A network administrator set up a network computer lab and discovered connectivity issues. The administrator is able to ping the fiber uplink interface, but none of the new PCs plugged into the switch respond to ICMP requests. Which of the following should the administrator perform FIRST?
A. Check if there are link lights on the ports
B. Checkthe ports on the switch for full duplex
C. Check to see if port security is enabled
D. Check to see if the uplink interface is configured correctly.