comptia a+ core 1

Laptop Hardware

Laptop components are compact and often model-specific.

Laptop batteries, storage, keyboards, cameras, microphones, and wireless cards have different replacement procedures.

Follow manufacturer instructions, disconnect power, and use ESD precautions before service.

Why must a replacement laptop battery match the exact model/specifications? → Fit, connector, electrical characteristics, and safe operation vary.

What is a benefit of replacing an HDD with an SSD? → Faster access, greater shock resistance, and lower mechanical failure risk.

What should you do before replacing internal laptop hardware? → Shut down, disconnect power, consult service instructions, and use suitable ESD precautions.

A laptop webcam is missing after an OS update; what should you examine? → Privacy settings, device detection, drivers, and hardware function.

Why are SO-DIMMs common in laptops? → They are physically smaller memory modules suited to compact devices.

Connecting Mobile Devices

USB-C is connector shape and does not guarantee a specific protocol or speed.

Bluetooth supports short-range peripherals.

Wi-Fi hotspots and tethering share a cellular Internet connection.

NFC supports very-close-range communication.

Does a USB-C connector always mean Thunderbolt support? → No; connector form factor alone does not establish supported protocols.

What does tethering mean? → Sharing one device's network connection with another device.

When might you use a mobile hotspot? → To share a phone's cellular Internet connection over Wi-Fi.

What is NFC commonly used for? → Tap payments, close-range access credentials, or pairing assistance.

What is the difference between Bluetooth and USB for connecting peripherals? → Bluetooth is wireless; USB is a wired connection that may also provide power.

Mobile Device Accessories

Docking stations expand a device's ports and sometimes charging and displays.

Stylus and digitizer input enable precision and pressure sensitivity when supported.

Headsets, speakers, webcams, trackpads, and drawing tablets serve different inputs/outputs.

What does a docking station do? → Expands connections such as displays, USB, Ethernet, and often power via a single laptop connection.

What is a port replicator? → A device that exposes additional or more accessible external ports.

What makes an active stylus different from a basic capacitive stylus? → It may support pressure sensitivity, palm rejection, and enhanced precision.

What is a trackpad? → A touch-sensitive surface controlling a pointer.

A designer wants pressure-sensitive drawing input; what accessory is appropriate? → A compatible active stylus and digitizer/drawing tablet.

Mobile Device Networks

3G, 4G LTE, and 5G are cellular generations.

GPS receives positioning signals from satellites.

SIM/eSIM identifies a subscriber for cellular service.

Wi-Fi and Bluetooth use local radio technologies.

What does a SIM or eSIM identify? → Subscriber credentials used to authenticate on a cellular network.

Does GPS require cellular data to determine geographic location? → No; satellite positioning can work without active cellular data.

What is the difference between Wi-Fi and cellular connectivity? → Wi-Fi connects to a nearby wireless network; cellular connects through a carrier's radio network.

Why might a phone show signal but have no Internet access? → Possible cellular data restrictions, service issues, roaming limitations, or network configuration faults.

What does LTE stand for? → Long-Term Evolution, associated with 4G mobile networks.

Mobile Device Management

MDM enforces device policies and manages enrolled devices.

BYOD means employee-owned devices.

COPE means company-owned but personally enabled.

Enterprise sync, remote wipe, app controls and compliance policies require careful privacy choices.

What does MDM stand for? → Mobile Device Management.

What does BYOD stand for? → Bring Your Own Device: employees use personally owned devices for work.

What does COPE stand for? → Corporate-Owned, Personally Enabled.

Why would an organization use MDM? → To manage policies, configuration, apps, device compliance, and remote actions.

What is a risk of remote wipe on BYOD? → Potentially affecting personal information unless work/personal data are appropriately separated.

Introduction to IP

IP addresses identify network endpoints.

TCP provides reliable ordered delivery with SYN/SYN-ACK/ACK setup.

UDP is connectionless and has no built-in ordered delivery guarantees.

Source and destination ports distinguish application endpoints.

Encapsulation wraps data in successive networking headers.

Is TCP port 443 a physical computer connector? → No; it is a logical transport-layer endpoint number.

What are the TCP handshake steps? → SYN, SYN-ACK, ACK.

What does UDP lack compared with TCP? → Built-in reliable ordering, acknowledgments, and retransmission.

If a client sends 10.0.0.1:53000 to 10.0.0.2:443, what is the reply direction? → 10.0.0.2:443 to 10.0.0.1:53000.

What is an ephemeral port? → A temporary local port commonly used for client communication.

What is encapsulation? → The process of adding networking headers/trailers as data is prepared for transmission.

Common Ports

Recognize port-to-service associations and what the application actually does.

DNS resolves names, DHCP leases configuration, SSH enables encrypted remote shell, SMB shares files.

Email protocols SMTP sends, POP3 retrieves, IMAP synchronizes.

Which TCP ports are associated with traditional FTP? → 21 control; 20 active-mode data.

What port does SSH use? → TCP 22.

What port does Telnet use? → TCP 23.

What port is SMTP commonly associated with for mail relay? → TCP 25.

What port is DNS? → TCP/UDP 53.

What ports are DHCP? → UDP 67 server and 68 client.

What ports are HTTP and HTTPS traditionally? → TCP 80 and TCP 443 respectively; HTTP/3 may use UDP 443.

What ports are POP3 and IMAP? → TCP 110 and TCP 143 respectively.

What ports are LDAP and LDAPS? → LDAP TCP/UDP 389; LDAPS typically TCP 636.

What port is SMB? → TCP 445.

