The reason is that ClearPass OnBoard is a tool that allows you to enroll Mac computers into a ClearPass Policy Manager site using an Apple MDM push certificate. This certificate can be obtained from Apple or from a third-party PKI provider.
Apple Configurator is a tool that allows you to configure and deploy Mac computers using a GPO. This tool can also be used to enroll Mac computers into a ClearPass Policy Manager site using an Apple MDM push certificate.

The active gateway feature is used to provide active-active layer 3 default gateway for hosts on the same subnet. It allows the switch to convert multicast streams into unicast streams over the wireless link, which improves the quality and reliability of streaming video, while preserving the bandwidth available to the non-video clients. The active gateway feature is unique to VSX configuration because it eliminates the need for VRRP and avoids traffic being pushed over the ISL link, which can cause latency in the network12.
The correct answer to the question is C. Sixteen different VMACs are supported for each IPv4 and IPv6 stack simultaneously. This means that you can have a maximum of eight VMACs for IPv4, and a maximum of eight VMACs for IPv6, on a VSX pair. Only 15 VMACs are supported on 6400 switch series2.
The other options are incorrect because:
A) Sixteen different VMACs are not supported total as shared. They are supported for each IPv4 and IPv6 stack separately.
B) Active gateway can be used without MSTP instances. MSTP is a protocol that allows multiple spanning tree instances to coexist on the same switch, but it does not affect how active gateway works.
D) Active gateway does not copy traffic over the ISL link for an optimized path. It avoids using the ISL link for routed traffic and uses the local switch interface MAC instead of the virtual MAC address (VMAC) for source address1.

Explanation:
According to the Aruba Documentation Portal1, the firewall role derivation flow in the correct order is:
* Server derived role
* User derived role
* Authentication default role
* Initiation role assigned

The reason is that PBR allows you to route packets based on policies that match certain criteria, such as source or destination IP addresses, ports, protocols, etc. PBR can also be used to set metrics, next-hop addresses, or tag traffic for different routes.