フリー問題

問題文

Three servers form a cluster. One of them becomes the active node. What role do the other two play when a client request arrives at one of them?

選択肢

1. They each hold an independent copy of the data and answer from that copy, with the active node reconciling the copies in the background so that the cluster can keep serving requests if any one node is lost.
2. They stay sealed until the active node fails, so a request that reaches them is refused with a sealed error.
3. They either forward the request to the active node or redirect the client to it, depending on the configuration and the request's headers.
4. They serve read requests locally and forward only writes, which is how the cluster spreads the read load.