CompTIA A+ 220-1101 Core 1 Personal Flashcards (Simplified & Concise Definitions)

Personal set where I edited several definitions to be more correct and concise. Also added some terms. Verify accurate definitions before use because the ones I didn't edit might still be inaccurate or too long.

Local Area Network (LAN)

A small network such as one building or floor
(1.1 & 2.7)

Inverters and Backlights

• All LCD displays have a backlight; OLED does not

• Many phones and laptops use LCD but are moving towards OLED

• Inverters are generally only used for fluorescent LCDs to convert DC to AC

Router Security Protocols

• WEP (Wired Equivalent Privacy) – Weak encryption, easily cracked, outdated

• WPA (Wi-Fi Protected Access) – Improved security over WEP, uses TKIP

• WPA2 – Stronger encryption (AES), widely used standard

• WPA3 – Latest security upgrade, better encryption & protection from brute force attacks

What is WPS (Wi-Fi Protected Setup)?

• Designed for easy Wi-Fi setup (push-button or PIN)

• Major security risk – vulnerable to brute-force attacks

• Best practice: Disable WPS to improve network security

Network Performance Metrics

• Jitter – Variability in packet delay; affects VoIP & video calls

• Latency – Time delay for data to travel; measured as round-trip time

• Throughput – Actual data transferred over time (real performance)

• Bandwidth – Maximum possible data transfer rate (theoretical)

NAS (Network-Attached Storage)

A dedicated file storage device connected to a network, allowing multiple users/devices to access and share files remotely or locally over the network.

Printer Spooler

• A background service that manages print jobs in a queue before sending them to the printer. Allows multiple users to print without waiting for jobs to finish one at a time.

• Restart of jobs get stuck

Common PSU Voltages (ATX)

• +12V → Fans, drives, CPUs, GPUs

• +5V → Some logic boards, older drives

• +3.3V → RAM, newer chips

Network Address Translation (NAT)

• Allows multiple devices on a private network to share a single public IP.

• Modifies IP addresses in packet headers as they pass through a router.

• Improves security by hiding internal IP addresses.

• Common in home and business networks.

KVM Switch (Keyboard Video Mouse)

• Allows user to control multiple computers from one or more sets of keyboards, video monitors, and mouse

• Typically used in server management to quickly between servers

Special IPv4 Addresses

• Multicast: 224.x.x.x - 239.x.x.x (one-to-many communication)

• Broadcast: 255.255.255.255 (sends to all devices on network)

Optical Disc Storage Sizes

• CD: 700 MB.

• DVD: 4.7 GB for single-layer disc & 8.5 GB for a dual-layer disc.

• Blu-ray: 25 GB for a single-layer disc & 50 GB for a dual-layer disc.

Switch

• Connects devices in a LAN and forwards data only to the intended recipient using MAC addresses

• Reduces congestion and collision compared to hubs, increasing speed

• Used in businesses and homes for wired networking

Unmanaged Switch

• Basic plug-and-play switch that forwards data using MAC addresses.

• No configuration, VLANs, or traffic management—just direct device connections.

• Cheaper and simpler than a managed switch, but lacks control features.

• Used in homes and small offices where advanced settings aren’t needed.

Boot Start-Up Keys

• Use F2, F12, or Delete to access BIOS

• F11 boots into recovery mode on Windows computers

• F8 used for Advanced Boot Options menu to allow the selection of different startup modes for troubleshooting

Transfer Roller

• Applies an electric charge to the paper to attract toner from the imaging drum

• Ensures toner transfers evenly before the fuser permanently bonds it

Pickup Roller

• Grabs paper from the tray and feeds it into the printer

• Worn-out rollers cause paper jams or failure to pick up paper

Duplexing Assembly

• Flips the paper inside the printer for double-sided printing

• Involves rollers and gears to reposition the paper automatically

Transfer Belt

• Used in color laser printers to move all colors (CMYK) of toner to paper in one pass

• More efficient than single-color transfer rollers

Imaging Drum

• Attracts toner, where the laser has discharged the charge, to form an image using electrostatic charges.

