How Is the CC-NUMA Home-Based Cache Coherency Protocol Implemented When

Multiple Choice

How is the CC-NUMA home-based cache coherency protocol implemented when a cache miss occurs on a read?

A) The reading node contacts the home node, which always stores the most updated version of the data item. The home node forwards the data to the requesting node.
B) The reading node contacts the home node. If the data item is clean, the home node forwards it to the reading node. If the data item is dirty, the home node forwards the request to the node with the dirty copy. This node sends the data to both the home node and the requesting node.
C) The reading node contacts the home node. If the data item is clean, the home node forwards it to the reading node. If the data item is dirty, the home node broadcasts a request for the dirty copy to all nodes. The node with the dirty copy sends the data to both the home node and the requesting node.
D) The reading node contacts the home node. If the data item is clean, the home node forwards it to the reading node. If the data item is dirty, the home node broadcasts a request for the dirty copy to all nodes. The node with the dirty copy sends the data to the home node, which forwards it to the requesting node.