Cisco CCNA (200-301)Network FundamentalsMedium
A network administrator is performing maintenance on a Cisco switch. They need to configure a specific port to always operate at 100 Mbps full duplex, regardless of the connected device's auto-negotiation capabilities. Which set of commands would achieve this on a GigabitEthernet0/1 interface?
- Ainterface GigabitEthernet0/1 negotiation auto
- Binterface GigabitEthernet0/1 speed 100 duplex full
- Cinterface GigabitEthernet0/1 speed auto duplex auto
- Dinterface GigabitEthernet0/1 media-type rj45
Show answer & explanationAnswer & explanation
Correct answer: B. interface GigabitEthernet0/1 speed 100 duplex full
To manually set the speed and duplex of an interface, the 'speed' and 'duplex' commands are used. Setting 'speed 100' and 'duplex full' explicitly configures the port to the desired 100 Mbps full-duplex operation, overriding auto-negotiation.
Why the other options are wrong
- A. 'negotiation auto' is related to auto-negotiation, not manual speed/duplex setting, and might not be a valid standalone command depending on IOS version.
- C. This configures auto-negotiation for both speed and duplex, which is the opposite of the requirement.
- D. 'media-type rj45' specifies the connector type, which is irrelevant to speed and duplex settings.
Cisco IOS Interface Speed/Duplex
Cisco IOS allows manual configuration of interface speed and duplex settings, overriding auto-negotiation, using the 'speed' and 'duplex' commands.
- Manual settings are useful to resolve auto-negotiation issues or enforce specific link parameters.
- If one side is manually configured and the other is auto-negotiating, a duplex mismatch can occur.
- Common speed options include 10, 100, 1000, and auto. Duplex options are half, full, and auto.
Memory trick: Speed and Duplex are set explicitly, Auto-Negotiate is for flexibility.