What port is RDP? → TCP/UDP 3389.

What ports are NetBIOS services? → Typically UDP 137/138 and TCP 139.

Wireless Network Technologies

802.11 standards differ in bands and capabilities.

2.4 GHz commonly uses nonoverlapping 20 MHz channels 1 6 11 in US.

Channel width affects throughput/interference.

Bluetooth connects peripherals.

RFID tracks tags and NFC enables very-close-range interactions.

What band does 802.11b use? → 2.4 GHz.

Which bands does 802.11n support? → 2.4 and 5 GHz.

What is 802.11ac also called? → Wi-Fi 5, primarily 5 GHz.

What does Wi-Fi 6E add to 802.11ax capability? → Use of the 6 GHz band with compatible hardware.

Which three 2.4 GHz 20 MHz channels are commonly non-overlapping in the US? → 1, 6, and 11.

What does an 80 MHz channel width describe? → The amount of spectrum used, not an 80 MHz center frequency.

Bluetooth, RFID, or NFC for a tap payment? → NFC.

What is channel 6's center frequency? → 2.437 GHz.

Network Services

Recognize server roles including DNS DHCP, file, print, mail, web, Syslog, and authentication.

Security appliances may combine firewall, filtering, and intrusion prevention.

Load balancers distribute requests.

Proxies relay client traffic.

SCADA, IoT, embedded, and legacy devices have special maintenance constraints.

What does a DNS server do? → Resolves names and returns DNS records.

What does a Syslog server do? → Collects and stores system or network log messages.

What is a load balancer? → A service or appliance distributing workload across multiple backend systems.

Why use a proxy server? → To relay and potentially filter/cache client requests.

What is SCADA? → Supervisory Control and Data Acquisition used for monitoring/control of industrial processes.

A shared office printer needs central management; what server role applies? → Print server.

What is an IoT device? → An Internet-connected embedded/special-purpose device.

DNS Configuration

DNS record types answer different questions: A IPv4, AAAA IPv6, CNAME alias, MX mail exchanger, TXT arbitrary verification/policy text.

SPF, DKIM, DMARC support email sender authorization, message signing, and policy.

Separate names from IP assignment.

What does a DNS A record hold? → An IPv4 address for a hostname.

What does an AAAA record hold? → An IPv6 address for a hostname.

What does a CNAME record do? → Creates an alias pointing one DNS name to another DNS name.

Which DNS record identifies a domain's mail servers? → MX.

Which DNS record often stores verification and email-policy text? → TXT.

What is SPF? → Sender Policy Framework: authorizes systems to send mail for a domain.

What is DKIM? → DomainKeys Identified Mail: cryptographic signatures for email authentication.

What is DMARC? → Domain-based Message Authentication, Reporting, and Conformance: policy/reporting built on aligned SPF/DKIM authentication.

A site works by IP but fails by name; what service do you check? → DNS.

DHCP

DHCP provides addresses and network options automatically.

DORA is Discover Offer Request Acknowledge.

Scopes/pools define allocatable IP ranges.

Reservations map a known device to a consistent assignment.

Exhausted pools or unreachable servers cause failures.

What does DHCP stand for? → Dynamic Host Configuration Protocol.

What are the four steps in DHCP DORA? → Discover, Offer, Request, Acknowledge.

What is a DHCP scope? → An address range and related options a DHCP service can distribute.

What is a DHCP reservation? → An IP assignment reserved for a particular client identifier/MAC, generally on a DHCP server.

What does a 169.254.x.x IPv4 address often indicate? → APIPA/link-local addressing, commonly because no DHCP lease was obtained.

What two UDP ports does DHCP use? → 67 server, 68 client.

How is DHCP different from DNS? → DHCP supplies network configuration; DNS resolves names.

VLANs and VPNs

VLANs segment Layer 2 networks/broadcast domains.

Different VLANs require routing to communicate.

VPNs create protected tunnels across other networks.

Client-to-site supports remote users.

Site-to-site joins networks.

What does VLAN stand for? → Virtual Local Area Network.

What is a VLAN used for? → Logically separating switch networks into distinct broadcast domains.

How do devices in separate VLANs communicate? → Through a routing device or Layer 3 switch with appropriate policy.

What does VPN stand for? → Virtual Private Network.

What is a client-to-site VPN? → A remote client establishes a protected connection into an organization's network.

What is a site-to-site VPN? → A protected tunnel connecting two networks.

Does a VLAN alone encrypt traffic? → No; logical segmentation is not encryption.

Network Devices

Routers connect IP networks.

Switches connect devices within LANs.

Wireless APs connect Wi-Fi clients.

Firewalls filter traffic.

Patch panels organize cable runs.

PoE supplies electrical power over Ethernet.

Modems/ONTs terminate access links.

NICs connect devices.

What does a router do? → Forwards packets between different IP networks.

What does a switch primarily do? → Connects devices on a local network and forwards frames based on MAC addresses.

What does a wireless AP do? → Provides wireless LAN connectivity to clients.

What is a patch panel? → Passive cable termination and organization, not a router or switch.

What does PoE stand for? → Power over Ethernet, delivering electrical power with data over supported Ethernet cabling.

What is an ONT? → Optical Network Terminal, commonly the customer-side termination of a fiber provider connection.

What is a NIC? → Network Interface Card/controller connecting a device to a network.

What does a firewall do? → Applies traffic filtering and security policy.

IPv4 and IPv6

IPv4 is 32-bit dotted decimal.

IPv6 is 128-bit hexadecimal groups.

