2.4 - Wireless standards and encryption

CompTIA A+ Core 1 objective 2.4 covers wireless standards, bands and encryption. 802.11ax (Wi-Fi 6E) first introduced support for the 6 GHz band, which is the least congested choice in a dense apartment building. Older 802.11ac (Wi-Fi 5) operates only on 5 GHz. For security, WPA2 uses the AES (CCMP) cipher for strong Wi-Fi encryption, and WPA3 is stronger still. You should also recognise fiber connectors such as LC, commonly used to terminate fiber-optic cabling. Expect scenario questions that describe a congestion, speed or security need and ask which wireless standard, band, cipher or connector is correct - matching the requirement to the newest suitable technology. When in doubt, the newest listed standard that meets the requirement is almost always the right pick.

Memory hook
6 GHz first support / least congested = Wi-Fi 6E (802.11ax). 5 GHz only = 802.11ac (Wi-Fi 5). WPA2 cipher = AES (CCMP); WPA3 stronger. Fiber connector = LC.

Practice questions

1. Which wireless standard FIRST introduced support for the 6 GHz frequency band?

  • 802.11ac (Wi-Fi 5)
  • 802.11n (Wi-Fi 4)
  • 802.11ax (Wi-Fi 6E) (correct answer)
  • 802.11g

Wi-Fi 6E is the '6 GHz extension' of 802.11ax. Wi-Fi 5 (ac) is 5 GHz only; Wi-Fi 4 (n) is 2.4/5 GHz.

2. A site needs the least congested Wi-Fi in a dense apartment building. Which band/standard is BEST?

  • 2.4 GHz using 802.11n
  • 6 GHz Wi-Fi 6E (802.11ax) (correct answer)
  • 2.4 GHz using 802.11g
  • 5 GHz using 802.11a

Wi-Fi 6E adds the 6 GHz band, which is much less crowded than 2.4/5 GHz — ideal in dense environments.

3. Which encryption cipher is used with WPA2 for strong Wi-Fi security?

  • WEP (weak)
  • TKIP (older)
  • AES (CCMP) (correct answer)
  • DES (broken)

WPA2 uses AES (CCMP) for strong encryption. TKIP is older/weaker; WEP is broken.

4. Which connector is commonly used to terminate fiber-optic cabling?

  • RJ45
  • LC (correct answer)
  • BNC
  • RJ11

LC (and SC/ST) are fiber connectors. RJ45=copper Ethernet, RJ11=phone, BNC=legacy coax.

5. Which 802.11 standard introduced multi-user MIMO and operates on 2.4 and 5 GHz, branded Wi-Fi 6?

  • 802.11n
  • 802.11ac (correct answer)
  • 802.11ax
  • 802.11g

802.11ax (Wi-Fi 6/6E) improves efficiency (OFDMA, MU-MIMO) on 2.4/5 GHz, plus 6 GHz for 6E.

6. Which protocols are common for smart-home (low-power IoT mesh) devices?

  • HTTP and FTP
  • SMTP and POP3
  • Zigbee and Z-Wave (correct answer)
  • Telnet and SSH

Zigbee and Z-Wave are low-power mesh protocols for smart-home sensors/devices; segment them for security.

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