CompTIA A+ Networking Practice Questions
Build foundational networking skills with practice questions on TCP/IP, ports, protocols, Wi-Fi standards, and connectivity troubleshooting for 2026.
Networking on the CompTIA A+ Exam
Networking fundamentals form a critical part of the CompTIA A+ certification, representing approximately 20% of the Core 1 exam. As an IT support technician, you will constantly interact with network infrastructure—configuring IP addresses, troubleshooting connectivity issues, setting up wireless networks, and understanding how data flows across LANs and WANs.
The A+ networking domain focuses on practical, entry-level skills. Unlike the Network+ certification which dives deep into network design and implementation, the A+ expects you to understand how networks work from an end-user support perspective. You need to configure network settings on client machines, identify when a problem is network-related versus hardware or software, and use command-line tools to diagnose issues.
Exam questions in this domain are heavily scenario-based. You might be presented with a user unable to access the internet, a printer that cannot be found on the network, or a VPN connection that keeps dropping. Your ability to systematically identify the layer of the problem (physical, data link, network, transport, or application) will determine your success.
Key Networking Concepts
🌐 TCP/IP Model
Four layers: Network Interface, Internet, Transport, and Application. Understand how data is encapsulated at each layer and the key protocols operating at each level.
🔢 IP Addressing
IPv4 addressing, subnet masks, CIDR notation, private address ranges (10.x, 172.16-31.x, 192.168.x), APIPA (169.254.x.x), and IPv6 basics including link-local addresses.
📡 Wireless Standards
Wi-Fi 5 (802.11ac), Wi-Fi 6 (802.11ax), Wi-Fi 6E, frequency bands (2.4 GHz vs 5 GHz vs 6 GHz), channel configuration, and wireless security protocols (WPA2, WPA3).
🔌 Network Devices
Routers, managed and unmanaged switches, wireless access points, firewalls, modems, network attached storage (NAS), and power over Ethernet (PoE) injectors.
🛠️ Troubleshooting Tools
ipconfig, ping, tracert, nslookup, netstat, pathping, and net commands. Know the output format and diagnostic value of each tool.
🔒 Network Services
DNS resolution process, DHCP lease cycle (DORA), NAT/PAT, proxy servers, VPN types, and common email protocols (SMTP, POP3, IMAP).
Essential Ports and Protocols
| Port | Protocol | Transport | Purpose |
|---|---|---|---|
| 20/21 | FTP | TCP | File transfer (data/control) |
| 22 | SSH | TCP | Secure remote access |
| 23 | Telnet | TCP | Unsecured remote access |
| 25 | SMTP | TCP | Email sending |
| 53 | DNS | TCP/UDP | Domain name resolution |
| 67/68 | DHCP | UDP | Dynamic IP assignment |
| 80 | HTTP | TCP | Web traffic (unencrypted) |
| 110 | POP3 | TCP | Email retrieval |
| 143 | IMAP | TCP | Email access (synced) |
| 443 | HTTPS | TCP | Secure web traffic |
| 445 | SMB | TCP | Windows file sharing |
| 3389 | RDP | TCP | Remote desktop |
Sample Networking Practice Question
Question: A user reports they cannot access any websites but can ping external IP addresses successfully. Internal network resources work fine. Which service is most likely experiencing an issue?
Correct Answer: B
Explanation: The user can ping IP addresses (proving Layer 3 connectivity works) but cannot access websites by name. This indicates DNS resolution is failing. If DHCP were the issue, the user would likely have no IP or an APIPA address. If the default gateway were down, pinging external IPs would also fail. NAT issues would prevent all external communication, not just name resolution.
Network Troubleshooting Methodology
When approaching network troubleshooting on the A+ exam, follow a bottom-up approach through the TCP/IP layers:
- Physical Layer: Check cable connections, link lights on NICs and switches, verify Wi-Fi is enabled, test with known-good cables
- Network Layer: Run ipconfig to verify IP configuration, check for APIPA addresses (169.254.x.x indicating DHCP failure), verify subnet mask and default gateway
- Connectivity: Ping localhost (127.0.0.1), ping default gateway, ping external IP (8.8.8.8), then ping a hostname to test DNS
- Name Resolution: Use nslookup to test DNS directly, try alternative DNS servers, check hosts file for overrides, flush DNS cache with ipconfig /flushdns
- Application Layer: Test specific services (HTTP, email), check firewall rules, verify proxy settings, clear browser cache
Study Checklist: Networking Domain
- ☐ Memorize all common ports (at least 15 port/protocol pairs)
- ☐ Explain the DHCP DORA process step by step
- ☐ Identify private vs public IP address ranges
- ☐ Use ipconfig, ping, tracert, and nslookup from memory
- ☐ Compare Wi-Fi standards and their maximum speeds
- ☐ Describe the DNS resolution process
- ☐ Differentiate between switches, routers, and access points
- ☐ Understand APIPA and what it indicates
Frequently Asked Questions
What networking topics are on the CompTIA A+ exam?
The A+ exam tests TCP/IP fundamentals, common ports and protocols, network device identification (routers, switches, access points), Wi-Fi standards, IP addressing and subnetting basics, DNS, DHCP, and basic network troubleshooting using command-line tools.
What ports should I memorize for the A+ networking exam?
Key ports include: HTTP (80), HTTPS (443), FTP (20/21), SSH (22), Telnet (23), SMTP (25), DNS (53), DHCP (67/68), POP3 (110), IMAP (143), RDP (3389), SMB (445), and LDAP (389). Know both TCP and UDP assignments.
How much of the A+ exam focuses on networking?
Networking represents approximately 20% of the Core 1 exam. This includes network types, devices, cables, TCP/IP addressing, and wireless standards. Additional network troubleshooting questions may appear across other domains.
Do I need to know subnetting for CompTIA A+?
Basic subnetting is tested on the A+ exam. You should understand default subnet masks for Class A, B, and C networks, CIDR notation, and be able to identify which devices are on the same subnet. Advanced subnetting calculations are more relevant for Network+.
What is the difference between TCP and UDP for the A+ exam?
TCP (Transmission Control Protocol) is connection-oriented, provides reliable delivery with acknowledgments, and uses a three-way handshake. UDP (User Datagram Protocol) is connectionless, faster but unreliable, used for streaming, DNS queries, and VoIP. Know which protocols use each.
What network troubleshooting tools are tested on A+?
You should know ipconfig/ifconfig, ping, tracert/traceroute, nslookup/dig, netstat, pathping, nbtstat, and net commands. Understand what each tool reveals and when to use it in a troubleshooting scenario.
Related CompTIA A+ Practice Resources
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