A server directly connected to the core switch shows high FCS error counts and unreliable transfers. What is the likely cause?

A physical cable fault is the most likely cause of high FCS (Frame Check Sequence) error counts and unreliable transfers. FCS errors indicate data corruption during transmission, which often points to a damaged or faulty cable, poor crimps, or bad connectors. A speed mismatch would typically prevent the link from establishing or cause severe performance issues, but not necessarily high FCS errors. High bandwidth usage might lead to congestion and dropped packets, but not directly to FCS errors, as the frames themselves would generally be intact. A cable that is too long can cause signal attenuation and potentially lead to errors, but a direct connection to a core switch usually implies a shorter, controlled cable length where this is less probable than a physical fault.