A+ Question of the Week: Ethernet Switches

AplusQOW1You have connected two Ethernet switches to one another. The port used on one switch has an illuminated link light, but the link light on the other switch is not lit. Which of the following is the most likely cause?

    1. One or both of the switches are defective
    2. The cable used to interconnect the switches is faulty
    3. The switches are not running the same protocol
    4. One of the switches does not have an IP address assigned

The correct answer is 2.

Link lights illuminate when an interface detects a link pulse compatible with the link pulse it sends out. If a cable between two devices is asymmetrical, in that one pair can transmit a signal, but the other pair cannot, the device with the functioning receive pair will have an illuminated link light triggered by the link pulse received from the other device, while the device with the nonfunctioning receive pair will not.

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