A security engineer is trying to connect cameras to a 12-port PoE switch, but only...

The most likely reason why only eight cameras turn on is that the PoE switch does not have enough power budget to supply all 12 cameras. The engineer should check the voltage and wattage ratings of the PoE switch and the cameras, and make sure they are compatible and sufficient. The Ethernet cable type, transceiver compatibility, and DHCP addressing are less likely to cause this problem, as they would affect the data transmission rather than the power delivery.

References:

CompTIA Network+ N10-008 Certification Study Guide, page 181

CompTIA Network+ N10-008 Cert Guide, Deluxe Edition, page 352

PoE Troubleshooting: The Common PoE Errors and Solutions3