CompTIA A+ core 1

What is the difference between a public and private IP address?

Private IPs are used within internal networks and aren't routable on the internet; public IPs are used for external communication and are routable.

What is DHCP used for?

Automatically assigns IP addresses and other network configurations to devices on a network.

What port does FTP use?

Ports 20 and 21

What port does Remote Desktop Protocol (RDP) use?

Port 3389

What is a MAC address?

A unique identifier assigned to a network interface card (NIC); it's hardware-based and unchangeable.

What is a subnet mask used for?

Determines which portion of an IP address is the network and which is the host.

What is NAT (Network Address Translation)?

Translates private IP addresses to a public IP to allow multiple devices to share one external IP.

What is the purpose of a router?

Connects multiple networks and directs data between them.

What is the function of a switch?

Forwards data only to the specific device it is intended for on a local network.

What does a modem do?

Modulates and demodulates digital and analog signals to enable internet over cable/DSL.

What is a patch panel used for?

Organizes and connects networking cables in a structured cabling setup.

What is a crimper tool used for?

Attaches connectors to the ends of cables, like RJ45 plugs.

What cable type uses copper and has RJ-45 connectors?

Twisted-pair Ethernet (Cat5e, Cat6)

What are two types of fiber optic cable?

Single-mode (long distances), multi-mode (shorter distances)

What tool would you use to trace a network cable's path?

Tone generator and probe (toner probe kit)

What is APIPA and when is it used?

Automatic Private IP Addressing (169.254.x.x); assigned when DHCP fails.

What wireless standard supports up to 6.9 Gbps and operates on both 2.4 GHz and 5 GHz bands?

802.11ac

What is a typical use case for satellite internet?

Remote or rural areas with no wired broadband access.

What connection type should be used for someone who travels and is often in rural areas with poor signal?

Satellite (not hotspot - hotspot depends on cellular signal strength)

What is the purpose of a Hub?

A hub will take data that it receives from the server and will transmit the data to every device connected to the hub.

what is the maximum theoretical speed of 802.11ac?

Up to 6.9 Gbps.

What's the typical range of 2.4 GHz Wi-Fi indoors?

About 150 feet (45 meters)

What's the typical range of 5 GHz Wi-Fi indoors?

About 45 feet (13 meters)

What type of internet connection uses your phone lines but allows simultaneous voice and data?

DSL ( Digital Subscriber Line)

What type of internet connection provides high speed via cable TV infrastructure?

Cable

What tool is used to test the functionality and quality of Ethernet cables?

Cable tester

What does a punch-down tool do?

Connects wires into a patch panel or keystone jack.

What does a loopback plug test?

Whether a port (usually network or serial) is functioning correctly.

What is the difference between DDR3 and DDR4 RAM?

DDR4 is faster, uses less power, and has a higher bandwidth than DDR3.

What is ECC memory used for?

Error-Correcting Code memory detects and corrects single-bit memory errors, often used in servers.

What is the function of SODIMM RAM?

It is a smaller form factor of RAM used in laptops and small form-factor PCs.

What is the difference between single-channel and dual-channel memory?

Dual-channel allows two memory modules to be accessed simultaneously, doubling the memory bandwidth.

What connector carries digital video and audio signals and supports high resolutions?

HDMI (High-Definition Multimedia Interface)

What is the main difference between VGA and DVI?

VGA is analog; DVI is digital (or hybrid).

Which display technology is commonly used in modern laptops for thin displays and better color?

IPS (In-Plane Switching) LCD panels

What are the benefits of OLED displays?

Better contrast, faster refresh, and thinner displays with no backlight needed.

What is NVMe used for?

It connects SSDs directly to the PCIe bus for much faster read/write speeds than SATA.

What is the purpose of a RAID array?

Combines multiple drives for redundancy, performance, or both.

What is the purpose of the chipset on a motherboard?

It manages communication between the CPU, RAM, storage, and peripherals.

What is an ATX motherboard?

A standard full-sized motherboard with more expansion and RAM slots.

What is the main purpose of PCIe slots?

To connect high-speed components like GPUs and NVMe drives.

What does a riser card do?

Allows expansion cards to be mounted parallel to the motherboard, used in low-profile PCs.

What does a modular PSU allow?

You can attach only the cables you need for cleaner cable management.

What rating ensures a power supply is energy efficient?

80 PLUS certification (e.g., 80 PLUS Bronze, Silver, Gold)

Why is it important to match wattage when replacing a PSU?

Insufficient wattage can lead to system instability or failure to boot.

What should you do before installing a new expansion card?

Power down the system, unplug it, and discharge any static electricity.

What is a POST test?

Power-On Self Test - a diagnostic test run by firmware when a PC is powered on.

What tool is used to prevent ESD damage when working inside a PC?

An antistatic wrist strap or mat.

What is the purpose of standoffs when installing a motherboard?

They prevent the motherboard from touching the case directly, avoiding a short circuits.

What should you do after installing a new component and booting the system?

Enter BIOS/UEFI to verify the hardware is recognized correctly.

What BIOS setting often needs to be changed when installing an NVMe SSD?

Boot order or enabling NVMe/PCIe support.

What does memory clock speed affect?

How fast data can be read from or written to RAM — higher speeds improve performance.

What is CAS latency in RAM?

Column Access Strobe — it measures the delay between a request and data availability; lower is faster.

What is memory channel configuration, and why does it matter?

It refers to how RAM modules are accessed — dual/triple/quad channel improves performance by allowing simultaneous access.