Private IPv4 ranges include 10/8, 172.16/12, 192.168/16.

Public addresses routable on the Internet.

IPv6 link-local commonly fe80::/10.

How many bits in IPv4 and IPv6 addresses? → 32 bits and 128 bits.

Give the three RFC1918 private IPv4 ranges. → 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16.

Is 172.20.10.5 private? → Yes; it lies in 172.16.0.0 through 172.31.255.255.

Is 172.40.1.1 in the RFC1918 private range? → No.

How is IPv6 generally written? → Eight groups of hexadecimal numbers separated by colons, with shorthand compression allowed.

What is an IPv6 link-local prefix? → fe80::/10.

What is the IPv4 loopback address? → 127.0.0.1.

Assigning IP Addresses

Static addresses are configured manually.

Dynamic addresses leased from DHCP.

Subnet mask/prefix identifies network portion.

Default gateway reaches other networks.

DNS server resolves names.

APIPA IPv4 link-local used if automatic DHCP unavailable.

What is a static IP configuration? → Manually assigned IP settings rather than using a dynamic lease.

What is a dynamic IP configuration? → Settings usually received automatically through DHCP.

What does a subnet mask or prefix indicate? → Which address bits identify the local network.

What is a default gateway? → Router used when traffic must leave the local subnet.

What does APIPA mean? → Automatic Private IP Addressing, typically using 169.254.0.0/16 link-local addresses.

A laptop has IP 169.254.25.8 and cannot reach local resources; what is a likely cause? → Failed DHCP lease or DHCP connectivity problem.

Can a machine have valid local networking but incorrect DNS? → Yes; names may fail while direct IP communication still works.

Internet Connection Types

Fiber uses optical light, cable broadband uses coax, DSL uses phone copper, cellular uses provider radio, WISP uses fixed wireless, satellite communicates with orbiting equipment.

Compare latency, coverage, bandwidth, and installation constraints.

Which ISP access technology uses an optical connection? → Fiber.

Which broadband technology commonly uses coaxial cable? → Cable Internet.

What does DSL use? → Existing telephone copper pairs for digital subscriber service.

What is a WISP? → Wireless Internet Service Provider, often providing fixed wireless links.

What access technology may serve very remote areas without wired infrastructure? → Satellite.

Why can geostationary satellite Internet have high latency? → The long radio round-trip distance to geostationary orbit.

What determines whether cellular Internet is viable? → Coverage, signal quality, congestion, plan/service, and equipment.

Network Types

PAN = personal local peripherals.

LAN = local-area network.

WLAN = wireless LAN.

WAN = geographically broad network.

SAN = storage-area network.

Network names indicate scope or purpose, not a specific speed.

What does PAN stand for? → Personal Area Network, such as phone and nearby Bluetooth accessories.

What does LAN stand for? → Local Area Network, covering a home, office, or local site.

What does WLAN stand for? → Wireless Local Area Network.

What does WAN stand for? → Wide Area Network linking sites across geographic distances.

What does SAN stand for? → Storage Area Network used for dedicated storage connectivity.

Is Wi-Fi a WLAN technology or WAN technology? → Usually WLAN technology.

Network Tools

Crimper attaches cable plugs.

Punch-down tool seats conductors in termination blocks.

Cable tester checks continuity/wiring.

Toner and probe trace cables.

Wi-Fi analyzer checks channels/signals.

Loopback plug tests port operation.

Network tap captures mirrored/pass-through traffic for analysis.

What tool attaches an RJ45 modular plug to cable? → Crimper.

What tool seats twisted-pair wires on a 110-type block? → Punch-down tool.

What tool helps identify which cable runs to a wall jack? → Tone generator and probe.

What tool checks wire mapping and continuity? → Cable tester.

What tool surveys channel usage and signal strength? → Wi-Fi analyzer.

What is a loopback plug for? → Testing whether an interface can send and receive through a local test path.

What is a network tap? → A device that makes network traffic available for monitoring/analysis.

If an Ethernet run fails after termination, what tool should you use first? → A cable tester.

Display Types

LCD uses a backlight, with TN IPS VA variations.

OLED pixels emit their own light.

Mini-LED is a backlight technology.

Digitizer turns touch/stylus movement into input.

Legacy fluorescent LCD backlights may use inverters.

What is a key difference between LCD and OLED? → LCD uses a separate backlight; OLED pixels emit their own light.

What is IPS known for? → Strong viewing angles and generally accurate color.

What is TN commonly associated with? → Fast response and often weaker viewing angles/color than IPS.

What is VA often known for? → High contrast relative to typical IPS, with trade-offs.

What is Mini-LED in a monitor? → A backlighting method that uses many small LEDs; it is not the same as OLED.

What does a touchscreen digitizer do? → Detects touch or stylus location and converts it to input.

What might a legacy LCD inverter control? → Power for a fluorescent backlight.

Display Attributes

Resolution counts horizontal by vertical pixels.

Pixel density indicates pixels per unit area.

Refresh rate is screen updates per second in Hz.

Color gamut is range of displayable colors.

Response time differs from refresh rate.

What does 1920x1080 resolution mean? → 1920 pixels horizontally and 1080 vertically.

What does refresh rate measure? → How often the display updates each second, measured in Hz.

What is pixel density? → The concentration of pixels per unit of screen area, often PPI.

What is color gamut? → The range of colors a display can represent.

Is response time the same as refresh rate? → No; response time measures pixel transitions; refresh rate measures display updates.

What display factor helps with detailed high-density text? → Resolution and pixel density.

Network Cables

UTP and STP twisted pair differ in shielding.

