CyberCertPrepNetwork FundamentalsNetwork DevicesEASYFree question
What is a rollover (console) cable used for, and why does it use a unique pin-out compared to a standard Ethernet cable?
- A.A rollover cable is used for Ethernet crossover connections between two switches when an auto-MDI-X switch is unavailable
- B.A rollover cable (also called a Cisco console cable) connects a PC's serial or USB port to a network device's RJ-45 console port for out-of-band CLI management; its pin-out reverses pins 1-8 to pins 8-1 (pin 1 to pin 8, pin 2 to pin 7, etc.) because the console port is DTE/DCE serial, not Ethernet
- C.A rollover cable is an older term for a Category 5e patch cable with a locking latch on the RJ-45 connector
- D.A rollover cable connects two routers back-to-back via their WAN interfaces for direct serial leased-line emulation
Why B is correct
A rollover (console) cable reverses all 8 wires (pin 1 to pin 8, pin 2 to pin 7, ...). It connects to the device's RJ-45 console port (which is a serial asynchronous port, not Ethernet) and to the PC via DB-9 serial or a USB-to-serial adapter. This is how network engineers access CLI management on Cisco, Juniper, and most network devices for initial configuration or recovery. It is not an Ethernet crossover cable and is not used for WAN serial connections.
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