CompTIA A+ Core 1 练习

The CPU executes instructions and performs calculations, so it is often called the brain of the computer. RAM stores temporary data, and the motherboard connects components, but neither processes instructions like the CPU.

RAM temporarily holds data and instructions for programs that are currently running. It is fast but volatile, so data is lost when the computer powers off. Permanent storage belongs to drives.

Firmware such as BIOS or UEFI is stored in non-volatile flash memory or ROM. It keeps its contents when power is off. RAM and cache are volatile, and virtual memory uses the hard drive.

The power supply converts alternating current from the wall into the direct current voltages used by internal components. Cooling, storage, and network connections are handled by other parts.

Modern NVMe SSDs commonly use the M.2 form factor, which connects directly to the motherboard. VGA and HDMI carry video, while RJ45 is used for Ethernet networking.

An SSD uses flash memory and has no moving parts. HDDs, optical drives, and tape drives use spinning media or moving mechanisms, which makes them more sensitive to shock.

RAID 1 mirrors data across two or more drives, so one copy protects against a single drive failure. RAID 0 uses striping for speed but provides no redundancy.

RAID 0 spreads data across drives to improve performance, but it provides no redundancy. If one drive fails, data can be lost. RAID 1 mirrors data instead.

Laser printers use toner powder, heat, and a drum to create images. Inkjet printers use liquid ink, while thermal and dot matrix printers use different technologies.

Inkjet printers spray liquid ink onto paper through tiny nozzles. Laser printers use toner, and impact printers use ribbons or pins.

POST is the Power-On Self-Test that runs when a computer starts. It checks essential hardware before the operating system loads. The other options are not real terms.

Desktop computers commonly use DIMM modules. Laptops use the smaller SODIMM form factor. M.2 and PCIe are not RAM form factors.

Graphics cards are usually installed in a PCIe x16 slot because it provides high bandwidth. PCI is older and slower, while M.2 and SATA are for storage.

A CPU cooler removes heat from the processor so it stays within safe operating temperatures. It does not improve RAM speed or provide power or network connectivity.

The motherboard is the main circuit board that connects the CPU, RAM, storage, and expansion cards. Internet, backup, and antivirus functions are provided by other hardware and software.

BIOS and UEFI firmware initialize hardware and hand control to the operating system during startup. They do not defragment drives, manage email, or encrypt all traffic.

HDMI carries digital video and audio to a monitor. Ethernet connects networks, USB-A connects peripherals, and SATA connects storage drives.

A surge protector absorbs or diverts excess voltage to protect connected devices. It does not improve Wi-Fi, convert power for internal components, or cool the case.

This statement is false. SSDs use flash memory and have no moving parts. Spinning magnetic platters are found in traditional hard disk drives.

Laptops use the smaller SODIMM RAM form factor. Desktop motherboards use full-size DIMM modules. SODIMM modules fit in compact spaces inside portable computers.

HTTPS uses TCP port 443 for encrypted web traffic. Port 80 is used by plain HTTP, and other ports serve protocols like DNS and SSH.

HTTP normally uses port 80. HTTPS uses port 443, SSH uses port 22, and DNS uses port 53. Knowing common ports is important for A+ networking questions.

DNS uses port 53 to resolve domain names into IP addresses. Port 25 is SMTP, 3389 is RDP, and 8080 is often used by web servers as an alternative to 80.

SSH uses port 22 for secure remote administration. HTTP uses 80, HTTPS uses 443, and POP3 commonly uses 110. These port numbers appear frequently on the A+ exam.

Ethernet cables use RJ45 connectors with eight pins. RJ11 is used by telephone lines, USB-C is for data and power, and VGA is for analog video.

Cat5e and most twisted-pair Ethernet standards support a maximum segment length of about 100 meters. Beyond that distance, signal loss becomes too high without a switch or repeater.

802.11ac, also called Wi-Fi 5, commonly uses the 5 GHz band for higher throughput. 802.11b and 802.11g use 2.4 GHz. Bluetooth is a different wireless technology.

