Free CompTIA Study Resources — A+, Network+, Security+

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100 free guides covering everything tested on CompTIA A+, Network+, and Security+ — from OSI model basics to Active Directory, routing protocols, and social engineering attacks. Written to actually explain the concepts, not just list facts to memorize.

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100 Articles
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Exam Coverage
A+, Network+, Security+
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Pick your cert and follow the path. The Networking Roadmap takes you from zero to Network+ in the right order — every topic sequenced so you're never studying something before you have the foundation for it. Already know what you need? Jump straight to a cheat sheet.

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All Guides

100 guides
📐 Core Concepts
CompTIA A+ · 220-1201 & 220-1202

CompTIA A+ Cheat Sheet 2026

Every port, connector type, RAM, storage interface, wireless standard, Windows command, security threat, troubleshooting methodology, and key acronym for the 220-1201 and 220-1202 exams — on one page.

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Exam Prep

Best CompTIA A+ Study Resources

The study guide, practice exams, and free resources worth your time — with prices, honest pros/cons, and who each is best for.

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Exam Prep

Best CompTIA Network+ Study Resources

Network+ is harder than A+ and worth more on a resume. Here's the Sybex study guide (with 10% exam voucher), Dion practice exams, and Professor Messer's free course.

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Exam Prep

Best CompTIA Security+ Study Resources

Security+ is the most recognized entry-level cybersecurity certification. Here's the Chapple & Seidl Sybex kit, Dion practice exams, and Professor Messer's free SY0-701 course.

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Security+

What is Cryptography?

Symmetric vs asymmetric encryption, hashing, PKI, digital signatures, and every cryptography concept tested on CompTIA Security+ SY0-701 — explained clearly with exam scenarios.

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Security+ · Network+

Encryption Types — Symmetric, Asymmetric, Hashing & Hybrid

AES, RSA, ECC, DES, SHA, MD5, Diffie-Hellman, HMAC — every algorithm tested on CompTIA Security+ with key distinctions, status (current/broken/deprecated), and 6 exam scenarios.

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A+ · Network+ · Security+

Cloud Computing Concepts — IaaS, PaaS, SaaS & Shared Responsibility

The three cloud service models, deployment types (public/private/hybrid/community), the shared responsibility model, CASB, shadow IT, and 6 exam scenarios tested across all three CompTIA exams.

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Security+

Zero Trust Security Explained

Never trust, always verify — Zero Trust is explicitly named in SY0-701. Covers the three core principles, five pillars, microsegmentation, ZTNA, JIT access, PDP/PEP, and 6 exam scenarios.

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Network+ · Security+

Network Segmentation — VLANs, DMZ, Microsegmentation

VLANs, screened subnets (DMZ), subnetting, air gaps, microsegmentation, and jump servers — how dividing a network into zones limits attack spread. Covers east-west vs north-south traffic, VLAN hopping, and 6 exam scenarios for Network+ and Security+.

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Security+

Physical Security Controls — Mantraps, Badges, Cameras & Secure Disposal

Access control vestibules, badge readers, biometrics (FAR/FRR/CER), CCTV, bollards, degaussing, shredding, and cryptographic erase — all physical security controls tested on Security+ SY0-701.

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Security+

Common Network Attacks Explained

Phishing, man-in-the-middle, DoS, DDoS, SQL injection, social engineering, and malware types — every attack tested on CompTIA Security+ and A+ with exam scenarios.

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Network+ · Security+

What is a VPN?

How VPNs work, tunneling protocols (IPsec, OpenVPN, PPTP), VPN types, split tunneling, and every VPN concept tested on CompTIA Network+ and Security+.

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Career

CompTIA A+ vs Network+ — Which Should You Take First?

What's the difference, which is harder, which pays more, and exactly which certification you should tackle first based on where you are right now.

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Career

Network+ vs Security+ — Which Should You Take Next?

Networking track or cybersecurity track? Which is harder, which pays more, and which certification makes sense based on where you want your IT career to go.

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Career

CompTIA CySA+ Explained — The Cybersecurity Analyst Cert After Security+

What CySA+ covers, who it's for, exam details, salary impact, and how it fits into the CompTIA cybersecurity path after Security+.

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Career

CompTIA CASP+ Explained — Advanced Security Practitioner Cert

What CASP+ covers, how it compares to CISSP, who should pursue it, and where it fits in the CompTIA advanced security certification path.

