Final answer:
A Peer node status of 'Down' indicates that the peer node is not communicating with the master node, which may affect indexing and searching functions within an indexer cluster.
Step-by-step explanation:
When you see a Peer node status of "Down" in the MC > Indexer Clustering: Master Node panel, it signifies that the specific peer node is not currently communicating with the master node. This could be due to network issues, the peer node being shut down, or the Splunk service not running on that peer. The master node is responsible for managing the indexer cluster and ensuring that data is properly replicated and searchable. If a peer node is down, it means that it cannot participate in the indexing or searching functions within the cluster until the issue is resolved and the node's status returns to an active state.