Optimizing Roaming for Shopping Center Shops with Unique WLANs
An engineer has been tasked with optimizing roaming for all the wireless networks used by shops located in a shopping center. A unique WLAN is assigned to each individual shop named ret470632970B55XX, where the last two digits indicate the shop’s location. The wireless network consists of 9800 controllers and Cisco 9100 APs. What should the engineer configure on the controllers to optimize roaming?
Community Votes
100% of anonymous learners picked answer D. Votes are pick records left by other test-takers — they are not the verified answer.
Community Insight
The question tests Cisco 9800 controller interface configuration for roaming optimization in a high-density multi-WLAN environment; the trap is confusing security or radio settings with the VLAN-to-WLAN mapping needed for Layer 2 roaming.
Optimizing client roaming in a multi-WLAN shopping center requires mapping each shop's WLAN to a dedicated interface on the Cisco 9800 controller. This page explains why creating an interface per shop (D) is the correct answer and why the other options fail to improve roaming.
Many candidates choose to disable the 802.11a/b network (B) thinking it reduces interference, but disabling both bands would eliminate Wi-Fi entirely; others pick access rules (A) which are for security, not roaming.
Community Discussion (3 comments)
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Expert Analysis
Why the Answer Is Correct
The correct answer is D: create an interface per shop. In a shopping center where each shop has a unique WLAN (e.g., ret470632970B55XX), the Cisco 9800 controller must map each WLAN to a dedicated VLAN interface. This ensures that clients associated with a shop's WLAN remain on the same subnet as they roam between the Cisco 9100 APs within that shop, enabling seamless Layer 2 roaming. Without per-shop interfaces, all WLANs might share a single interface, which can lead to unnecessary Layer 3 roaming or broadcast domain issues. By creating an interface per shop, the engineer isolates traffic and provides the stable subnet required for fast, reliable roaming. This design aligns with Cisco's best practices for high-density wireless networks, where logical separation of WLANs optimizes client mobility.
Why the Other Options Are Wrong
Option A (assign access rules based on location) is a security measure that can restrict which APs a client can use, but it does not optimize roaming and could even hinder it by preventing clients from associating with the best AP. Option B (disable the 802.11a/b network) would disable both the 5 GHz and 2.4 GHz radios, effectively turning off Wi-Fi; even if it meant disabling only 2.4 GHz, the option as written is incorrect and not a controller-wide roaming optimization. Option C (enable AES encryption) is a security setting for WLAN encryption; while AES is recommended for security, it has no impact on roaming performance or client mobility. None of these options address the fundamental need for proper VLAN-to-WLAN mapping that supports Layer 2 roaming.
Community Comment Notes
The community unanimously voted for D, with Farhad123 stating, "D is correct, the other choices dont help optimize roaming". Bembs simply confirmed, "D is the right answer". One commenter, Rododendron2, expressed frustration that "no answer makes sense to me", reflecting the confusing wording of the question, but the consensus still points to D as the intended answer. These comments highlight that while the question is poorly phrased, the exam key and community agree on creating an interface per shop.
Exam Strategy
When a question asks about optimizing roaming in a multi-WLAN environment, look for the option that addresses VLAN or subnet design, as Layer 2 roaming requires the client to keep its IP address. Options that change security, disable radios, or add ACLs are usually distractors.
Frequently Asked Questions
Why does creating an interface per shop optimize roaming in a Cisco 9800 environment?
It maps each shop's WLAN to a unique VLAN, so clients roaming within the shop stay on the same subnet and achieve Layer 2 roaming without changing IP addresses.
Can disabling the 802.11a/b network improve roaming in a shopping center?
No, disabling both bands would disable Wi-Fi entirely; roaming optimization focuses on VLAN design and fast transition protocols, not turning off radios.