What RAID level offers both performance and redundancy by striping and mirroring data?

RAID 10 (1+0)

Which RAID level offers the best performance but no redundancy?

RAID 0 (striping only)

What is required to install and boot from an NVMe SSD?

A compatible motherboard with an M.2 PCIe slot and UEFI firmware with NVMe boot support.

What is the advantage of NVMe over SATA SSDs?

NVMe uses the PCIe interface, offering significantly higher read/write speeds.

A technician is setting up a system that requires high performance and moderate redundancy. Which RAID level would be most suitable?

RAID 10

What are common consumables for laser printers?

Toner, imaging drum, fuser assembly, transfer belt, and pickup rollers.

What maintenance does an inkjet printer often require?

Replacing ink cartridges, cleaning print heads, and aligning the print nozzles.

What does the transfer belt do in a laser printer?

It transfers toner from multiple cartridges onto paper in color printing.

What is calibration in the context of printers?

A process to align print heads or colors for accurate output.

What should you do after replacing a printer cartridge?

Run a calibration or alignment utility via printer settings or software.

What is the main purpose of virtualization?

To run multiple operating systems or virtual machines (VMs) on a single physical device.

What type of software is used to create and manage virtual machines?

A hypervisor.

What are the two main types of hypervisors?

Type 1 (bare-metal) and Type 2 (hosted).

What is a Type 1 hypervisor?

A hypervisor that runs directly on the hardware without a host OS (e.g., VMware ESXi, Microsoft Hyper-V).

What is a Type 2 hypervisor?

A hypervisor that runs on top of a host OS (e.g., VirtualBox, VMware Workstation).

What is the benefit of using virtual machines (VMs)?

Efficient resource use, easy backup and recovery, isolated environments, and scalability.

What are the three main cloud service models?

IaaS (Infrastructure as a Service), PaaS (Platform as a Service), and SaaS (Software as a Service).

What is IaaS?

Infrastructure as a Service — provides virtualized hardware like servers, storage, and networking.

What is SaaS?

Software as a Service — delivers software applications over the internet (e.g., Google Docs, Microsoft 365).

What is PaaS?

Platform as a Service — provides a platform for developers to build, test, and deploy apps.

What is a private cloud?

A cloud environment used exclusively by one organization, offering more control and security.

What is a public cloud?

A cloud environment shared by multiple customers, maintained by a third-party provider.

What is a community cloud?

A cloud infrastructure shared by several organizations with common interests

What is the difference between cloud computing and virtualization?

Virtualization creates multiple simulated environments on one machine; cloud computing delivers services over the internet using virtualization.

What is the difference between metered and non-metered cloud services?

Metered services charge based on usage (e.g., storage space, CPU time, bandwidth).

Non-metered services offer flat-rate or unlimited usage regardless of consumption.

When would a metered cloud service be preferred?

When clients have unpredictable or infrequent resource usage — they pay only for what they use (cost-efficient for startups or seasonal workloads).

When would a non-metered service be more appropriate?

For businesses with consistent, heavy usage — they benefit from predictable billing and no usage limits.

What is sandboxing in virtualization or cloud environments?

A method to run applications in isolated environments to prevent them from affecting the host system or other apps.

What's a real-world use of sandboxing?

esting untrusted software

Running malware analysis

Preventing browser-based exploits

Running beta versions without impacting the OS

A developer wants to quickly deploy and test web applications with built-in scalability. Which service is best?

PaaS (Platform as a Service) — offers ready-made environments with tools and scalability for development.

A business needs full control over their servers and storage in the cloud. Which cloud model is best?

IaaS — gives full access to virtualized hardware for maximum customization and control.

A startup with no IT department wants to use software like email and word processing without managing installations. Best model?

SaaS — offers out-of-the-box solutions maintained by the provider.

A company needs to host sensitive customer data and comply with strict regulations. Which deployment model should they choose?

Private cloud — offers more control and better compliance options.

A client has a fluctuating workload and needs to scale quickly during peak seasons. What cloud model is ideal?

Public or hybrid cloud — allows flexibility and scalability during demand spikes.

A technician needs to run a suspicious program without risking the host OS. What should they use?

A sandboxed VM or container — isolates the app from the host environment.

Which virtualization feature allows saving the VM state and reverting back later?

Snapshots — useful for testing or rollback before updates.

How does virtualization improve disaster recovery?

VMs can be backed up, cloned, or moved to other hosts easily — speeding up recovery after failure.

What is the likely cause if a PC powers on but there is no display?

Check for loose video cables, faulty GPU, or RAM not seated properly.

What causes a burning smell or smoke from a device?

Likely short circuit, power supply failure, or electrical component burnout — immediately power off and disconnect.

A computer randomly shuts down. What could be the issue?

Overheating, failing PSU, faulty RAM, or thermal paste dried out.

Why might a user hear grinding noises from their desktop?

Failing hard drive or fan bearing issues.

What causes a dim screen on a laptop even when brightness is turned up?

Faulty inverter (older laptops) or backlight failure.

What causes flickering or distorted images on a monitor?

Loose video cable, outdated GPU driver, or electromagnetic interference.

What does APIPA address (169.254.x.x) indicate?

The system couldn't reach a DHCP server — check network cable or router.

A user can ping internal IPs but not external websites. Cause?

DNS issue or missing default gateway.

What are the 6 steps in the CompTIA troubleshooting process?

1. Identify the problem

2. Establish a theory

3. Test the theory

4. Establish a plan

5. Verify full system functionality

6. Document findings