The administrative distance is used as a trust rating for route entries (B). It is a metric used by routers to select the best path when there are two or more different routes to the same destination from two different routing protocols. The lower the administrative distance value, the more trustworthy the source of the route. For example, a directly connected network has an administrative distance of 0 because it is the most trusted source of routing information. In contrast, routes learned from different routing protocols have higher administrative distances, reflecting their relative trustworthiness.

In a Virtual Switching Extension (VSX) stack, the Virtual IP (VIP) provides a single default gateway IP address for clients connected to the access switch. This VIP is a floating IP that is active on the primary VSX switch. In the event of a failure of the primary switch, the VIP will failover to the secondary switch, ensuring that client traffic can continue to be routed without disruption.

For configuring wireless access for multiple classes of IoT devices with varying security requirements, using a single SSID with Multiple Pre-Shared Keys (MPSK) is an efficient solution. MPSK allows different devices or groups of devices to connect to the same SSID but with unique PSKs, facilitating unique security policies for each class. Given that some IoT devices only support 802.11b, which operates in the 2.4GHz band, it is essential to include the 2.4GHz band in the configuration. The 5GHz band should also be included to support devices capable of operating in that band and to optimize network performance. The 6GHz band (option A) is not suitable since 802.11b devices are not compatible with it. Individual SSIDs for each IoT class (options C and D) would unnecessarily complicate network management and SSID overhead.