Network Troubleshooting practice questions

The access point in the break room is overheating.

Why wrong: Incorrect; overheating would affect all nearby users, not just the break room.

Users in the break room are connecting to a 5 GHz network with poor range.

Why wrong: Incorrect; 5 GHz has shorter range, but the break room is likely close to an AP.

The break room has too many walls blocking the signal.

Why wrong: Incorrect; the scenario says offices nearby have excellent speeds, so signal strength is not the issue.

The web server's firewall is blocking ICMP.

Why wrong: Incorrect; ICMP is used by ping, and ping to IP works, so ICMP is not blocked.

The DHCP server is not assigning correct IP addresses.

Why wrong: Incorrect; internet access works, so DHCP is fine.

The network switch is dropping packets to the server.

Why wrong: Incorrect; if the switch were dropping packets, pinging the IP would also fail.

Replace the Wi-Fi adapter.

Why wrong: Incorrect; the adapter is recognized and enabled, so hardware failure is unlikely.

Reset the network switch.

Why wrong: Incorrect; other devices work, so the network infrastructure is fine.

Disable the Windows Firewall.

Why wrong: Incorrect; firewall issues would not prevent obtaining an IP address.

The PC's IP configuration.

Why wrong: Incorrect; the PC might have a valid IP, but the physical link is missing.

The VoIP phone's firmware version.

Why wrong: Incorrect; firmware issues would likely affect the phone itself.

The switch port the phone is connected to.

Why wrong: Incorrect; the phone works, so the switch port is fine.

The access point is using a non-overlapping channel.

Why wrong: Incorrect; non-overlapping channels are good and would not cause selective connectivity.

The devices have incorrect SSID credentials.

Why wrong: Incorrect; credentials would affect all devices, not just some.

The access point is overloaded with clients.

Why wrong: Incorrect; overload would affect all clients, not just some.

The remote site's DNS server is down.

Why wrong: Incorrect; DNS issues would affect name resolution, not connectivity to internet IPs.

The remote site's firewall is blocking port 443.

Why wrong: Incorrect; port 443 is for HTTPS, but internal servers work, so firewall isn't blocking all traffic.

The VPN encryption algorithm is mismatched.

Why wrong: Incorrect; a mismatch would prevent the VPN from establishing entirely.

The file server is powered off.

Why wrong: Incorrect because other devices can access the shares, so the server is on.

The Wi-Fi router is overloaded.

Why wrong: Incorrect because other devices work fine, and internet access works.

The laptop's firewall is blocking all traffic.

Why wrong: Incorrect because internet access works; a full block would prevent all connectivity.

Port 4 is administratively disabled.

Why wrong: Incorrect; the LED is solid green, indicating the port is active.

The cable on port 4 is faulty.

Why wrong: Incorrect; a faulty cable would cause no link or errors, but users communicate locally.

The router's DHCP pool is exhausted.

Why wrong: Incorrect; users can communicate locally, so they have IP addresses.

The printer is using too much bandwidth.

Why wrong: Incorrect; printers use minimal network bandwidth, and this is a wired desktop scenario.

The desktop has a duplicate IP address.

Why wrong: Incorrect; duplicate IP would cause constant issues, not only when printing.

The switch port is administratively down.

Why wrong: Incorrect; that would cause permanent loss, not intermittent.

The camera's IP address is conflicting with another device.

Why wrong: Incorrect; an IP conflict would not cause the switch port LED to be off.

The PoE switch does not support the camera's power requirement.

Why wrong: Incorrect; the port LED would likely be on if power were the only issue, but no link indicates signal problem.

The camera is configured for a different VLAN.

Why wrong: Incorrect; VLAN misconfiguration would not cause the physical link LED to be off.

Increase the transmit power of the access point.

Why wrong: Higher power can cause more interference with neighboring networks and may not solve the congestion issue; it can even make it worse.

Disable SSID broadcast to hide the network.

Why wrong: Hiding the SSID does not reduce interference or channel congestion; it only makes the network less visible to clients.

Replace the access point with a higher-gain antenna model.

