Study guide · Network+

CompTIA Network+ Practice Test (N10-009)

270 practice questions mapped to the N10-009 exam objectives — with full explanations for every answer. Identify your weak domains before exam day.

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About the Network+ N10-009 exam

CompTIA Network+ (N10-009) is the leading vendor-neutral networking certification for IT professionals. It validates the skills needed to establish, maintain, troubleshoot, and secure networks. N10-009 launched in 2024 with updated content on cloud networking, automation, and security.

The exam allows up to 90 questions, 90-minute time limit, and a passing score of 720 (on a 100–900 scale). Questions include multiple choice, drag-and-drop, and performance-based items.

N10-009 exam domains

23%

Networking Concepts

20%

Network Implementation

19%

Network Operations

14%

Network Security

24%

Network Troubleshooting

Sample Network+ practice questions

A network technician needs to divide the 192.168.10.0/24 network into subnets that each support at least 50 hosts. Which subnet mask should be used?

A. /26 (255.255.255.192)

B. /26 — wait. A /26 gives 62 usable hosts. But the question is which mask supports at least 50. /26 = 62 hosts ✓

B. 255.255.255.192 (/26) ✓

C. 255.255.255.224 (/27)

D. 255.255.255.240 (/28)

A /26 mask (255.255.255.192) gives 2^6 - 2 = 62 usable host addresses per subnet. A /27 gives only 30 usable hosts, which is below the 50 required. A /28 gives 14. The formula is 2^(host bits) - 2, subtracting 2 for the network and broadcast addresses.

Which protocol uses TCP port 443 and provides encrypted communication for web traffic?

A. HTTP

B. FTP

C. HTTPS ✓

D. SFTP

HTTPS (HTTP Secure) runs over TLS/SSL and uses TCP port 443. It encrypts the HTTP communication between client and server. HTTP uses port 80 (unencrypted). FTP uses ports 20/21. SFTP (SSH File Transfer Protocol) uses port 22.

A user reports they cannot access external websites but can ping internal servers by IP. DNS resolves correctly for internal hostnames. What is the most likely cause?

A. The user's NIC is faulty

B. The switch port has VLAN misconfiguration

C. The default gateway is not configured or is unreachable ✓

D. The DHCP server is down

The ability to reach internal servers by IP means the NIC and local network are working. Inability to reach external destinations (outside the local subnet) points to a missing or incorrect default gateway — the router the device sends traffic to when the destination is outside its subnet. If DHCP were down, the device likely wouldn't have an IP at all.

How to prepare for Network+

Network Troubleshooting is the largest domain

At 24% of the exam, troubleshooting questions are the biggest domain. Practice working through issues methodically using the OSI model — start physical (Layer 1) and work up. Recognize symptoms at each layer: no link light (Layer 1), duplicate MAC (Layer 2), wrong subnet mask (Layer 3), wrong port (Layer 4).

Subnetting must be fast

Subnetting questions appear in multiple domains. Know your powers of 2 and be able to calculate subnet sizes, usable hosts, and broadcast addresses quickly. Under exam time pressure, slow subnetting loses you points on questions you know.

Know your ports and protocols

Network+ expects you to know the port numbers for common services: SSH (22), DNS (53), HTTP (80), HTTPS (443), SMB (445), RDP (3389), and many more. Also know which use TCP, which use UDP, and why. These are quick points if you've memorized them.

270 Network+ questions with full explanations

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