Ethernet copper categories differ by rating.

Plenum cable satisfies certain fire/smoke requirements.

Direct-burial cable is designed for underground environment.

EMI affects copper signal quality.

What does UTP stand for? → Unshielded Twisted Pair.

What does STP stand for in cable context? → Shielded Twisted Pair.

Why twist conductors in Ethernet cable? → To reduce electromagnetic interference and crosstalk.

What cable jacket is designed for air-handling plenum spaces? → Plenum-rated cable meeting the applicable code.

Which cable type is designed for burial in ground? → Direct-burial-rated cable.

What is EMI? → Electromagnetic interference that can disrupt electrical signals.

568A and 568B Colors

T568A and T568B are 8P8C twisted-pair termination standards.

Pair sequence matters.

Straight-through cable normally uses the same scheme at both ends.

Different schemes create a traditional crossover arrangement.

What is the pin 1 color in T568A? → White/green.

What is the pin 1 color in T568B? → White/orange.

What is the T568B pin order 1 through 8? → White/orange, orange, white/green, blue, white/blue, green, white/brown, brown.

What is the T568A pin order 1 through 8? → White/green, green, white/orange, blue, white/blue, orange, white/brown, brown.

What is a straight-through twisted pair cable? → The same wiring standard is used on both ends.

How does a traditional crossover cable differ? → One end T568A and the other T568B, swapping transmit/receive pairs for certain legacy connections.

Optical Fiber

Fiber transmits light and is immune to electromagnetic interference.

Single-mode has a small core and supports long distances.

Multimode uses larger core for shorter links.

Select modules/connectors matching type and wavelength.

What carries data in optical fiber? → Light pulses.

What is a key advantage of fiber over copper? → Resistance to electromagnetic interference and support for long links.

Which fiber type is commonly used for longer distances? → Single-mode fiber.

Which fiber type typically serves shorter distances? → Multimode fiber.

Can single-mode and multimode optics be freely interchanged? → No; transceivers, fiber types, and optical specifications must match.

Peripheral Cables

USB-A, USB-B, USB-C are connector forms.

USB version describes data capabilities separately.

Thunderbolt carries high-speed data and sometimes display signals.

Serial/RS-232 common in legacy administration.

Power delivery capability depends on supported devices/cables.

Does USB-C guarantee USB4 or Thunderbolt? → No; connector type does not guarantee supported signaling.

What is USB Power Delivery used for? → Negotiating power delivery over supported USB connections.

What does a legacy DB-9 serial connector often carry? → RS-232 serial communications.

What can Thunderbolt provide? → High-speed data and often display/PCIe tunneling through compatible connections.

Why verify cable ratings before using a high-power USB-C charger? → Cable and device capabilities limit safe negotiated power.

Video Cables

HDMI and DisplayPort carry digital video and often audio.

VGA carries analog video.

DVI has digital and some analog variants.

USB-C video output requires supported alternate mode or compatible technology.

Which connector commonly carries analog video? → VGA.

Do HDMI and DisplayPort commonly carry audio along with video? → Yes, depending on equipment/support.

Is every USB-C port capable of external display output? → No; appropriate video/Alt Mode/Thunderbolt support is required.

What is DVI-D? → A digital-only DVI video interface.

What is an advantage of DisplayPort daisy chaining when supported? → Multiple monitors can connect via compatible Multi-Stream Transport equipment.

Storage Cables

SATA connects drives using distinct data and power connections.

eSATA exposes SATA for external devices.

Physical connectors and protocol capabilities matter.

SATA differs from PCIe/NVMe storage.

What does SATA stand for? → Serial ATA (Serial Advanced Technology Attachment).

How many separate common connectors does an internal SATA drive typically need? → SATA data and SATA power.

What is eSATA? → External SATA interface used to connect compatible external storage.

Does an M.2 SSD necessarily use SATA? → No; M.2 can support SATA or PCIe/NVMe depending on keying and system design.

Adapters and Converters

Adapters may change connector form while converters must translate incompatible signals.

USB hubs multiply available ports but share bus resources.

Display interfaces can require active conversion if signaling differs.

What is the difference between a passive adapter and an active converter? → A passive adapter reroutes compatible signals; an active converter translates between incompatible signal types.

Why might DVI-D to VGA require active conversion? → DVI-D is digital-only while VGA is analog.

What does a USB hub do? → Expands one USB connection into several downstream ports.

Can a connector adapter create unsupported features in a source device? → No; features depend on underlying interface and electronics.

Copper Connectors

RJ11 commonly used for telephone lines.

8P8C modular connector commonly called RJ45 for Ethernet.

F connector on coax.

DB-9 on serial.

Molex power in legacy PCs.

Know connector shape and purpose.

Which modular connector is typically used for Ethernet copper cabling? → 8P8C, commonly called RJ45.

Which connector commonly terminates coaxial cable Internet/TV lines? → F connector.

Which connector is commonly associated with analog telephone connections? → RJ11.

Which connector often appears on older serial ports? → DB-9.

What is a legacy Molex peripheral power connector? → Four-pin power connector used by certain older PC devices.

Fiber Connectors

LC compact with latch.

SC square push-pull.

ST round bayonet twist-lock.

Check fiber polish/type and duplex requirements.

Which fiber connector is small and uses a latch? → LC.

Which fiber connector has a square push-pull design? → SC.

Which fiber connector has a round bayonet-style twist lock? → ST.

What does duplex fiber mean? → Separate fibers may be used for transmit and receive paths.

Why must optics and fiber connectors be compatible? → Physical fit and optical signal specifications determine usable links.