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CompTIA Network+

How to Pass CompTIA Network+ in 2026

A realistic study plan for N10-009, the subnetting strategy most candidates get wrong, domain breakdowns, and exam day tips that actually make a difference.

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CompTIA Network+

VLANs Explained — What is a VLAN?

What a VLAN is, how 802.1Q tagging works, trunk vs access ports, inter-VLAN routing (router on a stick vs Layer 3 switch), and every VLAN concept tested on Network+.

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CompTIA A+ · Network+

What is a Router? How Routers Work

Routing tables, default gateways, static vs dynamic routing, NAT, longest prefix match, and every router concept tested on CompTIA A+ and Network+ — explained clearly.

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CompTIA A+ · Network+

What is a Network Switch? How Switches Work

MAC address tables, VLANs, managed vs unmanaged, STP, port security, and every switch concept tested on CompTIA A+ and Network+ — explained clearly.

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CompTIA Network+

CompTIA Network+ Cheat Sheet 2026

Every port number, OSI model layer, subnetting reference, routing protocol, wireless standard, troubleshooting command, and key acronym for the N10-009 exam — all in one page.

View Cheat Sheet →
CompTIA Security+

How to Pass CompTIA Security+ in 2026

A realistic study plan for SY0-701, why scenario thinking matters more than memorisation, domain breakdowns, and the governance content most candidates skip and fail on.

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CompTIA A+

CompTIA A+ Complete Study Guide

Everything you need to pass 220-1201 and 220-1202 — both exam domain breakdowns, a 9-week study plan, the three highest-ROI topics, and links to every A+ concept on IT Study Hub organised by domain.

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Security+

Cloud Security Explained — CASB, CSPM & Misconfigurations

Security+ SY0-701 Domain 3 cloud security — shared responsibility model, CASB vs CSPM vs CWPP vs SASE, top cloud misconfigurations, serverless security, and container security with exam scenarios.

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CompTIA A+

How to Pass CompTIA A+ in 2026

A realistic study plan, what the exam actually tests across Core 1 and Core 2, how long to study, and exam day strategies that make a real difference.

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Security+

Identity and Access Management (IAM) Explained

MFA, SSO, Zero Trust, LDAP, PAM, and access control models — every IAM concept tested on CompTIA Security+ SY0-701, with exam scenarios.

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Active Directory · A+

Group Policy Objects (GPOs) Explained

GPO creation, LSDOU processing order (Local → Site → Domain → OU), inheritance, Block Inheritance vs Enforcement, security filtering, common security policies (password, BitLocker, AppLocker), and the gpupdate/gpresult commands.

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A+ · Network+ · Security+

CompTIA Port Numbers — Complete Reference

Every port tested on A+, Network+, and Security+ — FTP (20/21), SSH (22), DNS (53), HTTP/S (80/443), RDP (3389), LDAP/S (389/636), SNMP (161), and more. TCP vs UDP, encrypted vs unencrypted pairs, and the three biggest port exam traps.

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Security+

Incident Response Playbooks

Step-by-step IR playbooks for ransomware, data breach, DDoS, and phishing — mapped to PICERL phases. Covers containment strategies, order of volatility, notification sequencing, and the most tested IR scenario questions on Security+ SY0-701.

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Network+

CompTIA Network+ Complete Study Guide

Everything you need to pass Network+ N10-009 — exam structure, all 5 domain weightings, an 8-week study plan, the three highest-ROI topics, performance-based question formats, and links to every Network+ concept on IT Study Hub.

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Network+ · A+

Subnetting Guide — Magic Number Method & VLSM

The fastest subnetting method for exam conditions — magic number technique, every CIDR from /24 to /30, VLSM for variable-size subnets, four step-by-step worked examples, and three full PBQ-style practice scenarios for Network+ N10-009.

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Security+

CompTIA Security+ Complete Study Guide

Everything you need to pass Security+ SY0-701 — all 5 domain weightings, a 10-week study plan, the three highest-ROI topics, PBQ format guide, and links to every Security+ concept on IT Study Hub organised by domain.

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A+ · Network+ · Security+

Wireless Networking Explained

802.11 standards through Wi-Fi 6E, WPA3, site surveys (passive vs active vs predictive), RSSI and SNR metrics, EAP types for 802.1X (EAP-TLS, PEAP, EAP-FAST), antenna types, and the wireless troubleshooting methodology the exam puts in scenario questions.

