In InfiniBand networks, P_Keys (Partition Keys) control communication boundaries. Each port can belong to one or more partitions with either full or limited membership.

From NVIDIA InfiniBand Documentation (Partitioning and P_Keys):

"A limited (or partial) membership permits a port to communicate only with other ports in the same partition that have full membership. It cannot communicate with other limited members, even if they are in the same P_Key partition."

This makes limited/partial membership ideal for multi-tenant security , where tenant ports can reach infrastructure ports (full members) but not other tenant ports (limited members).

Incorrect Options:

A & B are not valid InfiniBand P_Key types.

C (Full membership) allows unrestricted communication within the same partition.