Cisco CCNA WLAN Architectures and Concepts Questions and Answers — Questions and Answers
Question 1: A network administrator is designing a wireless network for a large corporate campus with hundreds of access points. The requirements include centralized management, seamless client roaming, and consistent policy enforcement. Which WLAN architecture is BEST suited for this scenario?
- Ad-hoc mode
- Autonomous AP architecture
- Controller-based architecture (Correct answer)
- Cloud-based architecture with each AP managed individually
Correct answer: Controller-based architecture
A controller-based architecture, also known as a Split-MAC architecture, is the ideal solution for large-scale enterprise deployments. It uses a central Wireless LAN Controller (WLC) to manage all lightweight access points (LAPs), providing centralized configuration, policy enforcement, firmware updates, and facilitating seamless roaming. [2, 5, 8] Autonomous APs require individual configuration, which is not scalable. [1, 2] Ad-hoc mode is for peer-to-peer connections without an AP. Cloud-based management is a valid option, but managing each AP individually negates the benefits of centralization required for this scale.
Question 2: In a controller-based WLAN architecture using CAPWAP, what is the primary function of the 'Split-MAC' concept?
- It allows a single AP to use multiple MAC addresses to serve different SSIDs.
- It divides the 802.11 MAC functions between the Lightweight Access Point (LAP) and the Wireless LAN Controller (WLC). (Correct answer)
- It enables MAC filtering to be performed at either the AP or the switch, but not both.
- It splits the wireless traffic into separate tunnels for data and voice.
Correct answer: It divides the 802.11 MAC functions between the Lightweight Access Point (LAP) and the Wireless LAN Controller (WLC).
The Split-MAC architecture is a fundamental concept in controller-based WLANs. It divides the 802.11 MAC operations, assigning real-time functions (like beaconing and probe responses) to the Lightweight Access Point, while the Wireless LAN Controller handles less time-sensitive management functions (like authentication and association). [3, 7, 17] This allows for centralized control while keeping time-critical operations close to the client.
Question 3: A company needs to deploy a wireless access point in a small, remote branch office with an unreliable WAN link to the central headquarters where the WLC is located. The goal is to allow wireless clients to continue accessing local resources even if the WAN link fails. Which AP mode should the administrator configure?
- Local Mode
- Monitor Mode
- Sniffer Mode
- FlexConnect Mode (Correct answer)
Correct answer: FlexConnect Mode
FlexConnect mode is specifically designed for remote/branch office deployments. In this mode, if the CAPWAP tunnel to the WLC is down, the AP can switch traffic locally between the wireless clients and the wired LAN, allowing access to local resources. [4, 20, 23] Local mode, the default, requires the CAPWAP tunnel to be active as it tunnels all traffic back to the WLC. [20, 25] Monitor and Sniffer modes are used for network monitoring and troubleshooting, not for serving clients. [4]
Question 4: Which of the following correctly describes the CAPWAP tunnels established between a Lightweight Access Point (LAP) and a Wireless LAN Controller (WLC)?
- A single encrypted TCP tunnel is used for both control and data traffic on port 5246.
- Two separate UDP tunnels are used: a data tunnel on port 5246 and a control tunnel on port 5247.
- A single unencrypted UDP tunnel is used for all traffic to maximize performance.
- Two separate UDP tunnels are used: a control tunnel on port 5246 and a data tunnel on port 5247. (Correct answer)
Correct answer: Two separate UDP tunnels are used: a control tunnel on port 5246 and a data tunnel on port 5247.
CAPWAP establishes two distinct UDP tunnels between the LAP and WLC. The control tunnel operates on UDP port 5246 and is used for management and control traffic; it is secured by default with DTLS encryption. The data tunnel operates on UDP port 5247 and is used to encapsulate and forward client data; it is unencrypted by default. [3, 7, 14, 26]
Question 5: A wireless client roams from an AP associated with WLC1 to an AP associated with WLC2. Both WLCs are in the same mobility group, but the client is assigned to a different VLAN/subnet after roaming. To maintain the client's session and IP address, what type of roaming occurs?
- Intra-controller Roaming
- Layer 2 Inter-controller Roaming
- Layer 3 Inter-controller Roaming (Correct answer)
- Static Channel Roaming
Correct answer: Layer 3 Inter-controller Roaming
When a wireless client roams between APs connected to different WLCs and moves to a new VLAN/subnet, it is called a Layer 3 Inter-controller roam. To ensure seamless connectivity, the original WLC becomes the 'anchor' controller, and a mobility tunnel (often a CAPWAP or EoIP tunnel) is built between the anchor and the new 'foreign' controller. This allows the client to keep its original IP address by tunneling its traffic back to the original subnet. [13, 16, 21]
Question 6: What is a primary characteristic of an autonomous WLAN architecture?
- It relies on a cloud-based dashboard for all configuration and firmware updates.
- Each access point is individually configured and manages its own settings, security, and client associations. (Correct answer)
- All client traffic is tunneled back to a central appliance using the CAPWAP protocol.
- It requires a dedicated Wireless LAN Controller (WLC) on the local network.
Correct answer: Each access point is individually configured and manages its own settings, security, and client associations.
An autonomous AP is a self-contained, standalone device. Each AP is configured and managed individually, typically via a CLI or web GUI. It handles all functions locally, including user authentication, security policies, and RF management, without the need for a WLC. [1, 2, 5] This architecture is simple for small deployments but becomes difficult to manage at scale. [2, 15]
Cisco CCNA WLAN Architectures and Concepts Questions and Answers
A network administrator is designing a wireless network for a large corporate campus with hundreds of access points.
The requirements include centralized management, seamless client roaming, and consistent policy enforcement.
Which WLAN architecture is BEST suited for this scenario?