The best answer for what type of port is sometimes used by routers for management and configuration purposes?
The answer is C: db9 port
In most routers, the console port is the port that is used to access your router’s console interface on your computer for configuration, administration and management purposes. To connect a router to a PC, you will need to use a rollover cable or a console. A rollover cable has a db9 connector on one end and an RJ 45 on the other end. Most computers these days do not have db9 (serial port connector). What you need is a USB to Serial converter. This cable will be connected to the computer via the db9 connector and then straight to the console port of the router.