• Transfers toner to paper before it's fused (via transfer roller or belt).

• Often integrated into the toner cartridge in smaller printers.

Fuser Assembly

• Uses two rollers: a heated roller and a pressure roller

• Uses heat and pressure to permanently bond toner to paper

• Composed of a heated roller and a pressure roller

• If failing, prints may smudge or rub off

Toner Cartridge

• Contains toner (fine, dry, powdered ink) and sometimes the imaging drum

• Can be replaced when toner runs low

• If low or defective, prints may be faded or streaky

Primary Corona Wire / Charge Roller

• Applies initial charge to the imaging drum before laser exposure.

• Older models use a corona wire, newer ones use a charge roller.

• If faulty, prints may be blank or distorted due to improper charge.

Separation Pads

• Prevents multiple sheets from feeding into the printer at once.

• Works with the pickup roller to pull a single page.

Laser

• Creates the electrostatic image on the imaging drum.

• Determines the print resolution and sharpness.

Page Description Languages

• Define how printers should render documents on a page

• Examples include PCL, PostScript, IPP, and LPD

Printer Control Language (PCL)

• Faster but lower-quality print output

• Commonly used for general office printing

PostScript (PS)

• Slower but produces higher-quality output

• Often used in professional publishing and graphics

VM Sprawl

• Uncontrolled growth of VMs due to poor management

• Leads to security risks & resource drain

VM Escape

• Exploiting vulnerabilities to break out of a VM and access the host system

• Can allow attackers to control other VMs or the host itself

Rogue VM

• Unauthorized VM instances that pose security & compliance risks

• May bypass monitoring & create vulnerabilities

Data Remanence

• Residual data left on virtualized storage after VM deletion

• Risk of unauthorized access if not properly sanitized

• Encryption & secure wiping help mitigate threats

• Cloud environments & rapid elasticity increase risk

Bad or Faulty RAM Symptoms

• System reboots randomly

• Sluggish performance, especially in memory-heavy apps

• Slow loading of websites & programs

• Potential BSOD or crashes

• Use memory diagnostics to confirm

(5.2)

Steady NIC Indicator Lights

• Steady lights indicate no network activity.

• Blinking indicates that data is passing over the NIC to the network.

• Blinking lights, even if incorrect TCP/IP configuration or intermittent connectivity, indicates transmission attempts

(5.7)

HFC (Hybrid Fiber-Coaxial)

• Broadband internet using fiber & coaxial cables

• Fiber to neighborhood node, then coax to each home

• Cable Modem for internet access

• Uses DOCSIS standard (Data Over Cable Service Interface Specification)

• Speeds: 50 Mbps - 1 Gbps+

• Shared bandwidth → Performance can vary based on network congestion

OS not found

• Usually indicates corrupted/fault MBR (Master Boot Record) or GPT (Globally Unique ID Partition Table)

• To fix, reboot into the Windows recovery mode and use the 'bootrec /fixboot' command to fix the GPT

Port 427

• SLP (Service Location Protocol)

• Protocol for organizing and locating resources (e.g. printers, disk drives, databases, e-mail directories, and schedulers) in a network

• Alternative to LDAP

• Primary UDP but sometimes TCP

3G

• 2 Techs used: HSPA+ and EV-DO

• HSPA+ (Evolved High-Speed Packet Access) 3G standard used in GSM cellular networks

• EV-DO (Evolution-Data Optimized) 3G standard used for CDMA cellular networks

4G

• Uses LTE and LTE-A

• LTE: Packet-based upgrade for GSM & CDMA2000 networks

5G

• Made up of three different types: low-band, mid-band, and high-band mmWave technology.

Zigbee and Z-Wave

• Both wireless communication protocols used for home automation

• Zigbee is open-source; 2.4 GHz

• Z-Wave is proprietary

SSID (Service Set Identifier)

• It’s the name of a Wi-Fi network.

• It helps devices identify and connect to the correct wireless network.

• Can be broadcasted (visible) or hidden (manual entry required).

• Changing the default SSID enhances security but does not prevent attacks.