An Overview of Memory

RAM is volatile working memory.

DIMM desktop modules differ from SO-DIMM laptop modules.

DDR generations have different electrical and physical compatibility.

Memory speed and capacity affect workloads.

What does RAM stand for? → Random Access Memory, volatile working storage.

Is RAM persistent when power is off? → No, ordinary system RAM is volatile.

What is a DIMM? → Dual In-line Memory Module, commonly desktop/server RAM form.

What is a SO-DIMM? → Small Outline DIMM, commonly used in laptops/compact systems.

Can DDR4 RAM go into a DDR5-only slot? → No; generations are physically and electrically incompatible.

What is dual-channel memory? → Using two memory channels to increase memory bandwidth with compatible configuration.

Memory Technologies

ECC detects/corrects certain errors and is common on servers.

Parity detects some data errors but does not independently correct them.

Multi-channel memory increases bandwidth.

Compatibility depends on CPU, board, RAM type and slot layout.

What does ECC stand for? → Error-Correcting Code memory.

What is ECC's primary purpose? → Detecting and correcting supported memory-bit errors.

What does parity memory do? → Detects certain data errors but does not inherently fix them.

What does dual-channel memory improve? → Memory bandwidth when properly configured.

A server must reduce silent memory corruption; what RAM technology is useful? → ECC RAM, if supported by platform.

Storage Devices

HDD uses rotating magnetic platters.

SSD uses flash memory.

NVMe protocol runs over PCIe and is not a physical form factor.

M.2 specifies a form factor.

SAS appears in enterprise environments.

Optical media and removable flash have different use cases.

What is the difference between HDD and SSD? → HDD uses moving magnetic disks; SSD uses solid-state memory with no rotating platter.

What is NVMe? → Non-Volatile Memory Express, a storage protocol generally using PCIe.

What is M.2? → A small card form factor/connector used by storage and other devices.

Are M.2 and NVMe synonyms? → No; M.2 describes form factor, NVMe describes a protocol.

What is SAS? → Serial Attached SCSI, commonly used for enterprise storage.

What is a benefit of an SSD for laptops? → Fast access and improved shock resistance.

What distinguishes an optical drive? → It reads/writes removable optical discs using light.

RAID

RAID 0 stripes for speed but lacks redundancy.

RAID 1 mirrors data.

RAID 5 distributed parity survives one drive failure.

RAID 6 double parity survives two drive failures.

RAID 10 uses mirrored sets striped together and needs at least four drives.

RAID is not a backup.

What does RAID 0 provide? → Striping/performance; no fault tolerance.

What does RAID 1 provide? → Mirroring; redundant copies on separate drives.

What is the minimum number of disks for RAID 5? → Three.

How many drive failures can RAID 6 generally tolerate? → Two, under supported independent-disk-failure conditions.

What is RAID 10? → Striping across mirrored pairs, often requiring at least four disks.

Does RAID replace offsite or independent backups? → No; RAID cannot protect against every form of data loss.

Motherboard Form Factors

ATX full-size desktop.

microATX smaller with fewer expansion possibilities.

Mini-ITX compact.

Case mounting, PSU, and expansion placement must match board dimensions.

What is ATX? → Advanced Technology eXtended, a common desktop motherboard form factor.

Which is generally smaller: ATX or microATX? → microATX.

What is Mini-ITX known for? → Very compact motherboards with limited physical expansion space.

What must match when replacing a motherboard? → Case form factor/support, CPU socket/chipset, RAM, power, and needed interfaces.

Can a case form factor limit GPU or cooler size? → Yes; space and clearance matter.

Motherboard Expansion Slots

PCIe is modern high-speed expansion interface.

Lane counts include x1 x4 x8 x16.

Physical slot length differs from negotiated electrical lanes.

Legacy PCI no longer common.

Check card and case clearance.

What does PCIe stand for? → Peripheral Component Interconnect Express.

What does PCIe x16 generally indicate? → A slot/link designed for up to 16 PCIe lanes depending on implementation.

What is commonly installed in a PCIe x16 slot? → A discrete graphics card.

Does a physical x16 slot always provide 16 electrical lanes? → No; motherboard design may wire fewer lanes.

What older expansion bus preceded PCIe? → PCI.

Motherboard Connections

24-pin ATX powers motherboard.

4/8-pin EPS CPU power separate.

SATA connectors attach compatible storage.

Front-panel headers connect buttons and LEDs.

USB/fan headers need correct wiring.

What powers most desktop ATX motherboard main logic? → The 24-pin ATX power connector.

Which connector commonly supplies CPU power? → A 4-pin or 8-pin EPS12V CPU power connector.

What do front-panel header pins connect? → Power/reset buttons and status LEDs on the case.

What is a motherboard fan header for? → Power and control of compatible system/CPU fans.

A PC does nothing when front power button pressed but PSU is good; what connector should be checked? → Front-panel power switch header/cable.

Motherboard Compatibility

CPU socket/chipset must match processor.

Intel and AMD use different socket families.

RAM type/generation and BIOS support affect compatibility.

Server boards may support ECC and management features.

Can any CPU fit any motherboard? → No; socket, chipset, firmware and power support must match.

Why check BIOS/UEFI support before a CPU upgrade? → Motherboard firmware may need updates for processor compatibility.

What RAM details must match the motherboard? → Generation, form factor, supported capacity/speeds and any ECC requirements.

What is a common enterprise motherboard feature? → ECC support or out-of-band management, depending on model.

The BIOS

BIOS/UEFI initializes hardware and launches boot process.

