CompTIA Network+ Preparation · lesson 11 of 30 · 25 min
IEEE 802.11 Standards
2.4 GHz vs 5 GHz
Wireless Security Standards
WPA2 Personal vs Enterprise
Personal (PSK): Pre-shared key — everyone uses the same password. Home/small office.Enterprise (802.1X): Each user authenticates with their own credentials via RADIUS server. Corporate networks.
Wireless Concepts
Flashcard Drill
802.11ac (Wi-Fi 5) 5 GHz only, up to 3.5 Gbps, MU-MIMO and beamforming — most common enterprise standard. 802.11ax (Wi-Fi 6) 2.4/5/6 GHz, 9.6 Gbps, OFDMA — designed for dense environments. Non-overlapping 2.4 GHz channels Channels 1, 6, and 11 — only three non-overlapping channels in the 2.4 GHz band. WPA2 Personal Pre-shared key (PSK) — everyone uses the same password. WPA2 Enterprise 802.1X authentication — each user has unique credentials via RADIUS. WEP Broken wireless security — cracked in minutes. Never use. WPA3 Latest wireless security — SAE replaces PSK, AES-GCMP-256 encryption. SSID Service Set Identifier — the wireless network name broadcast by an AP. MIMO Multiple Input Multiple Output — multiple antennas increase throughput. OFDMA Wi-Fi 6 feature — divides channels into sub-channels for multiple simultaneous users.
Worked Scenario: Wireless Troubleshooting
Scenario
Users in a conference room report slow Wi-Fi speeds and frequent disconnections. The AP is 802.11n on 2.4 GHz. A Wi-Fi analyzer shows channels 1, 6, and 11 are all heavily congested. What should the technician do?
Answer: Upgrade to 802.11ac or 802.11ax and switch to 5 GHz. The 2.4 GHz band only has 3 non-overlapping channels — in a dense environment they will all be congested. The 5 GHz band has 23+ non-overlapping channels and much less interference. Upgrading to 802.11ac (Wi-Fi 5) or 802.11ax (Wi-Fi 6) on 5 GHz will dramatically improve speed and reliability in the conference room.
Additionally, if the AP is shared with many users, 802.11ax with OFDMA would be the best choice — it’s specifically designed for dense, multi-user environments.
Knowledge Check — 12 Questions
Wireless Standards (Network+)
Which Wi-Fi standard operates on 5 GHz only and supports MU-MIMO?
- 802.11n
- 802.11g
- 802.11ac
- 802.11ax
Answer: 802.11ac
802.11ac (Wi-Fi 5) operates on 5 GHz only and introduced MU-MIMO and beamforming.
Which three 2.4 GHz channels are non-overlapping?
- 1, 2, 3
- 1, 6, 11
- 2, 7, 12
- 1, 5, 10
Answer: 1, 6, 11
Channels 1, 6, and 11 are the only non-overlapping channels in the 2.4 GHz band.
Which wireless security standard is considered broken and should never be used?
- WPA2
- WPA3
- WEP
- WPA
Answer: WEP
WEP uses RC4 encryption and can be cracked in minutes — completely insecure.
WPA2 Enterprise uses _____ for per-user authentication.
Answer: 802.1X
WPA2 Enterprise uses 802.1X with a RADIUS server for individual user authentication.
Which Wi-Fi standard introduced OFDMA for dense environments?
- 802.11ac
- 802.11n
- 802.11ax
- 802.11g
Answer: 802.11ax
802.11ax (Wi-Fi 6) introduced OFDMA, which divides channels for multiple simultaneous users.
The 5 GHz band has more non-overlapping channels than 2.4 GHz.
- True
- False
Answer: True
5 GHz has 23+ non-overlapping channels vs only 3 in the 2.4 GHz band.
What does SSID stand for?
- Secure Signal ID
- Service Set Identifier
- System Security ID
- Subnet Set Identifier
Answer: Service Set Identifier
SSID is the Service Set Identifier — the name of a wireless network broadcast by an AP.
Which band provides longer range but more interference?
- 5 GHz
- 6 GHz
- 2.4 GHz
- 60 GHz
Answer: 2.4 GHz
2.4 GHz has longer range and better wall penetration but suffers from more interference.
WPA3 replaces the PSK handshake with:
- TKIP
- AES-CCMP
- SAE
- RC4
- Answer: SAE
WPA3 uses SAE (Simultaneous Authentication of Equals) instead of the PSK 4-way handshake.
The MAC address of a specific access point is called the _____.
Answer: BSSID
BSSID (Basic Service Set Identifier) is the MAC address of the AP — uniquely identifies it.
Users in a dense conference room have slow Wi-Fi on 2.4 GHz. What is the best fix?
- Add more APs on 2.4 GHz
- Switch to 5 GHz with 802.11ac or 802.11ax
- Disable SSID broadcast
- Use WEP for faster encryption
Answer: Switch to 5 GHz with 802.11ac or 802.11ax
2.4 GHz has only 3 non-overlapping channels — congested in dense environments. 5 GHz has 23+ channels and higher speeds.
Which Wi-Fi standard is specifically designed for high-density environments with many simultaneous users?
- 802.11a
- 802.11n
- 802.11ac
- 802.11ax (Wi-Fi 6)
Answer: 802.11ax (Wi-Fi 6)
802.11ax (Wi-Fi 6) uses OFDMA to serve many users simultaneously — designed for dense environments like stadiums and conference rooms.
Try it: Wireless standards
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