In a Layer 1 passive wireless site survey using a channel analyzer tool (such as Metageek Chanalyzer or Cisco Spectrum Expert) in the 2.4 GHz spectrum, the chart that indicates the ratio of interference present during the capture duration is the Duty Cycle chart. The duty cycle chart displays the percentage of time that detected energy - including both Wi-Fi and non-Wi-Fi signals - is present on each channel. A high duty cycle on a channel indicates that the channel is occupied by transmissions for a significant portion of time, reducing available airtime for Wi-Fi clients. This chart directly communicates the ratio of interference because it shows what fraction of the observation period had detectable RF energy above the noise floor. Signal strength charts show amplitude (how strong), while duty cycle charts show temporal occupancy (how often) - the latter is the correct metric for quantifying interference ratio. Reference: WLSD Study Guide - Layer 1 Spectrum Analysis, Duty Cycle Chart Interpretation, Spectrum Analyzer Methodology.

The requirement for users to retain their VLAN assignment and IP address when roaming between buildings managed by different WLCs is a Layer 3 roaming scenario. In Cisco ' s wireless architecture, IP address preservation across controller boundaries is achieved through inter-controller mobility - specifically the foreign-anchor mobility tunnel mechanism. When a client roams from Building A (WLC-A) to Building B (WLC-B), WLC-B becomes the foreign controller and WLC-A becomes the anchor controller. WLC-B tunnels the client ' s traffic back to WLC-A, allowing the client to retain its original IP address even while physically associated to an AP managed by WLC-B. This requires creating a mobility group between WLC-A and WLC-B with both controllers configured with the same mobility group name - the group name is the trust identifier that permits the mobility tunnel and anchor-foreign relationship to form. An SSO cluster (Option B) creates redundancy between two WLCs operating as one logical entity, not inter-building roaming between independent controllers. 802.11r (Option C) accelerates re-association but does not preserve IP addresses across different Layer 3 subnets. AP groups (Option D) control SSID and VLAN assignments but do not enable inter-controller IP preservation. Reference: WLSD Study Guide - Inter-Controller Mobility, Layer 3 Roaming, IP Address Preservation.

The Cisco Aironet 2800 Series APs feature a dual-radio architecture with a dedicated 5 GHz radio (slot 1) and a Flexible Radio Assignment (XOR) radio (slot 0) that can operate in either 2.4 GHz or 5 GHz, or be assigned to monitor mode for scanning functions. Since all existing SSIDs and services are 5 GHz only, the slot 1 (dedicated 5 GHz) radio is responsible for all current client connectivity - it must remain in Client Serving mode to maintain uninterrupted 5 GHz WLAN service. The XOR radio (slot 0), currently either idle or operating as a secondary 5 GHz radio, can be repurposed without impacting client service. Setting the XOR radio to Monitor mode enables it to continuously scan all channels across both the 2.4 GHz and 5 GHz spectrum for rogue AP detection, using the embedded CleanAir and WIDS capabilities. In Monitor mode, the XOR radio operates full-time as a dedicated scanner, providing rogue detection coverage on 2.4 GHz (previously uncovered since all services were 5 GHz) and supplementary scanning on 5 GHz. This eliminates the need for additional dedicated monitor mode APs. Options A, C, and D either place the slot 1 radio in a non-client-serving role (disrupting existing connectivity) or use the inappropriate Sniffer mode instead of Monitor mode for rogue detection. Reference: WLSD Study Guide - Cisco 2800 XOR Radio Architecture, Monitor Mode for Rogue Detection, Flexible Radio Assignment, WIDS Design.

In a Cisco wireless mobility group, all Wireless LAN Controllers (WLCs) must be configured with the same virtual IP address to ensure proper roaming. The virtual IP address is a Layer 3 construct used by wireless clients during the DHCP renewal process when roaming between subnets managed by different WLCs. All WLCs in the same mobility group use the same virtual IP (typically from the unused 1.1.1.0/24 or similar non- routable space) so that clients receive consistent DHCP server responses regardless of which controller they are associated with. If different virtual IP addresses were used (Option B), clients roaming between controllers would experience DHCP failures during inter-controller roaming because the DHCP server address seen by the client would change. Options A and C relate to DNS hostname configuration, which is useful for AP discovery but does not affect the roaming behavior of client devices. The virtual IP address consistency across all mobility group members is a fundamental requirement for seamless inter-controller roaming. Reference: WLSD Study Guide - Mobility Group Configuration, Virtual IP Address, Inter- Controller Roaming Requirements.

Flex+Bridge mode is a specialized AP operating mode that combines two distinct Cisco wireless capabilities:
FlexConnect (for local switching of client data traffic and central authentication via the WLC) and Bridge
/Mesh mode (enabling wireless backhaul when no wired Ethernet uplink is available). In a branch environment without wired backhaul, a standard FlexConnect AP (Option D) cannot operate because FlexConnect still requires an Ethernet connection for its control plane. Bridge mode alone provides mesh backhaul but does not support the local switching with central authentication model required here. MAP (Option A) is a Mesh Access Point role for wireless backhaul, and RAP (Option C) is a Root Access Point with a wired connection - neither meets the no-wired-backhaul requirement with local switching.
Flex+Bridge uniquely satisfies both requirements: the Flex component allows locally switched VLANs to be bridged directly to the access layer without traversing the WAN, while the Bridge component enables the AP to use a wireless mesh link for its backhaul uplink. Central authentication is maintained via the CAPWAP control tunnel over the mesh link. Reference: WLSD Study Guide - FlexConnect Design, Mesh Networking, Flex+Bridge Mode Configuration and Use Cases.