POST tests basic startup readiness.

Modern UEFI can support Secure Boot and GPT.

CMOS/RTC settings preserve date and firmware configuration as appropriate.

What does BIOS stand for? → Basic Input/Output System.

What is UEFI? → Unified Extensible Firmware Interface, a modern firmware interface.

What is POST? → Power-On Self-Test, startup hardware checks.

What does Secure Boot help enforce? → Boot-time validation of trusted signed boot components.

What type of disk partitioning is commonly associated with UEFI? → GPT, GUID Partition Table.

BIOS Settings

UEFI settings govern boot order, passwords, secure boot, virtualization, TPM, device enablement, and clock.

Record settings before changing.

CMOS clear resets settings but is not a substitute for data backup.

Where can you change boot device priority? → BIOS/UEFI setup.

What UEFI option might be required before running certain virtual machines? → Hardware virtualization support such as Intel VT-x or AMD-V.

What is a firmware administrator password? → A password restricting changes to BIOS/UEFI settings.

Why change Secure Boot configuration carefully? → It affects boot trust and can prevent unsupported bootloaders from starting.

What should you do before changing multiple unfamiliar firmware settings? → Record original values and research manufacturer guidance.

HSM and TPM

TPM securely supports cryptographic operations/key storage and boot measurements.

HSM is dedicated key-protection equipment used in enterprise systems.

Neither replaces full system security practices.

What does TPM stand for? → Trusted Platform Module.

What is a TPM useful for? → Protecting cryptographic keys, enabling measured boot and supporting disk encryption.

What does HSM stand for? → Hardware Security Module.

What is an HSM commonly used for? → Dedicated protection and use of cryptographic keys in enterprise operations.

Does TPM itself encrypt every file automatically? → No; software such as full-disk encryption uses TPM capabilities as part of a security design.

CPU Features

32-bit vs 64-bit affects address width and compatibility.

Multiple cores run tasks concurrently.

ARM emphasizes efficient architecture used in mobile and other systems.

CPU type must match OS/app architecture.

What is the main distinction between 32-bit and 64-bit CPUs? → Register/address architecture and supported software/memory addressing.

What is a CPU core? → An execution unit capable of processing instruction streams.

What is ARM? → A processor architecture family common in mobile/energy-efficient systems.

Why verify OS architecture before installing an app? → Software must be compatible with the processor and OS architecture.

Does doubling CPU cores guarantee double performance? → No; software parallelism, workload and other bottlenecks matter.

Expansion Cards

Graphics cards render video.

NICs add network interfaces.

Sound cards manage audio.

Capture cards ingest external video.

Driver installation is needed for OS device support.

What expansion card adds Ethernet capability? → A network interface card (NIC).

What expansion card is used for hardware-accelerated graphics output? → Graphics card/GPU.

What does a video capture card do? → Receives video from external inputs for recording/processing.

Why install the manufacturer's correct device driver? → The OS needs compatible software to communicate with hardware features.

What precaution helps avoid damage when adding cards? → Power off, disconnect power, and use safe ESD practices.

Cooling

Heat sinks draw heat from chips.

Thermal paste fills microscopic interface gaps.

Fans move air through case.

Passive cooling no fan.

Liquid cooling transfers heat to radiator.

Poor airflow/dust causes overheating and throttling.

What is the purpose of thermal paste? → Improve thermal contact between CPU/GPU and heat sink by filling microscopic gaps.

What does a heat sink do? → Transfers heat away from a component into a larger surface area.

What does CPU thermal throttling mean? → The CPU reduces performance to limit temperature.

What maintenance often helps an overheating desktop? → Safely remove dust and verify fans and airflow.

What is passive cooling? → Dissipating heat without active fans or pumps.

What is a risk of improperly installed CPU cooler? → Overheating, crashes or shutdowns.

Computer Power

PSUs convert AC wall power to DC rails.

Wattage headroom matters.

80 PLUS efficiency ratings describe AC-to-DC efficiency at test loads, not build quality.

Redundant PSUs reduce single-source failure.

Voltage selection and regional specifications require care.

What does a computer PSU do? → Converts incoming AC power into regulated DC power for components.

What does PSU wattage rating indicate? → Maximum rated output power under specified conditions.

Does an 80 PLUS rating guarantee PSU reliability? → No; it relates primarily to conversion efficiency.

Why use redundant power supplies on a server? → To support uptime if one PSU fails.

What should you verify before upgrading a GPU? → PSU capacity and required power connectors.

Should an untrained technician open a PSU housing to repair it? → No; internal capacitors can retain dangerous charge.

Multifunction Devices

MFD combines print scan copy fax or other functions.

Configure interfaces, drivers, scanning methods, duplex, collation, and security.

PCL/PostScript are page description languages.

Secure print holds jobs pending authentication.

What is an MFD? → Multifunction device combining functions such as printing, scanning and copying.

What is duplex printing? → Printing on both sides of a sheet.

What is collating? → Outputting multi-page sets in page order.

What is secure printing? → Holding a print job until the authorized user releases it.

What is PCL? → Printer Command Language, a printer page-description/control language.

Why might a scanner use an automatic document feeder? → To scan multi-page documents without placing pages one at a time.

Laser Printer Maintenance

Laser printer process charges, exposes, develops, transfers, fuses, cleans.

Fuser bonds toner using heat/pressure.

Replace toner and maintenance rollers as recommended.

Print quality clues distinguish imaging drum and fuser problems.

What part bonds toner to paper? → Fuser assembly using heat and pressure.

