CompTIA Network+ N10-009 Study Guide and Exam Tips

Network+ is the vendor-neutral networking certification. Cisco has CCNA, Juniper has JNCIA, but Network+ doesn't test you on any specific vendor's CLI or hardware. It tests whether you understand how networks actually work: protocols, topologies, troubleshooting methodology, and security concepts that apply regardless of what equipment you're configuring. That's why it transfers across employers and why the DoD accepts it for 8570 compliance.

The current version is the N10-009, launched in June 2024 and replacing the N10-008. It runs 90 questions in 90 minutes, with a passing score of 720 out of 900. The questions are a mix of multiple-choice and performance-based questions (PBQs), which are hands-on simulations where you configure, troubleshoot, or analyze a network scenario directly.

What Changed from N10-008 to N10-009

The N10-009 shifted weight toward troubleshooting and operations while pulling back slightly on security (since Security+ covers that in depth). The biggest content additions reflect how modern networks actually operate: more coverage of software-defined networking (SDN), SD-WAN for multi-site environments, Infrastructure as Code (IaC) for automated provisioning, and VxLAN for large-scale overlay networks. Physical network design also got expanded treatment, including MDF/IDF layout planning.

If you studied for the N10-008, the core material is still there. The exam just expects you to also understand how traditional networking concepts extend into cloud and software-defined environments. The N10-008 retired in November 2024, so the N10-009 is the only option now.

The Five Domains

Network+ splits into five weighted domains:

• Networking Concepts (23%) — OSI model, TCP/IP, ports and protocols, IP addressing, network topologies, cloud concepts
• Network Implementation (20%) — Routing, switching, wireless standards, WAN technologies, cabling
• Network Operations (19%) — Monitoring, documentation, disaster recovery, organizational policies, SNMP, syslog
• Network Security (14%) — Authentication, access control, common attacks, hardening techniques
• Network Troubleshooting (24%) — Troubleshooting methodology, wired/wireless issues, network service problems

Troubleshooting is the largest domain at 24%, and Networking Concepts is close behind at 23%. Together they account for nearly half the exam. Security is the smallest domain at 14%, which makes sense given CompTIA's expectation that you'll pursue Security+ separately.

Networking Concepts: The Foundation

The OSI Model

You need the seven layers memorized, along with what operates at each layer and the associated protocols. The exam doesn't ask you to recite them in order; it asks you to identify which layer is relevant to a given problem. If a user can ping an IP address but DNS resolution fails, that's a Layer 7 (Application) issue. If two switches can't communicate despite being physically connected, that's likely Layer 2 (Data Link).

The layers, from bottom to top:

1. Physical — Cables, connectors, hubs, electrical signals
2. Data Link — Switches, MAC addresses, ARP, VLANs, frames
3. Network — Routers, IP addresses, ICMP, subnetting, packets
4. Transport — TCP, UDP, port numbers, segments
5. Session — Session establishment and teardown
6. Presentation — Encryption, compression, data formatting
7. Application — HTTP, DNS, DHCP, FTP, SMTP, SNMP

Subnetting

Subnetting appears in multiple-choice questions and PBQs. You won't get a subnet calculator. You need to be able to determine the network address, broadcast address, valid host range, and number of usable hosts for a given CIDR notation by hand. A /24 gives you 254 hosts. A /25 gives you 126. A /26 gives you 62. You should be able to work these out in under 30 seconds each.

The fastest method for exam speed: know the powers of 2 for the host portion (2^n - 2 for usable hosts) and the corresponding subnet masks. For Class C subnetting, the magic numbers are 128, 64, 32, 16, 8, 4, 2, 1. Each represents the block size when you borrow bits. A /26 has a block size of 64, so the subnets start at .0, .64, .128, .192.