Bandwidth Saturation

• Bandwidth is the maximum data transfer rate of a network, measured in Mbps or Gbps.

• Bandwidth Saturation occurs when the network's full capacity is used, leading to slow speeds.

• Causes: High traffic, streaming, large downloads, too many devices.

• Solutions: QoS (Quality of Service), upgrading bandwidth, reducing unnecessary traffic.

Hub

• Simple, legacy networking device

  • Replaced by switches for better efficiency and security

• Connects multiple devices on a LAN

• Broadcasts all incoming data to every connected device/port

  • No traffic filtering or directing (unlike switch)

  • Causes network congestion

• Operates at Layer 1 (Physical Layer) of the OSI model

Laser Printer Power & DC Voltages

• Laser printers use a DC power supply (DCPS) to convert AC to DC.

• Common voltages:

  • +5 VDC & -5 VDC → Power the logic board.

  • +24 VDC → Powers motors for paper movement.

• Not used: -24 VDC (Not found in standard laser printers).

Laptop Terms

1. [External] Power Adapter

2. DC Jack

• Charger

• Laptop Charging Port (converts the AC power from the wall into DC power)

IaaS vs PaaS

• IaaS → Raw infrastructure (servers, storage, networking). Full control over OS, apps, and configs. Use case: Hosting custom apps while managing everything.

• PaaS → Managed platform (OS, runtime, databases). Focus on coding, not infrastructure. Use case: Developers deploying apps without server maintenance.

Thin Clients

Thin Client Basics:

• Thin Client → Lightweight computer relying on a remote server.

• VDI → Virtual desktops run on a central server, not locally.

• Benefits → Lower cost, easy management, better security.

Setup Steps:

1. Connect to Network (Ensure internet/LAN access).

2. Install VDI Client (Configure connection to VDI).

3. Set Up User Credentials (Login for virtual desktop access).

Hybrid vs Community Cloud

• Hybrid Cloud → Mix of on-premises and public cloud. Moves data/apps as needed. Example: Store sensitive data locally, use cloud for scalability.

• Community Cloud → Shared by organizations with similar needs (e.g., government, healthcare). Not for integrating on-prem with cloud.

Conflated Virtualization Terms

• Hypervisor → Software that runs VMs.

  • Type 1 (Bare-metal) → Runs directly on hardware. Faster.

  • Type 2 (Hosted) → Runs on a host OS. Slower.

• VT (Intel) / AMD-V → Hardware features for better virtualization.

• Not Virtualization:

  • HyperThreading (Intel) / SMT (AMD) → CPU tech for running multiple threads per core.

CDMA vs GSM

CDMA (Code Division Multiple Access):

• No SIM card (built-in carrier lock)

• Used mainly in the U.S. (Verizon, Sprint)

• Limited global compatibility

• Older technology

GSM (Global System for Mobile Communications):

• Uses SIM cards (easy device swapping)

• Global standard (AT&T, T-Mobile, most of the world)

• Better for international use

Key Difference:

• GSM = SIM flexibility

• CDMA = Carrier-locked

Note:

• Both are legacy technologies—replaced by 4G LTE and 5G, which support SIM-based, global communication.

Components of CDMA

• PRL (Preferred Roaming List) → Lists which towers to use when roaming (carrier-updated).

• PRI (Product Release Information → Stores network settings for carrier communication (carrier-updated).

• Baseband Updates → Firmware updates to Improve phone radio connectivity.

• IMSI (International Mobile Subscriber Identity) → Identifies a mobile user (common in GSM, relevant for LTE).

• ESN/MEID (Electronic Serial Number/Mobile Equipment Identifier) → Unique hardware ID for CDMA phones (no SIM card needed).

PRL (Preferred Roaming List)

Lists which towers to use when roaming for CDMA phones (carrier-updated).

PRI (Product Release Information)

• Stores network settings for carrier communication for CDMA phones (carrier-updated).

• Controls features like network access, data rates, etc.

  • Contains other important information that allows your phone to connect to the right mobile provider's network

Baseband Updates

Firmware updates for the phone’s radio to improve connectivity.