Why wrong: Higher-gain antennas may extend range but do not address channel congestion; they could even increase interference with other networks.

The switch port is set to half-duplex.

Why wrong: Half-duplex could cause collisions and poor performance, but the intermittent nature and shared port suggest congestion rather than duplex mismatch.

The network cable is too long.

Why wrong: Excessive cable length can cause signal degradation, but this would likely cause constant issues, not intermittent drops.

The phone’s firmware is outdated.

Why wrong: Outdated firmware might cause bugs, but the scenario points to a network resource contention issue, which is best addressed by QoS.

Replace the Wi-Fi adapter.

Why wrong: The adapter works since the laptop has an IP and can ping the gateway, so replacing it is premature.

Verify the SSID is correct.

Why wrong: The laptop is connected to the network with a strong signal, so the SSID is already correct.

Disable the firewall temporarily.

Why wrong: Firewalls typically block specific traffic, but since the gateway ping works, the firewall is not blocking all traffic; DNS is a more targeted check.

The computer has a valid static IP address.

Why wrong: A static IP would not be in the APIPA range unless manually set, which is unlikely; 169.254.x.x is reserved for APIPA.

The DNS server is not responding.

Why wrong: DNS failure would show a valid IP but no name resolution; the 169.254 address indicates a DHCP failure, not DNS.

The network cable is unplugged.

Why wrong: If the cable were unplugged, the computer would have no IP at all or a disconnected status, not an APIPA address.

The printer’s IP address has changed.

Why wrong: If the IP changed, the ping would fail because the technician pinged the old IP; the ping succeeded, so the IP is correct.

The printer is not set as the default printer.

Why wrong: Not being default would not prevent connection; the user can still select and print to it manually.

The network switch port for the printer is disabled.

Why wrong: If the switch port were disabled, the ping would fail because the printer would be unreachable.

The DHCP server is out of IP addresses.

Why wrong: If DHCP were exhausted, Ethernet would also fail, but the user can connect via Ethernet.

The wireless adapter driver is corrupted.

Why wrong: A corrupted driver would likely prevent the adapter from seeing networks at all, but the user sees available networks.

The router’s SSID is hidden.

Why wrong: A hidden SSID would prevent the network from appearing in the list, but the user sees available networks.

The switch has a bad port.

Why wrong: A bad port would affect only one user, not multiple users simultaneously, and local communication would also fail for that user.

The DNS server is unreachable.

Why wrong: DNS failure would prevent name resolution but users could still access the internet by IP address; the scenario says no internet access at all.

The workstations have incorrect subnet masks.

Why wrong: Incorrect subnet masks would likely disrupt local communication as well, but users can still communicate locally.

Replace the network cable.

Why wrong: While a bad cable could cause this, it is better to first verify the cable and port status before replacing components.

Restart the DHCP service on the router.

Why wrong: Restarting DHCP would affect all devices, not just one, so it is not the appropriate first step for a single workstation issue.

Assign a static IP address to the workstation.

Why wrong: Assigning a static IP bypasses DHCP but does not identify the root cause; troubleshooting should start at the physical layer.

The server’s default gateway is incorrect.

Why wrong: An incorrect gateway would prevent the server from reaching the internet, but internal access works, so the gateway is likely correct.

A firewall rule on the server is blocking inbound traffic.

Why wrong: This could block internet access, but the scenario points to a network-level issue since internal access works; port forwarding is the common missing piece.

The DNS A record for the server points to the wrong IP.

Why wrong: A wrong DNS record would cause name resolution failure, but the scenario says the server is not accessible from the internet, which could be due to missing port forwarding regardless of DNS.

Replace the entire fiber cable.

Why wrong: Replacing the cable is a last resort after verifying signal levels and other components; it is too drastic at this stage.

Swap the SFP modules on both ends.

Why wrong: Swapping SFPs is a valid step, but checking signal level first is more systematic to isolate the problem to the cable or the transceivers.

Run a loopback test on the switch ports.

Why wrong: A loopback test checks the switch port itself, but the issue is on the fiber link between buildings, not the port.