The Monitor class suppresses socket.timeout exceptions which causes the potentially dead host/server to stay in the topology description (see https://github.com/mongodb/mongo-python-driver/blob/3.8.0/pymongo/monitor.py#L141). As a result a server with sockets that are black-holed might be allowed to remain in the topology and cause applications to initiate operations on those black-holed sockets (see HELP-11666).