Two Nodes DFS-R take more than 10 seconds to switch when failover

I have deployed a 2 nodes (node A and B) DFS-R environment, and mapped the dfs shared folder to client X as a network disk. The properties of that network disk showed client X was connecting to node A. After I shutdown node A for testing, it took more than 10 seconds to get the network disk came to life. The properties of that network disk showed client X was connecting to client B. Is that normal? take more than 10 seconds to switch over. Because I think that is unacceptable for business.