When the Inter-Switch Link (ISL) is down but the keepalive link is still operational, both VSX switches detect each other as active and continue to forward traffic independently. This prevents a split-brain scenario because the keepalive link ensures both nodes are aware of each other's status.

OSPF (Open Shortest Path First) is a routing protocol that uses link-state information to calculate the best path to each destination in the network. OSPF establishes adjacencies with neighboring routers to exchange routing information and maintain a consistent view of the network topology1.
To establish an OSPF adjacency, the routers need to have some common parameters, such as the area ID, the network type, the hello interval, the dead interval, and the authentication method2. The routers also need to have a matching subnet mask on the interface that connects them3.
In this case, the Aruba CX 6300 VSF stack has an SVI (Switched Virtual Interface) on VLAN 10 with an IP address of 10.1.1.1/24 and a LAG (Link Aggregation Group) on port 1/1/1 and port 2/1/1 that connects to a neighboring device. The SVI is configured with OSPF area 0 and network type broadcast. The LAG is configured with OSPF passive mode, which means that it will not send or receive OSPF hello packets.
The neighboring device has an interface with an IP address of 10.1.1.2/24 and a LAG on port 1/0/1 and port 2/0/1 that connects to the Aruba CX 6300 VSF stack. The interface is configured with OSPF area 0 and network type broadcast.
Since the Aruba CX 6300 VSF stack and the neighboring device have the same area ID, network type, subnet mask, and default hello and dead intervals on their interfaces, they will be able to establish an OSPF adjacency over SVI 10 with LAG 1. The OSPF passive mode on the LAG will not affect the adjacency, because it only applies to the LAG interface, not the SVI interface.

Multi-Domain Authentication allows a CX switch port to support authentication for both a computer and a VoIP phone simultaneously. This ensures each device type (data and voice) can be authenticated and assigned to the appropriate VLAN, meeting the requirement for authenticating a single computer connected through a VoIP phone.

Strict queuing is the best scheduling technology to use for voice traffic on an AOS-CX switch.
Scheduling is a mechanism that determines how packets are transmitted from different queues on an egress port. Strict queuing is a scheduling method that gives the highest priority queue absolute preference over all other queues, regardless of their size or utilization. Voice traffic should be assigned to the highest priority queue and scheduled with strict queuing to ensure minimal latency and jitter. The other options are incorrect because they are either not scheduling methods or not optimal for voice traffic.