Exam 300-715 topic 1 question 190 discussion

I think this should be B: https://www.ciscopress.com/articles/article.asp?p=2812072

It's about "Reachability" the ISE nodes have to reach eachother over TLS/SSL which requires PKI/Valid Certs.

The link provided by Kornalt is clear You can join more than one ISE node together to create a multinode deployment, known commonly in the field as an ISE cube. It is important to understand that before any ISE nodes can be joined together, they must trust each other’s administrative certificate. Without that trust, you will receive a communication error stating that the “node was unreachable,” but the root cause is the lack of trust. The answer is B but in this case the answer is pretty clear :)

out of experience - B

B- From the link kornalt supplied, it is clear.

The second node must be in standalone mode before joining it to the primary node.

Answer is Clearly B. You can join more than one ISE node together to create a multinode deployment, known commonly in the field as an ISE cube. It is important to understand that before any ISE nodes can be joined together, they must trust each other’s administrative certificate. Without that trust, you will receive a communication error stating that the “node was unreachable,” but the root cause is the lack of trust.