopria (Android). Print from anywhere via internet.
Printer Sharing — connect printer to one Windows PC, share it. Other users connect via \\computername\printername. Host PC must be on for print jobs to process.

Security Fundamentals

Domain 2 / Domain 3

CIA Triad

ConfidentialityOnly authorized users can access data. Enforced by: encryption, access controls, authentication, classification. Breach = data disclosed to unauthorized party. IntegrityData has not been tampered with or altered. Enforced by: hashing, digital signatures, checksums, access controls. Breach = unauthorized modification of data. AvailabilitySystems and data accessible when needed by authorized users. Enforced by: redundancy, backups, RAID, failover, UPS. Breach = system or data inaccessible (ransomware, DDoS, hardware failure).

CIA Triad = the mission. Confidentiality = need-to-know. Integrity = you can trust the intel is accurate. Availability = comms are up when you need them. Lose any leg and the mission is compromised.

Identity and Access Management

IdentificationWho you claim to be. Username, employee ID, email address. Not yet verified. AuthenticationProving your claimed identity. Password, PIN, biometric, smart card, security token. AuthorizationWhat you are allowed to access after authentication. Determined by permissions, group membership, ACLs. Accounting/AuditingTracking what authenticated users did. Logs of access, changes, and actions. Non-repudiation — user cannot deny actions.

Security Principles

Least PrivilegeUsers and processes receive only the minimum permissions required for their job function. Nothing more. Limits damage from compromised accounts or insider threats. Implicit DenyDefault deny unless explicitly permitted. Firewalls and ACLs deny all traffic not explicitly allowed. Safer than explicit deny (must list everything you want to block). Zero TrustNever trust, always verify. Every access request authenticated and authorized regardless of network location. Assumes breach — even internal traffic is treated as untrusted. Defense in DepthMultiple layers of security. No single control is relied upon. Physical → Network → Host → Application → Data layers. Each layer slows or stops an attacker who bypasses another. Separation of DutiesNo single person can complete a sensitive process alone. Requires two or more people. Prevents fraud and insider threats in critical processes. Need to KnowAccess granted only to information required for the specific role. Even users with the same clearance level cannot access each other's data if they don't need it.

Authentication Methods

MFA FactorsSomething you know (password, PIN, security question). Something you have (smart card, hardware token, phone/authenticator app). Something you are (fingerprint, retina, facial recognition, voice). True MFA requires two DIFFERENT factor types. Windows HelloMicrosoft's biometric and PIN authentication framework. Options: PIN, fingerprint, facial recognition (IR camera), FIDO2 security key. PIN is device-specific — not same risk as password. SSOSingle Sign-On. Authenticate once, access multiple systems. SAML is common protocol. Active Directory provides SSO for Windows domain. Reduces password fatigue but single point of failure if compromised. OTPOne-Time Password. Valid for one use only. TOTP = Time-based (Google Authenticator, expires in 30s). HOTP = Counter-based. Prevents replay attacks. Hard TokenPhysical security key (YubiKey, RSA SecurID). Generates OTP or uses FIDO2 protocol. Phishing-resistant — code tied to specific website URL. Soft TokenAuthenticator app on smartphone (Google Authenticator, Microsoft Authenticator, Duo). Generates TOTP codes. Less secure than hard token (phone can be compromised) but more secure than SMS.

Password + PIN = NOT MFA (both "something you know"). Password + authenticator app = MFA ("know" + "have"). Fingerprint + facial recognition = NOT MFA (both "something you are"). Two factors must come from two DIFFERENT categories.

NTFS vs Share Permissions

NTFS PermissionsApply locally (direct access) AND over network. Granular: Full Control, Modify, Read & Execute, List Folder Contents, Read, Write. Inherited from parent folder by default. Most restrictive wins when multiple permissions conflict. Share PermissionsApply ONLY when accessing over the network (not locally). Simple: Full Control, Change, Read. Easier to manage but less granular. Effective PermissionsWhen BOTH NTFS and Share permissions apply (network access), the MOST RESTRICTIVE of the two combinations wins. Example: NTFS = Full Control, Share = Read → Effective = Read over network. InheritanceNTFS permissions flow down from parent folder to subfolders and files. Can break inheritance on specific folders to set unique permissions. Explicit permissions override inherited.

Local access = only NTFS permissions apply. Network access = both NTFS and Share permissions apply, most restrictive combination wins. The exam loves this distinction — read the scenario carefully to determine if the user is accessing locally or over the network.

Encryption Concepts

HashingOne-way function. Input → fixed-length digest. Cannot reverse. Used to verify integrity (MD5, SHA-256). Same input always produces same hash. Different input = completely different hash (avalanche effect). Symmetric EncryptionSame key encrypts and decrypts. Fast. Key distribution is the challenge — how do you securely share the key? AES, 3DES. Used for bulk data encryption. Asymmetric EncryptionPublic/private key pair. Public key encrypts (anyone can encrypt). Private key decrypts (only owner can decrypt). Solves key distribution problem. Slow. RSA, ECC. Used for key exchange and authentication. Digital SignatureSender hashes message, encrypts hash with their PRIVATE key. Receiver decrypts with sender's PUBLIC key, re-hashes and compares. Proves identity (authentication) and message integrity. TPMTrusted Platform Module. Hardware chip (or firmware fTPM) that securely stores cryptographic keys. Used by BitLocker for full-disk encryption. Keys never leave TPM in plaintext. Required for Windows 11. HSMHardware Security Module. Removable/external dedicated device for cryptographic key storage and operations. Used in enterprise PKI and payment systems. More portable than onboard TPM. BitLockerWindows full-disk encryption. Requires TPM or USB startup key. Encrypts entire volume. Protects data if drive is removed. Recovery key should be backed up to AD or Microsoft account.