CompTIA Network+ 10e - Quick Study Guide
Original 2-page study sheet for networking fundamentals. Use it with your official textbook, MindTap assignments, labs, quizzes, and
instructor materials.
Exam mindset: understand what each device/protocol does, where it lives in the network, what breaks when it fails, and what command
proves it.
Concept
Know this cold
OSI / TCP/IP models
OSI layers 1-7: Physical, Data Link, Network, Transport, Session, Presentation, Application. TCP/IP maps roughly to Link, Internet,
Transport, Application. Use models to isolate problems instead of randomly clicking like a raccoon with a keyboard.
Ethernet & switching
Switches forward frames using MAC addresses. VLANs segment Layer 2 networks. Trunks carry multiple VLANs. STP prevents switching
loops. Full-duplex avoids collisions; half-duplex is mostly fossil fuel.
IP addressing
IPv4 uses 32-bit addresses with subnet masks/CIDR. Know network ID, host range, broadcast address, default gateway, private ranges,
APIPA 169.254.0.0/16, and why DNS is not the same thing as DHCP.
Routing
Routers move packets between networks using routing tables. Static routes are manual. Dynamic routing uses protocols like OSPF,
EIGRP, BGP, and RIP. Default route is the catch-all path, usually 0.0.0.0/0.
Transport layer
TCP is connection-oriented, reliable, and uses acknowledgments. UDP is faster and connectionless. Common test clue: if reliability/order
matters, TCP; if speed/low overhead matters, UDP.
Core services and ports
Service
Port(s)
Purpose
FTP / SFTP
20,21 / 22
File transfer. SFTP rides over SSH; FTP is not secure.
SSH / Telnet
22 / 23
Remote CLI. SSH good. Telnet bad unless you enjoy leaking credentials.
SMTP / POP3 / IMAP
25,110,143,
587/993/995
Email send/retrieve. Secure variants commonly use TLS.
DNS / DHCP
53 / 67,68
Name resolution / automatic IP configuration.
HTTP / HTTPS
80 / 443
Web traffic. HTTPS uses TLS.
SNMP / RDP / SMB
161,162 / 3389 / 445
Monitoring, remote desktop, Windows file sharing.
Subnetting quick pass
• CIDR: /24 means 24 network bits and 8 host bits. Usable hosts = 2^host bits - 2, except special cases like /31 point-to-point links.
• Common masks: /24 = 255.255.255.0, /25 = 126 hosts, /26 = 62 hosts, /27 = 30 hosts, /28 = 14 hosts, /29 = 6 hosts, /30 = 2 hosts.
• Troubleshooting: wrong subnet mask or gateway can make local traffic work while internet/other-network traffic fails. That is not magic. That is
Layer 3 being petty.
Original quick study guide - CompTIA Network+ 10e / ITNW-1425 networking fundamentals
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CompTIA Network+ 10e - Troubleshooting & Exam Review
Use this page as the rapid review before labs, quizzes, and exams.
Wireless essentials
• 802.11 standards: know the pattern: newer standards usually mean better throughput, efficiency, and features. 2.4 GHz has range but more
interference; 5 GHz has speed and less range; 6 GHz adds cleaner spectrum for newer gear.
• Security: WPA2/WPA3 are normal modern answers. WEP is dead. Open Wi-Fi is not secure just because the coffee is expensive.
• Common problems: weak signal, channel overlap, interference, wrong SSID/passphrase, overloaded AP, bad placement, mismatched security
settings.
Network security basics
• AAA: Authentication proves identity, authorization controls access, accounting logs activity.
• Defense tools: firewalls filter traffic, IDS detects, IPS can block, VPN encrypts tunnels, NAC checks device compliance, ACLs permit/deny
traffic.
• Hardening: change defaults, patch firmware/software, disable unused ports/services, use least privilege, segment networks, back up configs,
log events.
• Threats: phishing, malware, rogue AP, evil twin, on-path attacks, DoS/DDoS, credential attacks, VLAN hopping, spoofing, social engineering.
Command-line troubleshooting
Command
Use it for
ipconfig / ifconfig / ip addr
Check IP address, subnet mask, gateway, DNS, interface state.
ping
Basic reachability test. Failure does not always mean host is down; ICMP may be blocked.
tracert / traceroute
Shows path/hops toward destination. Useful for routing/path problems.
nslookup / dig
Tests DNS records and name resolution.
netstat / ss
Shows active connections and listening ports.
arp -a
Displays IP-to-MAC mappings on local network.
route print / ip route
Shows routing table and default route.
tcpdump / Wireshark
Packet capture. The truth serum when the network is lying to you.
Seven-step troubleshooting process
• 1. Identify the problem: gather symptoms, ask what changed, duplicate the issue if safe.
• 2. Establish a theory: start with the obvious, then move layer-by-layer through OSI.
• 3. Test the theory: prove it instead of guessing. Guessing is how tickets become archaeology.
• 4. Create a plan and identify effects: avoid breaking ten users to fix one user.
• 5. Implement the fix or escalate with notes.
• 6. Verify full functionality and add preventive measures.
• 7. Document the issue, cause, fix, and final result.
Study plan for ITNW-1425 / Network+ style content
• Before reading: scan headings, objectives, diagrams, tables, and key terms. Do not start cold and hope your brain magically installs networking
drivers.
• During reading: build a table with term, definition, layer, command/port, and real-world use. Convert every protocol into a flashcard.
• After reading: do the lab first if available, then quiz yourself without notes. Missed questions become your actual study list.
• Weekly focus: 30 minutes ports/commands, 30 minutes subnetting, 30 minutes troubleshooting scenarios, then review Canvas/MindTap
deadlines.
Final check before quizzes/exams
• Can you explain the difference between switch, router, firewall, AP, modem, and gateway?
• Can you read an IP/mask and tell whether two hosts are on the same subnet?
• Can you match common services to ports without doom-scrolling a port chart?
• Can you troubleshoot from Physical Layer up instead of changing random settings like a caffeinated goblin?
Original quick study guide - CompTIA Network+ 10e / ITNW-1425 networking fundamentals
Page 2