Ports and Protocols

You need to know the common port numbers cold. These come up in both multiple-choice and troubleshooting scenarios:

• 20/21 — FTP (data/control)
• 22 — SSH, SCP, SFTP
• 23 — Telnet
• 25 — SMTP
• 53 — DNS
• 67/68 — DHCP (server/client)
• 80 — HTTP
• 110 — POP3
• 143 — IMAP
• 443 — HTTPS
• 3389 — RDP
• 161/162 — SNMP (queries/traps)
• 389 — LDAP
• 636 — LDAPS

Network Implementation: Wireless and Routing

Wireless Standards

The 802.11 standards are tested by their characteristics, not just their names. Know the frequency bands, maximum throughput, and backward compatibility for each:

• 802.11a — 5 GHz, up to 54 Mbps
• 802.11b — 2.4 GHz, up to 11 Mbps
• 802.11g — 2.4 GHz, up to 54 Mbps
• 802.11n (Wi-Fi 4) — 2.4/5 GHz, up to 600 Mbps, MIMO
• 802.11ac (Wi-Fi 5) — 5 GHz, up to 6.9 Gbps, MU-MIMO
• 802.11ax (Wi-Fi 6/6E) — 2.4/5/6 GHz, up to 9.6 Gbps, OFDMA

The exam also tests wireless security protocols. WPA3 is the current standard, using SAE (Simultaneous Authentication of Equals) instead of the pre-shared key exchange that made WPA2 vulnerable to offline dictionary attacks. Know the progression: WEP (broken) to WPA (TKIP, deprecated) to WPA2 (AES/CCMP) to WPA3 (SAE).

Routing Protocols

You need to distinguish between distance-vector, link-state, and hybrid routing protocols. RIP uses hop count (max 15 hops). OSPF uses cost based on bandwidth and builds a complete topology map. EIGRP is Cisco-proprietary but tested on Network+ as a hybrid protocol. BGP is the protocol that routes between autonomous systems on the internet. The exam tests which protocol fits which scenario, not configuration syntax.

Performance-Based Questions

PBQs are where candidates either gain or lose the most ground. You might get up to 6 of them, and they test hands-on ability. Typical PBQ scenarios include configuring a network diagram with correct IP addresses and subnet masks, matching ports to services, troubleshooting a connectivity issue by analyzing command output, and setting up firewall rules or ACLs.

Partial credit is available. Even if you don't complete a PBQ perfectly, correctly placing some components earns points. Skip PBQs on your first pass through the exam and return to them after finishing the multiple-choice questions. They take more time, and you don't want to burn 10 minutes on one PBQ while leaving 5 multiple-choice questions unanswered.

Troubleshooting Methodology

The CompTIA troubleshooting model is a specific sequence, and the exam expects you to know it in order:

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 to resolve the problem and identify potential effects
5. Implement the solution or escalate as necessary
6. Verify full system functionality and implement preventive measures
7. Document findings, actions, and outcomes

Questions on this topic often describe a technician who skips a step and ask you to identify what was missed. A common trap: a tech identifies the problem, tests a solution, and it works. But they skip step 6 (verifying full system functionality) and just close the ticket. Two days later, a related issue surfaces because the fix caused a side effect. The correct answer is that the tech failed to verify full system functionality.

Command-line tools come up constantly in troubleshooting questions. Know what each one does and when to use it: ping tests basic connectivity, tracert/traceroute maps the path packets take, nslookup/dig queries DNS, ipconfig/ifconfig shows local network configuration, netstat shows active connections and listening ports, arp shows the MAC-to-IP mapping table, and pathping combines ping and tracert to identify packet loss at each hop.

Study Plan

Most candidates spend 8 to 12 weeks preparing for Network+. The exact timeline depends on your networking experience. If you already work with networks daily, you can compress this. If networking is new to you, give yourself the full 12 weeks.

Spend the first two weeks on Networking Concepts. Get the OSI model, TCP/IP, and subnetting solid before you touch anything else. Everything builds on this foundation. Weeks 3-4, move to Implementation: routing, switching, wireless. Weeks 5-6, Operations and Security. Weeks 7-8, Troubleshooting methodology and command-line tools. The remaining weeks should be full-length practice exams under timed conditions.

Subnetting and port numbers are the two areas where spaced repetition makes the biggest difference. These are pure memorization tasks with a lot of similar values that interfere with each other in memory. Drilling them in short, repeated sessions over weeks produces much stronger retention than cramming them the week before.

Exam Day

Ninety questions in 90 minutes is exactly one minute per question on average. PBQs take longer than that, so your multiple-choice pace needs to be faster. Answer multiple-choice questions first, flagging any you're unsure about, then tackle PBQs with whatever time remains.

Bring two forms of ID. You can't bring notes, phones, or calculators. Some testing centers provide a whiteboard or scratch paper; use it to write down subnetting reference tables and port numbers from memory before you start answering questions. This "brain dump" approach is legitimate and prevents exam stress from blanking out memorized material.