The cable test for PC2 indicates an open circuit on pin 3. This means there is a break in the physical continuity of that specific wire within the cable or a bad connection at the connector. An open circuit prevents the electrical signals from traversing the full length of the wire, leading to a complete loss of connectivity. Replacing the faulty patch cable with a known good one is the most direct solution.

 The test result for PC4 shows it is assigned to VLAN 11, while all other devices intended for communication on that subnet are on VLAN 10. Virtual LANs (VLANs) segment a physical network into separate logical broadcast domains. Devices in different VLANs cannot communicate directly at Layer 2. To resolve this logical connectivity issue, the switch port connected to PC4 must be reconfigured from VLAN 11 to VLAN 10.

The cable test for PC5 reveals a miswired cable with an incorrect pin-out. The diagram shows that the wire pairs are not mapped correctly according to the T568A or T568B wiring standards (e.g., it appears to have split pairs). This physical layer fault disrupts the differential signaling used by Ethernet, leading to excessive crosstalk and preventing a stable network link, especially at Gigabit speeds. The cable must be re-terminated correctly or, more simply, replaced.

For VLANs: Cisco Systems, Inc. (2022). Catalyst 9300 Series Switches, Cisco IOS XE Amsterdam 17.3.x (Catalyst 9300 Switches) - VLANs. "VLANs provide a mechanism to partition a physical network into smaller, logical broadcast domains. [...] Traffic between different VLANs must be routed through a Layer 3 device." This supports the diagnosis that PC4's placement in VLAN 11 isolates it from devices in VLAN 10.

For Cable Faults (Open/Short, Pin-out): Kurose, J. F., & Ross, K. W. (2021). Computer Networking: A Top-Down Approach (8th ed.). Pearson. In Chapter 5, the text discusses the physical layer and the importance of correct wiring for twisted-pair copper cables to mitigate electrical interference and ensure signal integrity. A miswired cable (incorrect pin-out) or a broken wire (open circuit) directly violates these physical layer requirements, leading to connection failure.

For Wiring Standards: Telecommunications Industry Association. (2018). ANSI/TIA-568.2-D: Balanced Twisted-Pair Telecommunications Cabling and Components Standard. This standard specifies the pin-pair assignments for T568A and T568B wiring schemes. The diagrams for PC5 clearly show a deviation from these standards, confirming an "Incorrect pin-out." The standard also defines continuity testing, where a failure (like the open on PC2) indicates a non-compliant cable.