What is the imaging drum's role? → Forms an electrostatic image that attracts toner.

What is the transfer stage for? → Moving toner image from imaging surface to paper.

If toner rubs off after printing, what component is suspect? → Fuser, after ruling out incompatible media/settings.

What should be done after replacing laser printer consumables? → Follow manufacturer's calibration, cleaning, and maintenance procedure.

Inkjet Printers

Inkjet prints liquid ink through microscopic nozzles.

Print head and ink cartridges vary by design.

Carriage positions heads.

Feed rollers move paper.

Clogged nozzles cause missing lines/colors.

How does inkjet printing create an image? → Sprays tiny droplets of liquid ink onto paper.

What might cause streaks or missing colors on an inkjet? → Clogged print head nozzles or low/failed ink supply.

What moves the print head across paper in many inkjets? → Carriage mechanism and belt.

What part grips and moves paper? → Feed rollers.

Inkjet Printer Maintenance

Nozzle cleaning and calibration resolve many quality issues.

Replace cartridges safely and use compatible ink.

Paper paths/rollers can cause jams.

Avoid excessive cleaning cycles wasting ink.

What maintenance addresses clogged inkjet nozzles? → Print head cleaning cycle.

What does inkjet alignment/calibration address? → Misaligned output, color placement or print registration issues.

What are common causes of inkjet paper jams? → Debris, damaged/incorrect paper, misfeeds or worn rollers.

Why should you avoid needless repeated print-head cleaning? → It consumes ink and may not address other problems.

Thermal Printers

Thermal printing commonly heats coated paper to create dark marks.

Common in receipts and labels.

Supplies must suit printer type.

Heat and sunlight can damage thermal output.

How does direct thermal printing work? → A print head heats specially coated paper to form marks.

Where are thermal printers commonly used? → Receipt counters and label printing.

Does direct thermal printing require toner or ink cartridges? → No; it uses heat-sensitive media.

Why can a thermal receipt fade? → Heat, sunlight, and paper chemistry degrade the image.

Thermal Printer Maintenance

Use correct thermal rolls and direction.

Clean print head gently per manufacturer.

Remove debris from feed.

Thermal media may be damaged by excess heat.

What happens if direct thermal paper is loaded backward? → The heating elements may not print on the coated side.

What should you clean on a thermal printer with streaks? → Thermal print head/feeding path as directed by manufacturer.

What consumable does a direct thermal printer generally require? → Compatible thermal paper or labels.

Why store thermal rolls away from heat? → Heat can darken or degrade thermal-sensitive coating.

Impact Printers

Impact/dot-matrix printer strikes inked ribbon against paper.

Tractor feed handles continuous forms.

Useful for multipart carbon-copy forms.

Loud mechanical printing compared with laser/inkjet.

What physical action makes a dot-matrix printer print? → Pins in print head strike inked ribbon against paper.

Which printer type is especially suitable for multipart forms? → Impact/dot-matrix.

What is a tractor feed? → Mechanism moving continuous perforated paper using sprocket holes.

Why are impact printers generally noisier? → Mechanical contact strikes ribbon and paper.

Impact Printer Maintenance

Replace ribbon when output fades.

Replace print head if pins fail.

Inspect tractors and continuous forms alignment.

Power down for appropriate maintenance.

A dot-matrix printer output is faint; what consumable is likely worn? → Ink ribbon.

Several vertical dots are always missing; what hardware may be failing? → Print head pins.

What feeds continuous multipart paper? → Tractor feed mechanism.

What should be checked if continuous paper skews? → Tractor alignment and feed-path setup.

Virtualization Concepts

VM is isolated virtualized guest on physical host.

Multiple OSs can run concurrently.

Useful for testing, sandboxing, software compatibility.

Guest resource needs compete for physical CPU RAM storage.

What is a virtual machine? → A software-defined computer running a guest OS on a host system.

What is a host versus guest? → Host supplies physical resources; guest is the virtualized OS/environment.

Why use virtualization for testing? → To isolate experiments from production systems and reproduce configurations.

What is sandboxing? → Running code in a more restricted/isolation environment.

Can virtual machines share physical host hardware? → Yes, through the hypervisor's resource management.

Virtualization Services

Type 1 hypervisor runs directly on hardware.

Type 2 runs above host OS.

VT-x/AMD-V supports hardware virtualization.

VDI delivers centralized desktop environments.

Containers share host OS kernel unlike full VMs.

What is a Type 1 hypervisor? → A bare-metal hypervisor running directly on hardware.

What is a Type 2 hypervisor? → A hypervisor application running on a host operating system.

What is VDI? → Virtual Desktop Infrastructure: centrally hosted virtual desktops delivered to users.

What differentiates containers from full virtual machines? → Containers generally share the host OS kernel rather than running a full separate guest kernel.

What BIOS/UEFI feature may need enabling for virtualization? → CPU virtualization support, such as Intel VT-x or AMD-V.

Cloud Models

IaaS exposes virtual infrastructure, PaaS provides managed app platform, SaaS delivers ready software.

Public resources provider-operated.

Private cloud dedicated to one organization.

Hybrid combines distinct environments.

What does IaaS stand for? → Infrastructure as a Service: rented compute/storage/network building blocks.

What does PaaS stand for? → Platform as a Service: managed application development/runtime environment.

What does SaaS stand for? → Software as a Service: provider-managed software used through network access.

What is a public cloud? → Cloud resources made available to customers by a provider.

What is a private cloud? → Cloud infrastructure dedicated to a single organization.

What is a hybrid cloud? → An architecture combining distinct environments with integration.