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Core Model

OSI Model Explained (All 7 Layers)

The single most tested networking concept across A+, Network+, and Security+. Learn which protocols live at which layer, the memory tricks that actually stick, and how to use the OSI model to diagnose network problems the way the exam expects.

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Protocols

TCP vs UDP Explained

Why TCP uses a three-way handshake and UDP doesn't, which applications use each, the flags the exam tests (SYN, ACK, FIN, RST), and the security implications both protocols carry on Security+.

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Core Concept

What Is a MAC Address?

Every network device has a hardware address burned in at the factory. Learn how MACs differ from IPs, how switches use them, and how ARP connects the two.

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Ports & Services

Port Numbers — Complete Guide

Every port tested on A+, Network+, and Security+ — from the basics (80, 443, 22, 53) through Network+ infrastructure ports (BGP 179, RADIUS 1812, SIP 5060) and Security+ attack-surface ports (RDP 3389, SMB 445, Kerberos 88) — with exam scenarios for each.

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🌐 IP Addressing & Configuration
IP Addressing

What Is a Subnet Mask?

How subnet masks decide whether traffic stays local or goes to the router, the CIDR notation the exam uses constantly, and the segmentation scenarios that appear on both A+ and Network+.

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IP Addressing

Subnetting Explained

How to calculate network addresses, host ranges, and broadcast addresses. CIDR notation, worked examples, and every scenario tested on A+ and Network+.

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Core Concept

What Is DHCP?

The DORA process (Discover, Offer, Request, Acknowledge), lease times, APIPA fallback, DHCP relay agents, and what 169.254.x.x actually tells you when you're troubleshooting a connectivity problem.

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DNS

What Is DNS?

How DNS resolves names to IPs, the record types the exam tests (A, AAAA, MX, CNAME, PTR, NS), what breaks when DNS fails (IP works but names don't), and the DNS attacks — spoofing, poisoning, and hijacking — on Security+. Troubleshoot with nslookup and dig.

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Troubleshooting

What Is APIPA?

Why Windows assigns 169.254.x.x when DHCP fails, how to immediately recognise it as a DHCP problem, and the exact troubleshooting steps (ipconfig /release and /renew) the A+ exam expects when a user reports "no internet after moving to a new office."

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IP Addressing

IPv4 vs IPv6 Explained

Why IPv6 was created, how 128-bit addresses work vs 32-bit, the special address types the exam tests (link-local, loopback, multicast, global unicast), transition mechanisms (dual-stack, tunneling, NAT64), and the A+/Network+ scenarios you'll see.

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🔀 Traffic Flow & Routing
Core Concept

What Is a Default Gateway?

How the default gateway determines where traffic goes when the destination isn't on the local network, why "can ping 192.168.1.1 but not 8.8.8.8" points straight to a gateway problem, and how routing tables use it on Network+.

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Networking

What Is NAT?

How NAT maps thousands of private devices to a single public IP, the difference between static NAT, dynamic NAT, and PAT (the one your home router uses), and why NAT exists — and what breaks when it's misconfigured on the Network+ exam.

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Networking Hardware

Router vs Switch — What's the Difference?

Routers forward packets using IP addresses at Layer 3; switches forward frames using MAC addresses at Layer 2. When to use each, how MAC address tables are built, how routing tables differ, and the Layer 3 switch scenario that trips up most Network+ candidates.

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🔒 Troubleshooting & Security
Troubleshooting

Network Troubleshooting Commands

Windows commands (ipconfig, ping, tracert, nslookup, netstat) plus Linux equivalents (ip addr, dig, ss, tcpdump, nmap) — with a step-by-step diagnostic workflow and the A+/Network+/Security+ scenarios each command appears in.

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Network Security

Firewall Basics Explained

How firewall rules work (allow/deny, implicit deny at the end of every rule list), stateful vs stateless inspection, host-based vs network-based, Windows Defender Firewall profiles, and the ACL scenarios that appear on Network+ and Security+.

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🧰 Home Lab
Home Lab

Build Your First IT Home Lab on a Budget

You don't need expensive hardware. Start with two laptops and free VMs — how to build a realistic Windows Server lab for practicing A+, Network+, and Security+ scenarios including Active Directory, Group Policy, DNS, and RDP.

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Ready to sit the exam?

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Editor's Picks

Recommended Study Resources

Pair these with the guides on this site for the best chance at passing your exam on the first try.

