CompTIA A+ Concept Review

Overview

This chapter is about laptops, phones, and tablets: which parts a technician can replace, which accessories and ports they use, and how they connect to networks and to each other. Questions are usually short scenarios, such as a user who cannot pair a headset or a laptop that needs more memory.

Many laptop parts can be swapped, such as the battery, keyboard, memory (small SO-DIMM modules), and M.2 storage drives. The Wi-Fi antenna wires usually run through the display, which is why a damaged lid can cause weak wireless signal. Always follow the maker's service steps, because laptop parts are small and often held by hidden screws and ribbon cables.

Mobile devices connect in several ways. Bluetooth links nearby accessories after a pairing step. NFC works only when devices nearly touch and is used for tap-to-pay. A hotspot shares a phone's cellular data connection with other devices over Wi-Fi. Companies use mobile device management (MDM) to push settings, apps, and security rules to phones they manage.

Overview

This chapter covers how devices talk to each other on a network. You need to know common port numbers, the job of each network device, Wi-Fi basics, IP addressing, and the services that make a network work, such as DHCP and DNS. It is a big part of Core 1, and it is also the base for the troubleshooting chapter.

Each network service listens on a port number. For example, SSH uses 22, DNS uses 53, HTTP uses 80, HTTPS uses 443, and Remote Desktop uses 3389. TCP checks that data arrives and resends lost pieces, while UDP is faster but does not check, which suits things like streaming and DNS lookups.

DHCP hands out IP addresses automatically, and DNS turns names like www.example.com into IP addresses. If a Windows PC cannot reach a DHCP server, it gives itself an APIPA address that starts with 169.254 and can only talk to the local network. Private address ranges such as 192.168.x.x, 10.x.x.x, and 172.16.x.x to 172.31.x.x are used inside homes and offices.

Devices each have a role: a switch connects devices inside one network, a router connects different networks, an access point adds Wi-Fi, and a firewall filters traffic. Technicians use tools such as a cable tester, a crimper, a punchdown tool, a toner probe, and a Wi-Fi analyzer to build and check networks.

Overview

This chapter covers the parts inside and around a computer: cables and connectors, memory, storage, motherboards, CPUs, power supplies, and printers. Many questions ask which part or cable fits a job, or how to set up storage so data is safe.

Memory (RAM) holds data the computer is working on and is cleared when power is off. Desktop memory modules are DIMMs and laptop modules are SO-DIMMs, and the module type must match the motherboard, such as DDR4 or DDR5. Installing matching modules in the right slots lets the board use dual-channel mode for better speed.

Storage keeps data when power is off. Hard disk drives (HDDs) use spinning platters, while solid-state drives (SSDs) have no moving parts and are much faster. NVMe SSDs use the PCIe bus and are faster than SATA SSDs. RAID combines several drives: RAID 0 stripes data for speed with no protection, RAID 1 mirrors two drives, RAID 5 stripes data with parity across at least three drives, RAID 6 uses two parity blocks across at least four drives, and RAID 10 stripes across mirrored pairs and needs at least four drives.

The power supply turns wall AC power into the DC voltages the parts need, and its wattage must cover all the parts. Firmware (BIOS or UEFI) settings control boot order, Secure Boot, the TPM chip, and virtualization support. Laser printers use a fuser to melt toner onto paper, so pages that smear mean the fuser needs attention.

Overview

This chapter explains how one physical computer can run many virtual computers, and how companies rent computing from cloud providers. It is the smallest part of Core 1, but the terms come up often in real help desk work.

A hypervisor is the software that runs virtual machines (VMs). A Type 1 hypervisor runs directly on the hardware and is used in data centers. A Type 2 hypervisor runs as an app on top of a normal operating system and is handy for testing on a desktop. VMs need enough CPU, memory, and storage on the host, and the CPU's virtualization support must be turned on in firmware. Containers are lighter: they share the host's operating system kernel and package only an app and what it needs.

Cloud services come in three main models. In Infrastructure as a Service (IaaS) you rent virtual servers and storage and manage the operating system yourself. In Platform as a Service (PaaS) you get a ready platform to run your own code. In Software as a Service (SaaS) you simply use finished software over the internet. Clouds can be public, private, hybrid (a mix), or community (shared by groups with the same needs). Key cloud features include rapid elasticity, which adds or removes resources as demand changes, and metered use, where you pay for what you use.

Overview

This is the largest part of Core 1. It asks you to use CompTIA's troubleshooting steps on real problems with PCs, laptops, phones, storage, printers, and networks. Most questions describe what a user sees and ask for the most likely cause or the best next step.