Cloud Characteristics

Measured/metered service tracks usage.

Elastic resources scale with demand.

High availability uses resilient design.

Multi-tenancy shares provider platform while isolating customers.

Cloud files sync across clients, though replication is not a backup by itself.

What is cloud elasticity? → Ability to provision/release resources to match changing demand.

What is metered cloud usage? → Measuring service consumption for reporting or billing.

What is cloud multitenancy? → Multiple customers share underlying provider resources with logical isolation.

What does high availability aim for? → Reducing downtime through resilient architecture and redundancy.

Does file synchronization replace backups? → No; unwanted deletion or corruption can synchronize too.

Troubleshooting Hardware

Use systematic methodology: identify symptoms, hypotheses, tests, repair, verify, document.

No power differs from no display.

POST beeps/LED codes inform failure.

Overheating causes shutdown/throttling.

BSoD may indicate drivers hardware or software.

A PC shows no power lights and no fans; what should you check first? → Power source, cable, PSU switch, outlet and basic external connections.

A PC powers on but displays nothing; what category of checks is appropriate? → Monitor/input/cable, GPU/display output, and POST indicators.

What does POST stand for? → Power-On Self-Test.

What are common overheating symptoms? → Unexpected shutdowns, throttling, high fan speed and instability.

What should you do after implementing a fix? → Verify full functionality and document findings.

Does a blue screen always mean failed RAM? → No; it can result from drivers, hardware or software faults.

Troubleshooting Storage Devices

Clicking/grinding HDD suggests mechanical damage.

SMART provides drive health warnings, not guarantees.

Back up data before destructive repairs.

RAID degraded state indicates lost redundancy.

Disk full can cause slowdown.

IOPS is I/O operations per second.

A hard drive makes repeated clicking sounds; what is a likely concern? → Mechanical failure; prioritize data protection/replacement.

What does S.M.A.R.T. stand for? → Self-Monitoring, Analysis and Reporting Technology.

What does degraded RAID usually mean? → Array is operating with reduced redundancy, often after a drive failure.

What does IOPS mean? → Input/Output Operations Per Second, a storage performance measure.

Why back up data before disk repair operations? → Some changes can permanently destroy or overwrite data.

A drive isn't detected by firmware; what should you inspect? → Drive power/data connection, interface, firmware detection, and drive health.

Troubleshooting Display Issues

Incorrect input source/cable causes black screen.

Fuzzy image can come from non-native resolution.

Dead pixels are permanent display points.

Burn-in affects emissive displays.

Flicker may be refresh cable or power.

Projector bulbs have life limits.

A monitor says 'No signal' while PC runs; what should you inspect? → Monitor source/input selection, video cables, output port, and PC POST status.

What often causes a fuzzy LCD image? → Non-native resolution or scaling configuration.

What is a dead pixel? → A display pixel/subpixel that fails to operate correctly.

What is image burn-in? → Persistent image retention/damage, especially on certain emissive displays.

What might cause intermittent screen flicker? → Cable, refresh setting, driver, power or display hardware issues.

Troubleshooting Mobile Devices

Charging faults: cable, adapter, port, battery.

Swollen battery is hazardous and should not be punctured.

Cracked screen vs digitizer failure.

Liquid damage calls for power-off and service policy.

Overheating often from workload/battery/ventilation.

Cursor drift may involve input.

A phone will not charge; what safe checks come first? → Known-good power adapter/cable, power source, and charging-port inspection.

What should you do with a swollen lithium-ion battery? → Stop using/charging it and arrange safe professional service/disposal; do not puncture.

What's the difference between a screen and digitizer? → Display shows images; digitizer detects touch input.

After suspected liquid damage, should you immediately power on to test? → No; power down and follow repair guidance to reduce further damage.

What might cause laptop touchpad cursor drift? → Contamination, sensitivity settings, drivers, or hardware faults.

Troubleshooting Networks

Check physical link, IP/subnet/gateway, DNS, DHCP, Wi-Fi strength, interference.

Latency is delay.

Jitter variation in delay.

Packet loss affects calls.

Port flapping means repeated link state changes.

Troubleshoot from local to remote.

A user has 169.254.x.x IP and no connectivity; what service might be failing? → DHCP or reachability to DHCP.

Website works by IP but not by hostname; what should be checked? → DNS.

What is network latency? → Time delay in transmitting data between endpoints.

What is jitter? → Variation in packet delay, important for voice/video.

What is packet loss? → Packets that fail to arrive, potentially reducing performance or quality.

What is port flapping? → A network interface repeatedly transitions up and down.

What physical checks come before extensive software diagnosis? → Cables, link indicators, wireless connection/signal and device power.

Troubleshooting Printers

Print queue stuck may require service/spooler review.

Garbled output may mean incorrect driver/page language.

Repeated marks often roller/drum issue.

Paper jams caused by worn rollers/debris.

Toner not fused indicates fuser.

Thermal faded due to heating/paper.

A print job remains stuck in queue; what should you investigate? → Spooler, printer status/connectivity, queue and driver.

Printed page has nonsensical symbols; what is a likely cause? → Wrong/corrupt driver or mismatched printer language.

Toner easily rubs off; what assembly should you check? → Fuser and media settings.

A printer repeatedly jams at one location; what should you inspect? → Paper path, pickup/registration rollers and obstructions.

A printer is reachable but prints nothing; what should you check? → Queue, errors, supplies, and driver/port settings.

Print quality has repeating defects at regular intervals; what parts may cause it? → Rotating drum or roller components, depending on spacing.