Editor's Picks
🧪 Free Practice Exams 📖 CompTIA A+ Study Guide 📖 CompTIA Network+ Study Guide
🧰 New Section
Build Your IT Home Lab
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Networking Fundamentals

34 guides
Exam Structure · A+

CompTIA A+ Exam Domains (220-1201 & 220-1202)

All 9 domains across both A+ exams — Hardware & Network Troubleshooting (29%), Operating Systems (30%), Hardware (25%), Security (27%), and more. Exact weightings, what's tested in each domain, and study time allocation for Core 1 and Core 2.

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Operating Systems · A+

Windows 10 vs Windows 11 — A+ 220-1202

System requirements, TPM 2.0, Secure Boot, edition differences, upgrade path, and end-of-life dates. The key facts the CompTIA A+ 220-1202 Operating Systems domain tests about the differences between Windows 10 and Windows 11.

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Exam Structure · Network+

CompTIA Network+ Exam Domains (N10-009)

All 5 N10-009 domains with exact weightings — Networking Fundamentals (23%), Implementations (21%), Operations (19%), Security (19%), Troubleshooting (18%). What's actually tested in each domain and how to prioritise your study time.

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Exam Structure · Security+

CompTIA Security+ Exam Domains (SY0-701)

All 5 SY0-701 domains with weightings — Security Operations is the biggest at 28%. What each domain covers, which topics appear most on exam day, how SY0-701 differs from the previous version, and study time allocation.

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Exam Prep

Preparing for A+? See the Best Study Resources

The study guide, practice exams, and free video course worth your time — with prices, honest pros and cons, and a clear recommendation based on your budget and learning style.

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Protocols

TCP vs UDP Explained

Why TCP uses a three-way handshake and UDP doesn't, which protocols use each, the flags the exam tests (SYN, ACK, FIN, RST), and the security implications on Security+.

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Core Concept

OSI Model Explained (All 7 Layers)

The most tested networking concept across A+, N+, and Security+. Which protocols live at each layer, memory tricks, and how to use OSI to diagnose problems the way the exam expects.

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Core Concept · A+ & Network+

TCP/IP Model Explained — 4 Layers & Protocols

The 4-layer TCP/IP model that the internet actually runs on — Application, Transport, Internet, Network Access. How it maps to OSI, which protocols live at each layer, encapsulation from app to wire, TCP vs UDP, and exam scenarios.

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Core Concept · A+ & Network+

IP Address Classes — A, B, C, D, E + Private Ranges

Class A (1–126), B (128–191), C (192–223), D (multicast), E (reserved) — with host counts, default subnet masks, and the three RFC 1918 private ranges. Plus loopback (127.0.0.1), APIPA (169.254.x.x), and six exam scenarios.

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Master Guide

Networking Master Guide

The hub for all networking content — 40+ articles organized by topic so you can follow a logical path from OSI model basics through routing protocols, VLANs, wireless, VPNs, and security. Start here if you're not sure where to go next.

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Ports & Services

Common Port Numbers for the CompTIA A+ Exam

Ports 80, 443, 22, 53, 3389 (A+) through RADIUS 1812, BGP 179, SIP 5060 (Network+) through Kerberos 88, SMB 445, and RDP attack scenarios (Security+) — with memory tricks and exam scenarios for each.

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IP Addressing

What Is a Subnet Mask?

How masks determine local vs routed traffic, CIDR notation, and the segmentation scenarios that appear on both A+ and Network+.

Read Guide →
Troubleshooting

What Is APIPA?

Why Windows self-assigns 169.254.x.x when DHCP fails, how to spot it immediately, and the exact troubleshooting steps (ipconfig /release, /renew) the A+ exam expects.

Read Guide →
Core Concept

What Is DHCP?

The DORA handshake, lease times, DHCP relay for cross-subnet delivery, and what APIPA (169.254.x.x) tells you when DHCP fails — all tested on A+ and Network+.

Read Guide →
DNS

What Is DNS? (Domain Name System Explained Simply)

How DNS resolves names to IPs, record types (A, AAAA, MX, CNAME, PTR), what "IP works but names don't" tells you, and DNS attacks (spoofing, poisoning) on Security+.

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Core Concept

What Is a Default Gateway?

How the gateway handles traffic to remote networks, why "can ping 192.168.1.1 but not 8.8.8.8" points to a gateway problem, and how routing tables use it on Network+.

Read Guide →
Network Security

Firewall Basics Explained

Allow/deny rules, implicit deny, stateful vs stateless, and Windows Defender Firewall profiles — everything the A+ exam tests.

