Troubleshooting Scenario Questions

The charging port is loose.

Why wrong: A loose port would cause intermittent charging or no power at all, not a consistent 'not charging' status.

The power management driver is outdated.

Why wrong: Driver issues can cause charging problems, but a hardware failure is more likely given the battery's age and symptoms.

The CMOS battery is dead.

Why wrong: A dead CMOS battery affects system clock and BIOS settings, not main battery charging.

The fan is running at low speed due to a faulty fan controller.

Why wrong: The fan is spinning, so the controller is likely fine; the issue is thermal transfer, not fan speed.

The CPU is faulty and needs replacement.

Why wrong: A faulty CPU is possible but less likely than a thermal paste issue; overheating is a common symptom of poor thermal contact.

The BIOS is set to an aggressive power-saving mode.

Why wrong: Power-saving modes reduce performance, not cause overheating; they would lower temperatures.

Replace the entire keyboard assembly.

Why wrong: The keyboard is separate from the touchpad; replacing it won't fix touchpad issues.

Replace the laptop's LCD screen.

Why wrong: The LCD screen has no relation to touchpad input.

Reinstall the operating system.

Why wrong: Driver update already done; reinstalling OS is excessive and unlikely to fix a hardware connection issue.

The phone's battery level

Why wrong: Battery level does not affect NFC functionality as long as the phone is on.

The payment terminal's internet connection

Why wrong: NFC transactions can work offline; the terminal's internet is for authorization, not detection.

The phone's default payment app settings

Why wrong: App settings affect which card is used, but the terminal not detecting the phone at all points to a hardware or alignment issue.

Ensure the tablet's Bluetooth is turned on.

Why wrong: The tablet already connects to headphones, so Bluetooth is on. This is not the issue.

Update the tablet's operating system.

Why wrong: An OS update is unlikely to fix a specific pairing issue with one device, especially when other Bluetooth devices work.

Reset the tablet's network settings.

Why wrong: Resetting network settings is a more drastic step and should be done after simpler checks, like ensuring the keyboard is in pairing mode.

Check the device's MAC address filter on the router.

Why wrong: MAC filtering would block the device from connecting to specific networks, but the scenario says it cannot connect to any Wi-Fi network, not just one.

Check if the device's date and time are correct.

Why wrong: Incorrect date/time can cause SSL errors but typically does not prevent initial Wi-Fi association.

Check if the device's Bluetooth is interfering.

Why wrong: Bluetooth and Wi-Fi can interfere on the 2.4 GHz band, but this would cause intermittent issues, not a complete inability to connect to any network.

The internal storage is full and cannot accept new data.

Why wrong: If storage were full, the app would likely fail to read or write, and the scenario says reading works.

The app's cache needs to be cleared to free up space.

Why wrong: Clearing cache might help with performance but does not address API-level storage restrictions.

The device's SD card has been removed.

Why wrong: The scenario mentions internal storage, not external SD card, so this is irrelevant.

FTP

Why wrong: FTP is for file transfers, not for forwarding web requests from a proxy.

DNS

Why wrong: DNS resolves names, but the proxy uses it separately; the forwarding protocol is HTTP/HTTPS.

SNMP

Why wrong: SNMP is for network management, not for forwarding web traffic.

SIP: 80, RTP: 443

Why wrong: Ports 80 and 443 are for HTTP/HTTPS, not VoIP.

SIP: 1720, RTP: 5060

Why wrong: Port 1720 is for H.323, and RTP does not use 5060.

SIP: 443, RTP: 80

Why wrong: These ports are for web traffic, not VoIP.

The fiber cable is damaged

Why wrong: A damaged cable would cause the port to show 'down' or 'notconnect', not 'err-disabled', which is a software-disabled state.

A duplex mismatch exists between the switches

Why wrong: Duplex mismatch causes high error rates and poor performance but typically results in 'down' or 'flapping' ports, not 'err-disabled'.

The VLAN configuration is incorrect

Why wrong: Incorrect VLAN config would allow the port to be up but traffic may not pass; it would not cause err-disabled state.

A hub

Why wrong: A hub is a Layer 1 device that cannot route between VLANs.

A Layer 2 switch

Why wrong: A Layer 2 switch can create VLANs but cannot route between them without a router.

A bridge

Why wrong: A bridge connects two network segments but does not route between VLANs; it is a Layer 2 device.

The modem is defective.

Why wrong: A defective modem would typically not sync at all or would drop sync, not sync at a lower speed consistently.

The router's firmware needs updating.

Why wrong: Firmware updates affect features and security, not the physical sync speed determined by line quality and distance.

The ISP is throttling the connection.

Why wrong: Throttling would reduce throughput after sync, but the sync rate itself is a physical layer characteristic.

tracert

Why wrong: Tracert shows the route and per-hop delays but is not the primary tool for simple reachability and round-trip time.

nslookup

Why wrong: Nslookup resolves domain names to IP addresses but does not test connectivity.

netstat

Why wrong: Netstat displays active connections and listening ports, not reachability or latency.

The cable is only Cat5 and cannot support Gigabit.

Why wrong: While Cat5 may not support Gigabit, the issue is a physical break, not a category limitation.

The cable has a short circuit between pins 4 and 5.

Why wrong: A short would show continuity, not an open circuit; the tester shows no continuity, indicating a break.

The wall jack is wired for T568A but the patch panel is T568B.

Why wrong: Mismatched standards would cause a crossover, not an open circuit on specific pins.

The crossover cable will prevent any network connectivity.

Why wrong: Auto-MDIX on modern switches allows crossover cables to function normally, so this is not necessarily true.

The crossover cable will cause intermittent connectivity.

Why wrong: Intermittent issues are not typical of a crossover cable; it either works or doesn't.

The crossover cable will only work at 100 Mbps.

Why wrong: Crossover cables can support Gigabit speeds if properly constructed.