An IP address identifies a device on a network so data can be routed to it. It is not a hardware model, power rating, or file format.

A subnet mask defines which part of an IP address identifies the network and which part identifies the host. It is used to divide networks and determine routing boundaries.

This statement is true. DHCP automatically assigns IP addresses, subnet masks, gateways, and DNS settings to clients. It reduces manual configuration errors on a network.

DNS translates human-readable domain names into IP addresses. DHCP assigns addresses, antivirus software blocks malware, and encryption protects data in transit.

This statement is false. A switch forwards frames within the same local network. A router connects different networks and routes traffic between them.

A router connects different networks and makes routing decisions based on IP addresses. A switch connects devices on the same LAN, and a hub simply repeats signals.

A switch forwards Ethernet frames between devices on the same local network. A router connects networks, and a modem connects the local network to the ISP.

A default gateway is the router that devices use when sending traffic outside their local network. DNS, power backups, and email proxies serve different functions.

This statement is true. WPA3 improves security over WPA2 with stronger encryption and better protection against offline password guessing. It is the newer Wi-Fi security standard.

SSID stands for Service Set Identifier, which is the name of a wireless network. The other options are not real networking terms.

The ping command sends ICMP echo requests to test connectivity and measure response time. Format, copy, and tasklist are used for disks, files, and processes.

This statement is true. Lithium-ion batteries are lightweight and rechargeable, which makes them the common choice for smartphones and laptops.

A mobile hotspot shares a phone or tablet cellular data connection so other devices can access the internet. It does not expand storage, clean screens, or replace batteries.

Modern Android phones commonly use USB-C for charging and data transfer. VGA, RJ45, and HDMI are used for video and networking, not phone charging.

Synchronization keeps contacts, calendars, files, and settings consistent across devices and cloud services. It does not change battery capacity or cooling.

A docking station gives a laptop additional ports such as video, USB, Ethernet, and power. It does not physically upgrade RAM, CPU, or battery.

A hypervisor creates and manages virtual machines on a host system. It allocates CPU, memory, storage, and network resources to each VM.

A virtual machine is a software-based computer that runs on a physical host using a hypervisor. It has virtual hardware but behaves like a real computer.

IaaS provides virtualized hardware such as servers, storage, and networking. SaaS provides software over the internet, while PaaS provides a platform for developers.

SaaS delivers complete applications over the internet, such as email or office suites. IaaS provides infrastructure, and PaaS provides development platforms.

The host is the physical computer that runs the hypervisor and virtual machines. The guest is the virtual machine running an operating system.

Virtualization improves resource utilization by running multiple workloads on fewer physical machines. It does not remove storage needs or provide unlimited resources.

VDI stands for Virtual Desktop Infrastructure, which hosts desktops on central servers and delivers them to user devices. The other options are not real terms.

Cloud computing uses remote servers and services accessed over the internet. Local storage and direct cable connections are not cloud computing.

Beep codes often indicate RAM or video problems. Reseating RAM and checking the video cable are safe first steps. Keyboard, antivirus, and wallpaper do not cause POST video failures.

Power settings and background applications have a large effect on battery life. Screen, font, and Wi-Fi name changes do not explain fast battery drain.

A missing link light usually means a bad cable, disabled port, or powered-down device. Checking these is the correct troubleshooting step before deeper network tests.

The correct response is to clear the jam using the printer instructions. Toner, cables, and computer reboots do not remove a paper jam.

No Signal usually means the display is not receiving video from the computer. Check the cable and the monitor input source before investigating other components.

Adding RAM or replacing a hard drive with an SSD gives the largest practical speed improvement for most systems. Wallpaper, cables, and extra monitors do not improve performance.

The most common Wi-Fi connection issues are disabled radios, wrong passwords, or wrong networks. Battery, brightness, and storage do not prevent Wi-Fi authentication.

Clicking sounds often indicate mechanical failure. Protect your data by backing it up and replace the failing drive as soon as possible.

An ESD strap safely grounds a technician and prevents electrostatic discharge damage. Multimeters test voltage, cable testers check cabling, and loopback plugs test ports.