C and E
If a Cisco switch port has only speed or duplex configured, the interface still uses auto-negotiation Fast Link Pulses (FLP) to negotiate the setting that was not configured. There is no explicit command to disable auto-negotiation.
B and C
Cisco switches disable auto-negotiation after the speed and duplex have been configured. The other switch attempts auto-negotiation and fails. However, the unconfigured switch can detect the speed even without auto-negotiation. By default, 10-Mbps and 100-Mbps ports use half duplex when they are unable to auto-negotiate a duplex setting.
C and D
The half-duplex switch leaves its loopback circuitry enabled, erroneously detecting ...