CWS CWS Wi-Fi Service Sets 4 — Questions and Answers
Question 1: Which of the following best describes an ESSID?
- The MAC address of the AP radio
- The common SSID name shared across all BSSes in an ESS (Correct answer)
- The VLAN tag assigned to a BSS
- A unique identifier per client device
Correct answer: The common SSID name shared across all BSSes in an ESS
An ESSID (Extended Service Set Identifier) is simply the human-readable SSID name shared by all APs forming the ESS.
Question 2: Why does using many SSIDs on a single AP negatively impact network performance?
- Each SSID uses a different encryption algorithm
- Each SSID requires periodic beacons that consume airtime (Correct answer)
- Each SSID requires a dedicated physical antenna
- SSIDs cause channel overlap
Correct answer: Each SSID requires periodic beacons that consume airtime
Each SSID generates its own beacon frames at the beacon interval, consuming shared airtime and reducing capacity for data traffic.
Question 3: In infrastructure BSS mode, all client-to-client frames must pass through which device?
- The DHCP server
- The DNS server
- The Access Point (Correct answer)
- The gateway router
Correct answer: The Access Point
In a BSS, the AP is the central hub; all frames between associated clients must be forwarded through the AP.
Question 4: A wireless network analyst sees two APs broadcasting the same SSID and connected by Ethernet. What type of service set is this?
- IBSS
- Single BSS
- ESS (Correct answer)
- MBSS
Correct answer: ESS
Two or more APs sharing the same SSID and connected via a wired DS form an ESS, enabling client roaming.
Question 5: What is the primary security risk of SSID suppression (hidden SSID)?
- It disables WPA2/WPA3 encryption
- Probe requests expose the SSID in cleartext during active scanning (Correct answer)
- It forces clients to use open authentication
- Hidden SSIDs cannot use 802.1X
Correct answer: Probe requests expose the SSID in cleartext during active scanning
Clients that have previously connected must send probe requests containing the SSID in plaintext to reconnect, exposing it to passive capture.
Question 6: In an 802.11 frame, the BSSID field in the MAC header serves what purpose?
- It identifies which distribution system the frame is headed to
- It identifies which BSS the frame belongs to (Correct answer)
- It specifies the encryption suite in use
- It indicates the transmit power level
Correct answer: It identifies which BSS the frame belongs to
The BSSID field in the 802.11 MAC header identifies the specific BSS (i.e., the AP's radio MAC) that the frame is associated with.
Question 7: A hotel deploys one SSID for guests and a separate SSID for staff on the same AP hardware. What is the benefit of this multi-SSID approach?
- Each SSID uses a different Wi-Fi standard
- Each SSID can be mapped to a separate VLAN for traffic isolation (Correct answer)
- Each SSID operates on a different frequency band automatically
- Each SSID has its own IP routing table
Correct answer: Each SSID can be mapped to a separate VLAN for traffic isolation
Multi-SSID with VLAN mapping allows logical traffic separation so guest and staff traffic never mix, even on shared AP hardware.
CWS CWS Wi-Fi Service Sets 4
Which of the following best describes an ESSID?