The driver.BatchCursor type retains a reference to a driver.Server and uses driver.SingleServerDeployment to use it directly. There's no Cursors spec, but from speaking with engineers on other drivers, it seems that it's more robust to instead keep the address of the server on which the cursor exists and go through the full server selection process to find it, similar to what is done for session pinning. This ensures that we do not route getMore/killCursors commands to a server that has been marked Unknown.