A network administrator is troubleshooting an issue with a newly deployed Power over Ethernet (PoE+) pan-tilt-zoom (PTZ) IP camera installed at the end of a 85-meter Category 6 UTP cable run. The camera initializes and streams video normally during daylight, but repeatedly reboots whenever its infrared (IR) illuminators turn on at night. A basic wiremapper confirms all eight conductors have pin-to-pin continuity and proper T568B pinout. Which TWO of the following physical layer causes or diagnostic approaches are most appropriate to identify and resolve this failure?
- Using a cable certifier capable of testing DC resistance unbalance across conductor pairs to check for high resistance in the cable run.Answer
- BUsing a tone generator and inductive probe set to pinpoint the distance to a suspected conductor split or break along the horizontal cabling.
- Verifying whether Copper-Clad Aluminum (CCA) cabling was installed instead of solid bare copper conductors for the long horizontal run.Answer
- DManually locking the switchport speed and duplex to 100Mbps full-duplex to eliminate auto-negotiation failures causing excessive frame check sequence (FCS) errors.
Answer
The correct approaches are using a cable certifier to test DC resistance unbalance and verifying that solid bare copper cabling was used instead of Copper-Clad Aluminum (CCA) wire.
The combination of daytime operation and nighttime reboots indicates that data transmission works fine, but power delivery fails when current demand increases. Cable certifiers that measure DC resistance unbalance evaluate the cable's electrical resistance under load, identifying high-resistance points. Furthermore, verifying that solid bare copper (rather than Copper-Clad Aluminum) was installed addresses the root cause, as CCA cabling exhibits much higher resistance, violating TIA standards and leading to significant voltage drops over long runs.
Step-by-Step Solution
Key Concept
DC Resistance and PoE Troubleshooting in Twisted-Pair Cabling
Estimated Time:1m 30s