CompTIA Network+ Preparation · lesson 15 of 30 · 25 min
IEEE 802.11 Wireless Standards
Wi-Fi is based on the IEEE 802.11 standard family. Each amendment adds speed, frequency, or feature improvements. The Network+ exam tests the key amendments and their characteristics.
2.4 GHz vs 5 GHz: 2.4 GHz has longer range but more interference (microwaves, Bluetooth, neighboring networks). 5 GHz has shorter range but faster speeds and less interference. Wi-Fi 6 adds the 6 GHz band (Wi-Fi 6E).
Channels: 2.4 GHz has 11 channels in the US; only channels 1, 6, and 11 are non-overlapping. 5 GHz has many non-overlapping channels — much less congestion.
MIMO (Multiple Input Multiple Output) — uses multiple antennas to send/receive multiple data streams simultaneously. MU-MIMO (Multi-User MIMO) allows the AP to communicate with multiple clients at the same time.
OFDMA (Orthogonal Frequency Division Multiple Access) — Wi-Fi 6 feature that divides a channel into sub-channels, allowing multiple clients to transmit simultaneously. Improves efficiency in dense environments.
Exam Tip
Know the speeds: 802.11n=600Mbps, 802.11ac=3.5Gbps, 802.11ax=9.6Gbps. 802.11ac is 5 GHz only. 802.11n and ax are dual-band. Non-overlapping 2.4 GHz channels: 1, 6, 11.
Wireless Security
WEP (Wired Equivalent Privacy) — original Wi-Fi security. Broken and deprecated. Uses RC4 with static keys. Never use.
WPA (Wi-Fi Protected Access) — replaced WEP. Uses TKIP encryption. Also deprecated — vulnerable to attacks.
WPA2 — current standard. Uses AES-CCMP encryption. Personal mode (PSK — pre-shared key) and Enterprise mode (802.1X with RADIUS authentication).
WPA3 — latest standard. SAE (Simultaneous Authentication of Equals) replaces PSK — resistant to offline dictionary attacks. Forward secrecy. Required for Wi-Fi 6 certification.
802.1X / EAP — enterprise wireless authentication. Client authenticates to a RADIUS server before gaining network access. Requires a RADIUS server and certificates or credentials.
Key Terms
Key Terms
Knowledge Check — 10 Questions
Network+ — Wireless Standards
Which 802.11 standard operates on 5 GHz only?
- 802.11b
- 802.11g
- 802.11ac
- 802.11n
Answer: 802.11ac
802.11ac (Wi-Fi 5) operates exclusively on 5 GHz. 802.11n and 802.11ax are dual-band (2.4 + 5 GHz).
What is the maximum theoretical speed of 802.11ax (Wi-Fi 6)?
- 600 Mbps
- 1.3 Gbps
- 3.5 Gbps
- 9.6 Gbps
Answer: 9.6 Gbps
Wi-Fi 6 (802.11ax) = 9.6 Gbps theoretical max. Wi-Fi 5 (802.11ac) = 3.5 Gbps. Wi-Fi 4 (802.11n) = 600 Mbps.
Which 2.4 GHz channels are non-overlapping?
- 1, 2, 3
- 1, 6, 11
- 1, 5, 10
- 2, 7, 12
Answer: 1, 6, 11
In the US, 2.4 GHz has 11 channels but only 1, 6, and 11 are non-overlapping — use these to avoid co-channel interference.
WPA2-Enterprise uses which authentication method?
- Pre-shared key (PSK)
- 802.1X with RADIUS
- WEP keys
- SAE
Answer: 802.1X with RADIUS
WPA2-Enterprise uses 802.1X — clients authenticate to a RADIUS server with credentials or certificates, not a shared password.
Which wireless security protocol should never be used?
- WPA3
- WPA2
- WPA
- WEP
Answer: WEP
WEP is completely broken — it can be cracked in minutes. Never use WEP. WPA is also deprecated. Use WPA2 or WPA3.
SAE in WPA3 protects against:
- Signal interference
- Offline dictionary attacks on the passphrase
- Rogue access points
- Channel overlap
- Answer: Offline dictionary attacks on the passphrase
SAE (Simultaneous Authentication of Equals) replaces PSK — even if an attacker captures the handshake, they cannot crack the password offline.
OFDMA is a key feature of which Wi-Fi standard?
- 802.11ac
- 802.11n
- 802.11ax
- 802.11g
Answer: 802.11ax
OFDMA is introduced in Wi-Fi 6 (802.11ax) — divides channels into resource units for simultaneous multi-client communication.
5 GHz Wi-Fi compared to 2.4 GHz has:
- Longer range and more interference
- Shorter range but faster speeds and less interference
- Same range and speed
- Lower frequency and higher speed
- Answer: Shorter range but faster speeds and less interference
Higher frequency = shorter range (absorbed more by walls) but more available channels, less interference, and higher speeds. MU-MIMO allows:
- Multiple APs to share one channel
- An AP to communicate with multiple clients simultaneously
- Clients to use multiple SSIDs
- Automatic channel selection
- Answer: An AP to communicate with multiple clients simultaneously
MU-MIMO (Multi-User MIMO) lets the AP transmit to multiple clients at the same time — improves throughput in busy environments.
WPA2 uses _____ encryption (the current strong standard).
Answer: AES
WPA2 uses AES-CCMP encryption. WPA used TKIP (weaker). WEP used RC4 (broken). AES is the current strong standard.
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