CCIE Wireless (legacy) — Question 6

Which two statements about 802.11ac wireless LAN technology are true? (Choose two.)

Answer options

• A. Antenna design does have to change because 802.11ac occupies different spectrum as 802.11a and 802.11n at 5 GHz
• B. The 802.11ac IEEE standard allows for theoretical speeds up to 6.9 Gbps in the 5 GHz band, which is 11,5 times those of 802.11n
• C. The 802.11ac standard defines downlink and uplink MU-MIMO, which is for the access point sending to multiple clients concurrently and for multiple clients coordinating to transmit separate packets to the access point at the same time
• D. The 802.11ac Wave 2 standard limits itself to communicating with a maximum of four clients at a time, using up to a total of eight spatial streams (for all clients) or a maximum of four spatial streams per client in a MU-MIMO transmission
• E. Client MU-MIMO (802.11ac Wave 2) can be achieved easily via software upgrade assuming the client is at least 802.11ac Wave 1 compatible

Correct answer: B, C

Explanation

Option B is correct because it accurately describes the theoretical maximum speed of 802.11ac compared to 802.11n. Option C is also correct as it explains the MU-MIMO capabilities of the 802.11ac standard. Option A is incorrect because the antenna design does not necessarily change due to spectrum usage, and option D misrepresents the capability of 802.11ac Wave 2, which can support more than four clients. Option E is misleading as client MU-MIMO requires specific hardware support, not just a software upgrade.