Subnet Mask

Divides IP address into two parts:

• Network ID (which network you're on)

• Host ID (specific devices on that network)

• Used by routers and devices to determine if a device is local or remote.

• Helps route packets within and between networks.

• Common subnet masks:

  • 255.255.255.0 → Class C (supports up to 254 hosts)

  • 255.255.0.0 → Class B

  • 255.0.0.0 → Class A

What should you do if the power supply’s fan is not working?

• If the fan in power supply is faulty, replace entire power supply

• Never attempt to repair or fix broken power supply or broken power supply cooling fan due to the power supply's high voltage electrical components.

• When a fan creates grinding sounds, this is evidence of impending failure and device needs to be replaced

127.0.0.1

• Localhost IP for testing your network interface card (NIC).

• Reserved for loopback test.

• No communication of the return packet indicates network card is faulty, the cable/loopback is loose, or bad wiring of loopback plug.

• Using ping with public IP addresses or the gateway address, such as 1.1.1.1, 8.8.8.8, and 192.168.1.1, would instead verify the entire path and not just NIC's driver.

CompTIA Troubeshooting Methodology

1. Identify the problem

2. Establish a theory of probable cause

3. Test the theory to determine the cause

4. Establish a plan of action & Implement the solution

5. Verify full system functionality & Implement Preventative Measures

6. Document findings, actions, outcomes

Hotspot

Phone acts as router to provide wireless connection to internet for other devices

• Creates wireless network multiple devices can connect to

• Allows multiple devices to access internet through phone

Tethering

Phone acts as modem to provide (often wired) connection to internet for other devices

• Can also use Bluetooth or WiFi for this, but WiFi is called hotspot

• Direct connection

• One device uses phone’s connection to access internet

• More secure than hotspot

Line Printer Daemon & Internet Printing Protocol

• IPP: Uses HTTP to communicate between clients and printers/print servers. Largely replaced LPD

• LPD: Older protocol for submitting print jobs to remote printers.

• Both uses for remote print jobs

VM Network Connection Types

• Localhost: The VM can only communicate with itself

• Private: VMs can only communicate with other VMs on same virtual network but not with the host or the internet (like a private club only for VMs on that network)

• Internal: The VM can communicate with the host and other VMs on the same virtual network (think of intranet, can talk to everyone, including the host, on that network)

• External: The VM can connect to the internet (and the external network like a LAN), the host, and other machines on the same network

2.4 GHz vs 5.0 GHz

• 5.0 GHz has more channels than 2.4 GHz, so less congestion and interference, allowing higher data rates

• 2.4 GHz has a longer wavelength making it better at propagating through solid surfaces while also giving it a longer range at the same power output levels

• 5 GHz is higher frequency than 2.4 GHz

• Means 5 GHz signals have shorter wavelengths and can transmit more data faster, but over a shorter range,

• 2.4 GHz signals have longer wavelengths and can travel further, but at slower speeds

NS (Nameserver)

Indicates which DNS server is authoritative for that domain

A Record (Address Record)

• Maps a domain name to its IPv4 address

AAAA (Quad A)

Used to map the IPV6 to its respective domain name

CNAME (Canonical Name)

Maps an alias name to a true domain name.

• These records are typically used to map a subdomain such as www or mail to the domain hosting that subdomain's content

TXT (Text Records)

Allows owner to insert text into DNS records, often for verification, policy info, or email security
(2.6)

Campus Area Network (CAN)

A computer network that connects two or more LANs that are located on a campus.

Personal Area Network (PAN)

- Provides communication for devices owned by a single user that work over a very short distance
- Bluetooth, IR, NFC, etc.
(1.1 & 2.7)

MAN (Metropolitan Area Network)

- A network covering a city
- Bigger than LAN, usually smaller than WAN
- Common to see government ownership
(2.7)

SAN (Storage Area Network)

Specialized, high-speed network that provides block-level network access to storage.
(2.7)

WLAN (Wireless Local Area Network)

A wireless local area network
(2.7)

USB 1.1

• 12 Mbps

• 2.5W

USB 2.0

• 480 Mbps (high speed)

• 2.5W

• 5 meters max length

USB 3.0

• 5 Gbps (superspeed)

• 4.5W

• 3 meters (No specified Length)

• Often blue or red

Port 69

• Used for Trivial File Transfer Protocol (TFTP)

• Lightweight Version of FTP

• Uses UDP

Port 137, 138, 139

• Used for NetBIOS services, including name resolution and file sharing.