The troubleshooting steps are: identify the problem, establish a theory of probable cause, test the theory, establish a plan of action and put the fix in place, verify full system functionality and add preventive measures, and document what you found and did. While identifying the problem, ask the user questions, check for recent changes, and back up data before you change anything. If a theory turns out wrong, form a new one or escalate.

Some symptoms point clearly to a cause. A PC that shuts off after running for a while may be overheating. A clock that resets after power is removed points to the CMOS battery. Grinding or clicking from a hard drive warns of failure, so back up at once. On networks, a 169.254 address points to a DHCP problem, and being able to reach an IP address but not a name points to DNS.

Overview

This chapter is the largest part of Core 2 along with security. It covers Windows editions and installs, the built-in Windows tools, command-line commands, file systems, and the basics of macOS and Linux. Expect questions that ask which tool or command fits a task.

Windows Home and Pro differ in business features. Pro can join a domain, use Group Policy Editor, host Remote Desktop sessions, and use BitLocker drive encryption, while Home cannot. Useful tools include Task Manager for running apps and startup items, Event Viewer for logs, Device Manager for drivers, Disk Management for partitions, and Services for background services.

At the command line, ipconfig shows network settings, ping tests reachability, tracert shows the path to a host, chkdsk checks a disk, sfc /scannow repairs system files, and gpupdate /force applies Group Policy right away. NTFS is the main Windows file system and supports permissions and large files. FAT32 is widely compatible but cannot hold one file over 4 GB, and exFAT is a good choice for large files on flash drives.

On macOS, Time Machine makes backups, FileVault encrypts the disk, and Keychain stores passwords. On Linux, ls lists files, cd changes folders, chmod changes permissions, sudo runs a command with administrator rights, and apt or dnf installs software, depending on the distribution.

Overview

This chapter covers how to keep people, devices, and data safe. It ranges from locks and badges to passwords, multifactor authentication, Wi-Fi security, malware, and social engineering. It is as large as the operating systems chapter on Core 2.

Strong security starts with who you are. Multifactor authentication (MFA) asks for two or more different kinds of proof: something you know (a password), something you have (a phone or token), or something you are (a fingerprint). The principle of least privilege means each user gets only the access needed for the job. For Wi-Fi, use WPA3 or WPA2 with AES, change default router passwords, and keep firmware up to date.

Malware comes in many forms. Ransomware encrypts files and demands payment, a trojan hides inside software that looks useful, a worm spreads by itself across networks, a keylogger records keystrokes, and a rootkit hides deep in the system. Social engineering tricks people instead of machines: phishing by email, vishing by phone, smishing by text, and tailgating by following someone through a secured door.

When removing malware, first confirm the symptoms, then quarantine the infected system from the network. In Windows, turn off System Restore so old restore points do not bring the infection back, then clean the system with updated tools, schedule scans and updates, turn System Restore back on with a fresh restore point, and teach the user how to avoid the problem.

Overview

This chapter is about fixing problems with Windows, apps, and mobile software, and spotting signs of malware. Questions describe a symptom, such as a slow PC or a crashing app, and ask what to check or which tool to use first.

For Windows problems, start with the least disruptive fix. Restart the computer or the app, check for updates, and look in Event Viewer for errors. Safe Mode starts Windows with only basic drivers and services, which helps show whether a driver or startup program is the cause. System Restore rolls system files and settings back to an earlier point without touching personal files. If one user's settings are damaged, rebuilding the user profile can help.

Malware often shows itself through browser redirects, pop-ups, a changed home page, missing files, strange accounts, or a security app that has been turned off. Certificate warnings on many trusted sites can mean the computer's date and time are wrong. On phones, apps that crash or drain the battery can often be fixed by updating, clearing the app's cache, or reinstalling the app.

Overview

This chapter covers how a professional technician works: tracking tickets, writing documentation, managing changes, making backups, working safely, protecting the environment and private data, and talking with customers. Many questions ask for the best or most professional action.

Good records make support easier. Tickets record the user, the problem, the steps taken, and the result. Asset tags and an inventory track equipment. Changes to systems follow change management: write a request with the purpose and scope, assess the risk, plan a rollback, get approval, and test before going live.

Backups protect data. A full backup copies everything. An incremental backup copies only what changed since the last backup of any kind, and a differential copies everything that changed since the last full backup. A common rule is 3-2-1: three copies of data, on two kinds of media, with one copy off-site. Test restores, because an untested backup may not work.

Safety comes first. Unplug equipment before opening it, use an ESD wrist strap to protect parts from static, and lift with your legs. Use a safety data sheet (SDS) to learn how to handle chemicals like toner. Protect private data, respect software licenses, explain things without jargon, and do not paste confidential company data into public AI tools.