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Networking Hardware

Router vs Switch — What's the Difference?

Layer 3 routing on IP vs Layer 2 switching on MAC — when to use each, how MAC address tables are built, and the Layer 3 switch question that trips up most Network+ candidates.

Read Guide →
IP Addressing

IPv4 vs IPv6 Explained

Why IPv6 exists, how addresses differ, and the special addresses both exam versions test — including loopback, APIPA, and link-local.

Read Guide →
Core Concept

What Is a MAC Address?

Every network device has a permanent hardware address burned in at the factory. Learn how MACs differ from IPs, how switches use them, and how ARP connects the two.

Read Guide →
Home Lab

Build Your First IT Home Lab on a Budget

Start with two laptops and free VMs. A step-by-step guide to building a Windows Server lab for hands-on A+, Network+, and Security+ practice.

Read Guide →
Troubleshooting

Network Troubleshooting Commands (ipconfig, ping, tracert & more)

Master the six commands every IT technician uses daily — with real output examples and a step-by-step diagnostic workflow.

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Commands · A+ · Network+ · Security+

Linux Commands for CompTIA A+, Network+ & Security+

Every Linux command tested across all three CompTIA exams — ls, chmod, grep, ps, ifconfig, netstat, sudo, find, apt, and more. With syntax, key flags, and 7 exam scenarios covering permission, process, and networking questions.

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Linux · A+

Linux File System — Directory Structure, Permissions & File Types

Linux directory tree (/etc, /var, /home, /bin, /tmp, /boot), file system types (ext4, FAT32, exFAT, XFS), chmod permission values (755, 644), inodes, and mount points. Everything tested on CompTIA A+ 220-1202.

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Networking

What Is NAT? (Network Address Translation)

Static NAT, dynamic NAT, and PAT — how your home router maps thousands of devices to one public IP, and what breaks when NAT is misconfigured on the Network+ exam.

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Networking

WiFi Standards — 802.11 a/b/g/n/ac/ax Explained

📶 Every 802.11 standard tested on A+ and Network+ — speeds, frequency bands, channels, security protocols, and site survey concepts.

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Hardware

RAID Levels — 0, 1, 5, 6, and 10 Explained

💾 Minimum disks, fault tolerance, usable capacity, and use cases for every RAID level on the CompTIA A+ Core 1 exam.

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Networking

Network Topologies — Star, Bus, Ring, Mesh

🔗 Physical and logical network topologies for CompTIA A+ and Network+ — advantages, disadvantages, failure modes, and exam scenarios.

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Security

IDS vs IPS — Intrusion Detection vs Prevention

🛡️ How IDS and IPS work, where they sit in the network, detection methods, and how the exam distinguishes the two systems.

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Security

SIEM Explained — Log Aggregation and Correlation

📊 How SIEM collects, normalises, and correlates logs from all sources — the central tool of Security Operations for SY0-701 Domain 4.

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Security

Business Continuity — BCP, DRP, RTO, RPO

🔄 BCP vs DRP, RTO vs RPO, backup types, recovery site types, and the 3-2-1 backup rule for CompTIA Security+ and Network+.

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Security

Vulnerability Scanning — CVE, CVSS, and Tools

🔍 How vulnerability scanning works, CVSS severity scores, credentialed vs non-credentialed scans, and scanning vs pen testing.

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Security

Penetration Testing — Phases, Types, Rules of Engagement

⚔️ The five pen test phases, black/white/grey box testing, rules of engagement, OSINT, and post-exploitation concepts for Security+.

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Networking

Hub vs Switch vs Router Explained

Connects devices at Layers 1–3 — how hubs flood, how switches build MAC tables, how routers separate broadcast domains, and when each is the right device for the job.

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Windows / A+

Windows Registry — Hives, Keys & regedit

The five registry hives (HKLM, HKCU, HKCR, HKU, HKCC), regedit navigation, Run key malware persistence, and common registry troubleshooting for A+ Core 2.

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Security

Authentication Protocols — Kerberos, NTLM, RADIUS, LDAP

How Kerberos tickets work, NTLM challenge-response, RADIUS for 802.1X wireless, TACACS+ for device administration, and LDAP directory queries — tested across all three exams.

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Security

Firewall Types — Packet Filtering, Stateful, NGFW, WAF

The four firewall generations — stateless packet filtering, stateful inspection, next-generation application-aware firewalls, and WAFs that stop SQL injection and XSS.

