Wi-Fi Standards for Network+: 802.11a/b/g/n/ac/ax Compared
Wireless networking is a core domain on the CompTIA Network+ N10-009 exam. You must know the differences between 802.11 standards, including frequency bands, maximum data rates, channel widths, and MIMO configurations. This guide covers every 802.11 variant you'll encounter on the exam, with practical tips for identifying the correct standard from scenario-based questions.
802.11a – 5 GHz Pioneer
Introduced in 1999, 802.11a operates exclusively in the 5 GHz band. It uses OFDM (Orthogonal Frequency Division Multiplexing) and supports a maximum data rate of 54 Mbps. Channel width is fixed at 20 MHz. No MIMO support – it's single-input single-output (SISO).
Exam note: 802.11a is rarely used today but may appear in legacy or interference-rich environments where 2.4 GHz is congested.
802.11b – The 2.4 GHz Workhorse
Also from 1999, 802.11b uses the 2.4 GHz band with DSSS (Direct Sequence Spread Spectrum). Maximum data rate is 11 Mbps, channel width 20 MHz, SISO only. Range is better than 802.11a due to lower frequency, but throughput is much lower.
Exam note: 802.11b is backward compatible with 802.11g and 802.11n (when operating in mixed mode). It's the slowest standard you'll see on the exam.
802.11g – Bridging the Gap
Released in 2003, 802.11g operates at 2.4 GHz but uses OFDM, achieving up to 54 Mbps – same as 802.11a but with better range. Channel width remains 20 MHz, no MIMO. It is backward compatible with 802.11b.
Exam tip: If a question mentions a 2.4 GHz network with 54 Mbps maximum speed, it's 802.11g (or 802.11a, but that's 5 GHz).
802.11n – The MIMO Revolution
802.11n (Wi-Fi 4) introduced MIMO (Multiple-Input Multiple-Output) and channel bonding. It operates in both 2.4 GHz and 5 GHz bands. Maximum data rate is 600 Mbps (with 4×4 MIMO and 40 MHz channels). Standard channel widths: 20 MHz and 40 MHz. MIMO allows multiple spatial streams (up to 4).
Key exam detail: 802.11n can use either frequency band. In the exam, if a scenario mentions "dual-band" or "MIMO," think 802.11n or later.
802.11ac – Gigabit Wi-Fi
802.11ac (Wi-Fi 5) operates only in 5 GHz. It builds on 802.11n with wider channels (up to 160 MHz), more MIMO streams (up to 8), and MU-MIMO (Multi-User MIMO) in Wave 2. Maximum data rate exceeds 1 Gbps (theoretical up to 6.9 Gbps with 8×8 MIMO and 160 MHz).
Exam tip: 802.11ac is 5 GHz only. If a question says "5 GHz" and "high throughput," it's likely ac. MU-MIMO is a key differentiator from n.
802.11ax – Wi-Fi 6
The latest standard on the exam, 802.11ax (Wi-Fi 6), operates in both 2.4 GHz and 5 GHz (and soon 6 GHz with Wi-Fi 6E). It introduces OFDMA (Orthogonal Frequency Division Multiple Access), which improves efficiency in dense environments. Maximum data rate is up to 9.6 Gbps. Channel widths: 20, 40, 80, 160 MHz. Supports MU-MIMO in both uplink and downlink.
Exam note: 802.11ax is backward compatible with a/b/g/n/ac. Look for keywords like "OFDMA" or "high-density" to identify ax.
Comparison Table
| Standard | Band | Max Speed | Channel Width | MIMO | Key Feature |
|---|---|---|---|---|---|
| 802.11a | 5 GHz | 54 Mbps | 20 MHz | No | OFDM |
| 802.11b | 2.4 GHz | 11 Mbps | 20 MHz | No | DSSS |
| 802.11g | 2.4 GHz | 54 Mbps | 20 MHz | No | OFDM, backward compatible with b |
| 802.11n | 2.4/5 GHz | 600 Mbps | 20/40 MHz | Yes (up to 4 streams) | MIMO, channel bonding |
| 802.11ac | 5 GHz | >1 Gbps | 20/40/80/160 MHz | Yes (up to 8 streams) | MU-MIMO (Wave 2) |
| 802.11ax | 2.4/5 GHz | 9.6 Gbps | 20/40/80/160 MHz | Yes (up to 8 streams) | OFDMA, improved efficiency |
What to Watch for on the Exam
- Frequency band: If a question mentions only 5 GHz, eliminate b/g. If dual-band, consider n or ax.
- Speed: 54 Mbps points to a or g. 11 Mbps is b. 600 Mbps is n. Gigabit+ is ac or ax.
- MIMO: Any mention of multiple antennas or spatial streams means n or later.
- MU-MIMO: Only present in 802.11ac Wave 2 and 802.11ax.
- OFDMA: Exclusive to 802.11ax.
- Backward compatibility: g works with b; n works with a/b/g; ac works with a/b/g/n; ax works with all.
- Channel width: 40 MHz channels are possible with n; 80/160 MHz with ac/ax.
Conclusion
Mastering 802.11 standards is essential for the Network+ exam. Focus on frequency, speed, MIMO, and channel width to differentiate each standard. Practice identifying standards from scenario descriptions – for example, a 5 GHz network with 160 MHz channels and MU-MIMO is 802.11ac.
Test your knowledge with practice questions that ask you to select the correct standard based on given parameters. Use flashcards for quick recall of speeds and features.
Ready to gauge your understanding? Try our free Network+ wireless practice quiz at [example.com/networkplus-wireless-quiz] to reinforce these concepts before exam day.