• Allows computers to communicate with each other over a network

• Uses TCP protocol

• Facilitating communication and file sharing in Windows networks.

• Used before SMB

LCD (Liquid Crystal Display)

• Lightweight & Inexpensive

• Poor black levels due to separate Backlight

• Traditionally used fluorescent backlights, now uses LED backlight
  (1.2)

LED

An LCD display that uses an LED backlight instead of a fluorescent one

TN (twisted nematic)

Fast response Times - Low cost - Low Power Use - Limited Viewing Angles - Used in LCD displays
(1.2)

IPS (In Plane Switching)

Best Colors - Better Viewing Angles - More Expensive - Used in LCD displays
(1.2)

VA (Vertical Alignment)

Best Contrast - Slower response times than TN - Used in LCD displays

OLED (organic light-emitting diode)

Doesn't have backlight - Better Contrast than LCD - Does not use TN, IPS, or VA
(1.2)

Plasma

• Uses tiny gas-filled cells that create plasma when voltage is applied

• Plasma excites phosphors to produce light and color

• Deep blacks, high contrast, but largely replaced by LED/OLED

QLED

Quantum Light Emitting Diode - Type of LCD - Thousands of tiny LED backlights enhance color accuracy & brightness

MDM

Mobile device management: Allows company to manage employee devices
- Centralized management system
- Ensures device security
(1.4)

MAM

Mobile Application management:
- Set policies & restrictions on apps
- Control Company software (Update, Remove, Etc.)
(1.4)

UDP

User Datagram Protocol. A protocol used on the internet for fast transmission of information but with minimal error checking

• Connectionless protocol that allows data to be sent without establishing a connection, prioritizing speed over reliability.

TCP/IP

The very popular suite of network protocols that includes TCP, IP, UDP & dozens of other protocols
- These communication protocols allow devices to transfer data and communicate over the internet

TCP

Transmission Control Protocol

• Provides reliable, ordered, and error-checked delivery of a stream of packets on the internet.

• Guarantees packet delivery via use of virtual circuit and data acknowledgment

• Connection-oriented, so slower

• Verifies integrity of delivered packets

PRL (Preferred Roaming List)

- Allows phone to connect to the right tower
(1.4)

Port 20, 21

FTP (File Transfer Protocol)

• Used for transferring files from one host to another

• Uses TCP

• Insecure
  (2.1)

Port 22

SSH (Secure Shell) - TCP protocol

• Encrypted Communication

• Secure version of Telnet

• Allows remote access to computers, like telnet

• (2.1)

Secure File Transfer Protocol (SFTP) - TCP

• secure file transfer protocol. It runs over the SSH protocol. It supports the full security and authentication functionality of SSH.

Port 23

Telnet (Telecommunications Network) - TCP Protocol
- Non-encrypted remote control of computer
- Log into devices remotely
(2.1)

Port 25

SMTP (Simple Mail Transfer Protocol)
- TCP protocol
- Used to send email (outbound mail)
(2.1)

Port 53

DNS (Domain Name System)
- Uses both UDP and TCP Protocol, but moreso UDP
- Converts hostnames (URL addresses) to IP addresses
- CRITICAL Resource
(2.1)

Port 67, 68

DHCP (Dynamic Host Configuration Protocol)
- UDP Protocol
- Automated assignment & and configuration of IP addresses to devices
- IPs can be reserved for certain devices
- IP Range: 10.1.10.10 through 10.1.10.199
(2.1)

Port 80

HTTP (Hypertext Transfer Protocol)

• Uses TCP protocl

• Manages non-encrypted communication between web server and client in the browser
  (2.1)