CWNA Wireless Network Administrator MCQ 3 — Questions and Answers
Question 1: Which IEEE 802.11 frame type is used by clients to discover available networks when active scanning?
- Beacon frame
- Probe request frame (Correct answer)
- Association request frame
- Authentication frame
Correct answer: Probe request frame
During active scanning, a client broadcasts probe request frames on each channel to solicit responses from nearby APs.
Question 2: A network administrator wants to enforce 128-bit CCMP encryption. Which security standard requires this as its mandatory cipher?
- WEP
- WPA (TKIP)
- WPA2 (Correct answer)
- 802.11i pre-standard
Correct answer: WPA2
WPA2 (ratified as 802.11i) mandates CCMP with AES-128 as its required encryption cipher, replacing TKIP used in WPA.
Question 3: What is the maximum EIRP (in dBm) typically allowed for point-to-multipoint 5 GHz UNII-1 (5.15–5.25 GHz) transmissions under FCC rules?
- 30 dBm
- 23 dBm (Correct answer)
- 36 dBm
- 17 dBm
Correct answer: 23 dBm
FCC rules limit UNII-1 (5.15–5.25 GHz) indoor devices to a maximum of 50 mW (17 dBm) conducted power with up to 6 dBi antenna gain, yielding ~23 dBm EIRP.
Question 4: Which roaming mechanism defined in 802.11r allows key negotiation to occur before a client fully reassociates, reducing roaming latency?
- PMK caching
- Opportunistic Key Caching (OKC)
- Fast BSS Transition (FT) (Correct answer)
- CCKM
Correct answer: Fast BSS Transition (FT)
802.11r Fast BSS Transition (FT) pre-negotiates cryptographic keys over the air or via the DS before reassociation, cutting roaming delay significantly.
Question 5: In a WPA3-Personal network, what replaces the traditional 4-way handshake pre-shared key exchange to resist offline dictionary attacks?
- EAP-PWD
- SAE (Simultaneous Authentication of Equals) (Correct answer)
- TKIP rekeying
- 802.1X port-based authentication
Correct answer: SAE (Simultaneous Authentication of Equals)
WPA3-Personal uses SAE, a password-authenticated key exchange based on the Dragonfly handshake, which provides forward secrecy and resists offline dictionary attacks.
Question 6: A site survey reveals significant multipath distortion in a warehouse. Which 802.11n/ac technology primarily mitigates multipath through spatial multiplexing?
- OFDM subcarrier spacing
- MIMO (Correct answer)
- Dynamic Frequency Selection (DFS)
- Short guard interval
Correct answer: MIMO
MIMO exploits multipath by using multiple antennas to transmit and receive independent data streams, turning multipath reflections into a benefit.
Question 7: What is the purpose of a guard interval (GI) in OFDM transmissions?
- Synchronize the clock between AP and client
- Prevent inter-symbol interference caused by multipath delay spread (Correct answer)
- Increase channel bandwidth
- Encrypt the preamble of each frame
Correct answer: Prevent inter-symbol interference caused by multipath delay spread
The guard interval is a brief pause between OFDM symbols that allows multipath echoes from the previous symbol to decay before the next symbol is sampled.
CWNA Wireless Network Administrator MCQ 3
Which IEEE 802.11 frame type is used by clients to discover available networks when active scanning?