Hard Difficulty Questions

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 LCD screen assembly.

Why wrong: The tablet does not power on at all (no vibration, no sound), not just a black screen. The LCD is not the cause of a complete power failure.

Replace the motherboard.

Why wrong: Motherboard failure is possible but less likely than a simple connection issue. The technician should check simpler components first.

Perform a hard reset by holding the power and volume buttons for 30 seconds.

Why wrong: A hard reset is a software troubleshooting step, but the technician has already confirmed the battery is charged and the button feels normal. The issue is likely hardware, not software.

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.

Uninstall the mouse driver and reboot.

Why wrong: This would remove the mouse driver entirely, requiring reinstallation and potentially affecting other devices.

Change the mouse's Bluetooth pairing to a different channel.

Why wrong: Bluetooth channels are managed automatically; manual channel selection is not a standard user setting.

Update the laptop's BIOS to the latest version.

Why wrong: BIOS updates can fix hardware compatibility, but this is a driver/software issue, not a BIOS problem.

The phone's battery management system is faulty.

Why wrong: A faulty battery management system could cause overheating, but the pad working with another phone points to an external factor like the case.

The phone's wireless charging coil is misaligned with the pad.

Why wrong: Misalignment would prevent charging from the start, not after a few minutes.

The wireless charging pad is not Qi-certified.

Why wrong: If the pad works with another phone, certification is not the issue; the problem is specific to this phone.

The laptop's graphics card cannot drive two 4K monitors.

Why wrong: If the laptop supports Thunderbolt 3, it likely has a capable GPU, but the issue is with the hub, not the laptop.

The monitors are not compatible with USB-C.

Why wrong: Monitors with DisplayPort or HDMI can be adapted, but the hub's limitation is the bottleneck.

The user needs a USB-C to HDMI adapter for each monitor.

Why wrong: Adapters would not solve the bandwidth issue; a Thunderbolt 3 dock is necessary.

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 smartphone's battery saver mode is limiting hotspot performance.

Why wrong: Battery saver may reduce performance but typically does not cut off data entirely after a few minutes.

The laptop's Wi-Fi adapter is overheating.

Why wrong: Overheating would cause the laptop's Wi-Fi to disconnect, but the scenario says the hotspot remains enabled and the smartphone still has data.

The smartphone is switching to a different cellular band.

Why wrong: Band switching can cause a brief interruption, but the hotspot would typically reconnect quickly, not remain inactive for minutes.

The tablet's Wi-Fi is interfering with the LTE signal.

Why wrong: Wi-Fi and LTE operate on different frequencies and bands; interference is unlikely to cause slow speeds on one tablet.

The tablet's SIM card is not fully inserted.

Why wrong: A partially inserted SIM would likely cause no service or intermittent connection, not consistently slow speeds.

The tablet's battery saver mode is enabled.

Why wrong: Battery saver can reduce performance, but it typically affects CPU and background data, not LTE radio speed directly.

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.

DHCP

Why wrong: DHCP assigns IP addresses, but the issue is name resolution, not IP assignment.

IPsec

Why wrong: IPsec provides encryption for VPN traffic, not name resolution.

SSL/TLS

Why wrong: SSL/TLS provides encryption for VPN connections, not DNS configuration.

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.

1433

Why wrong: Port 1433 is used by Microsoft SQL Server, not MySQL.

1521

Why wrong: Port 1521 is used by Oracle Database, not MySQL.

5432

Why wrong: Port 5432 is used by PostgreSQL, not MySQL.

The server is running HTTPS on a non-standard port.

Why wrong: HTTPS typically uses port 443 or 8443, not 8080.

The server is running an FTP service.

Why wrong: FTP uses ports 20 and 21, not 8080.

The server is using a custom application protocol.

Why wrong: While possible, port 8080 is most commonly associated with HTTP alternatives, not custom protocols.

Increase the bandwidth of the internet connection

Why wrong: More bandwidth may help but does not guarantee voice quality; without QoS, voice packets still compete with data and may be dropped.

Change all VoIP phones to use static IP addresses

Why wrong: Static IPs do not affect call quality; they only prevent IP address changes. They do not address bandwidth contention.

Disable DHCP on the network to reduce broadcast traffic

Why wrong: Disabling DHCP would cause connectivity issues and not solve the voice quality problem; broadcasts are not the primary cause.

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.

Enable DHCP snooping on the guest VLAN

Why wrong: DHCP snooping prevents rogue DHCP servers but does not isolate traffic between VLANs; ACLs are needed for that.

Configure a router-on-a-stick with subinterfaces

Why wrong: This allows routing between VLANs, which is the opposite of isolation; without ACLs, it would actually enable communication.

Set the guest network to use a different subnet mask

Why wrong: Different subnet masks alone do not prevent routing; the router will still forward traffic unless explicitly blocked by ACLs.

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.

Omnidirectional antenna

Why wrong: Omnidirectional antennas radiate in all directions, but they are less effective in penetrating dense obstacles and may cause interference.

Dipole antenna

Why wrong: A dipole antenna is a type of omnidirectional antenna, which is not optimal for this environment.

Rubber duck antenna

Why wrong: A rubber duck antenna is a small omnidirectional antenna, unsuitable for penetrating metal and concrete.