MongoDB introduced a killCursors command in 3.2 to go along with the find and getMore commands. The .NET driver, however, doesn't use it, as there were no ill effects of not using it. However, Atlas free tier handles only the killCursors command and ignores OP_KILL_CURSORS. Given this limitation, and the possibility that the server will ultimately deprecate OP_KILL_CURSORS, the .NET driver should use the killCursors command with server versions >= 3.2.