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200-301 · Question #942

A client experiences slow throughput from a server that is directly connected to the core switch in a data center. A network engineer finds minimal latency on connections to the server, but data trans

The correct answer is A. a physical cable fault. An FCS error is a legal sized frame with a bad frame check sequence (CRC error). An FCS error can be caused by a duplex mismatch, faulty NIC or driver, cabling, hub, or induced noise. Sometimes FCS errors will increment when there is induced noise on the physical cable. Perform a

Submitted by layla.eg· Mar 5, 2026

Question

A client experiences slow throughput from a server that is directly connected to the core switch in a data center. A network engineer finds minimal latency on connections to the server, but data transfers are unreliable, and the output of the show interfaces counters errors command shows a high FCS-Err count on the interface that is connected to the server. What is the cause of the throughput issue?

Options

  • Aa physical cable fault
  • Ba speed mismatch
  • Chigh bandwidth usage
  • Da cable that is too long

How the community answered

(34 responses)
  • A
    59% (20)
  • B
    24% (8)
  • C
    12% (4)
  • D
    6% (2)

Explanation

An FCS error is a legal sized frame with a bad frame check sequence (CRC error). An FCS error can be caused by a duplex mismatch, faulty NIC or driver, cabling, hub, or induced noise. Sometimes FCS errors will increment when there is induced noise on the physical cable. Perform a cable test. Check the environment for electrical changes (industrial electrical motor turning on, EMI radiation, etc.). Make sure your physical wiring is safe from Electro-magnetic interference.

Topics

#FCS errors#cabling faults#network troubleshooting#Ethernet link issues

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