Embodiments of the present application provide a monitoring server, a resolution server, a request device, and a node selection method. The monitoring server in the present application includes a receiver, a processor, and a transmitter. The receiver is configured to receive a selection request message sent by the resolution server; the processor is configured to generate a first source node suggestion table according to the selection request message and a source node selection table; and the transmitter is configured to send the first source node suggestion table to the resolution server, so that the resolution server generates a second source node suggestion table according to the first source node suggestion table and sends the second source node suggestion table to the request device, and the request device selects a source node according to the second source node suggestion table.