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Security

Symmetric vs Asymmetric Encryption — AES vs RSA

How symmetric (AES, 3DES) and asymmetric (RSA, ECC) encryption work, the hybrid encryption model used by TLS, digital signatures, and hashing for Security+.

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Networking

TCP vs UDP — Connection-Oriented vs Connectionless

The three-way handshake, reliable delivery vs speed trade-off, which protocols use TCP vs UDP, SYN flood attacks, and the port numbers that show up on every CompTIA exam.

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Mobile / A+

Mobile Device Management — MDM, MAM & BYOD

MDM vs MAM, BYOD vs COPE vs CYOD, containerisation, remote wipe, compliance policies, and geofencing for CompTIA A+ Core 2 and Security+.

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Network+

Spanning Tree Protocol — STP, RSTP & Root Bridge

How STP prevents Layer 2 broadcast storms, root bridge election by Bridge ID, port roles and states, RSTP 1-second convergence, PortFast, and BPDU Guard for Network+.

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Cloud

Cloud Deployment Models — Public, Private, Hybrid

Public vs private vs hybrid vs community cloud, the shared responsibility model, cloud bursting, and how each deployment model appears on A+, Network+, and Security+.

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Security

Honeypots & Deception Technology Explained

How honeypots attract and trap attackers, low vs high interaction types, honeynets, canary tokens, and how deception technology appears on Security+ SY0-701.

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Security

Data Loss Prevention (DLP) Explained

Endpoint DLP, network DLP, and cloud DLP — how content inspection identifies sensitive data, data classification, regulatory drivers, and exam scenarios for Security+ Domain 3.

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Networking

OSI Model Cheat Sheet — All 7 Layers

All 7 OSI layers with protocols, devices, PDU names, encapsulation, mnemonics, and the top troubleshooting scenarios — the most tested networking concept on all three CompTIA exams.

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Networking

Hub vs Switch vs Router — What's the Difference?

🔀 OSI layers, collision domains, broadcast domains, MAC tables — the three most fundamental networking devices for A+ and Network+.

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A+ Core 2

Windows Registry — Hives, Keys, and regedit

🗂️ Five root hives, key startup paths, data types, regedit navigation, and malware persistence locations for CompTIA A+ Core 2.

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Security

Authentication Protocols — Kerberos, NTLM, RADIUS, TACACS+

🔑 Every authentication protocol across A+, Network+, and Security+ — ports, use cases, security properties, and exam scenarios.

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Security

Firewall Types — Packet Filter, Stateful, NGFW, WAF

🔥 Which firewall type to choose for any scenario — OSI layers, capabilities, DPI, WAF for OWASP Top 10, and implicit deny.

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Networking

Spanning Tree Protocol — STP, RSTP, Root Bridge

🌳 How STP prevents broadcast storms, root bridge election, port states, RSTP convergence, PortFast, and BPDU Guard.

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Security

Mobile Device Management — MDM, MAM, BYOD

📱 MDM vs MAM, BYOD vs COPE, remote wipe, geofencing, containerisation, and mobile security for A+ and Security+.

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Security

Honeypots — Deception Technology for CompTIA Security+

🍯 Honeypots, honeynets, honeyfiles, and canary tokens — low vs high interaction, detection use cases, and Security+ exam scenarios.

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Security

Data Loss Prevention — Endpoint, Network, Cloud DLP

🔐 How DLP identifies and blocks sensitive data transfers — endpoint vs network vs cloud, data classification, and compliance.

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Cloud

Cloud Deployment Models — Public, Private, Hybrid, Community

☁️ Trade-offs between all four cloud deployment models, shared responsibility, IaaS/PaaS/SaaS, and exam scenarios.

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Security

Symmetric vs Asymmetric Encryption — AES, RSA, ECC

🔒 AES vs RSA vs ECC, key lengths, digital signatures, hybrid encryption, TLS, and perfect forward secrecy for Security+.

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Networking

TCP vs UDP — Connection-Oriented vs Connectionless

📡 3-way handshake, SYN flood attack, which protocols use TCP vs UDP, QoS, and netstat — for A+ and Network+.

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Networking

OSI Model Cheat Sheet — All 7 Layers with Devices and Protocols

📋 Every OSI layer with PDUs, devices, protocols, mnemonics, and the bottom-up troubleshooting approach for all three exams.

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