2.3 Given a scenario, select and configure wireless devices and technologies
Frequency Options
📘CompTIA Network+ (N10-009)
5 GHz Frequency – CompTIA Network+ (N10-009)
The 5 GHz frequency is one of the two main frequency bands used in Wi-Fi networks (the other is 2.4 GHz). It’s part of the IEEE 802.11 standards, commonly used in Wi-Fi networks like 802.11a, 802.11n, 802.11ac, and 802.11ax (Wi-Fi 6).
Here’s what you need to know for the exam:
1. Frequency Basics
- Frequency: This is the number of times a wave repeats per second. Higher frequencies can carry more data but may have a shorter range.
- 5 GHz is higher than 2.4 GHz, which has several effects:
- Higher data rates → Faster network speeds.
- Shorter range → Doesn’t travel as far through walls or obstacles.
- Less interference → Fewer devices operate on 5 GHz, so it’s cleaner.
2. Channels and Overlap
- 5 GHz has more channels than 2.4 GHz, which reduces interference.
- Non-overlapping channels: Unlike 2.4 GHz, which has only 3 non-overlapping channels (1, 6, 11), 5 GHz has up to 23 non-overlapping channels, depending on the regulatory domain.
- DFS (Dynamic Frequency Selection): Some 5 GHz channels require devices to avoid interference with radar systems. Access points may switch channels automatically if radar signals are detected.
Why it matters in IT environments:
- In offices with many Wi-Fi networks, 5 GHz reduces overlap and interference.
- Better for high-density environments like offices, schools, or hospitals.
3. Wi-Fi Standards Using 5 GHz
| Standard | Max Speed | Key Notes |
|---|---|---|
| 802.11a | 54 Mbps | Early 5 GHz standard |
| 802.11n | 600 Mbps (with MIMO) | Can use 2.4 GHz or 5 GHz (dual-band) |
| 802.11ac | 1.3 Gbps+ | 5 GHz only; supports wider channels (80 MHz, 160 MHz) |
| 802.11ax (Wi-Fi 6) | 9.6 Gbps | Can use 2.4 GHz or 5 GHz; better efficiency, OFDMA |
Important points for the exam:
- 5 GHz is often faster than 2.4 GHz but has shorter coverage.
- Used in modern Wi-Fi networks, especially for high-speed applications like video streaming, video conferencing, or transferring large files.
4. Advantages of 5 GHz
- Higher throughput: More bandwidth means faster speeds.
- Less interference: Fewer devices (cordless phones, microwave ovens) use this band.
- More channels: Reduces congestion in high-density Wi-Fi environments.
5. Disadvantages of 5 GHz
- Shorter range: Doesn’t penetrate walls or floors as well as 2.4 GHz.
- Compatibility: Older devices may not support 5 GHz (802.11a/n/ac/ax required).
- DFS restrictions: Some channels may not always be available in certain regions due to radar interference.
6. Practical Use in IT Environments
- Enterprise Wi-Fi networks: Use 5 GHz to provide fast connections for employees’ laptops and devices.
- High-density areas: Offices, classrooms, and conference rooms use 5 GHz to prevent interference from multiple Wi-Fi networks.
- Data centers or server rooms: Wi-Fi devices on 5 GHz can transfer large amounts of data quickly for backups or large file access.
- Guest networks: Many IT admins separate guest Wi-Fi on 5 GHz to keep traffic fast and isolated from critical internal systems.
7. Key Exam Points
- 5 GHz = higher speed, shorter range, less interference.
- 5 GHz channels = more non-overlapping options → better for crowded networks.
- Common Wi-Fi standards on 5 GHz: 802.11a/n/ac/ax.
- DFS channels exist → APs may change channels automatically.
- Ideal for high-bandwidth applications like video streaming, VoIP, large file transfers, and dense Wi-Fi environments.
Quick Tip for Memory
Think of 5 GHz as the “fast but short-range” Wi-Fi band: it moves data quickly, avoids interference, but doesn’t reach as far as 2.4 GHz.
