I tested with 5 servers, 3 config servers, 5 shard servers. I used mongo route server(mongos) to visit the data. I found that when shut down the first config server's network which configured in mongos config file(such as shutdown switch port, ifconfig down server network card, turn off the computer), we can't visit the data well, it's very slow, always it will be cost several minutes.In this situation, the high availability is not good, even has not high availability.