220-1101 Network Troubleshooting — 15 Questions

Question 1

During a site survey, a technician finds that users in the break room experience very slow Wi-Fi while those in offices nearby have excellent speeds. What is the most likely cause?

Accepted Answer

A microwave oven in the break room is causing interference.. This scenario tests knowledge of wireless interference sources. Microwaves operate at 2.4 GHz, which is the same frequency band used by many Wi-Fi networks, causing significant interference and performance degradation.

Answer

The access point in the break room is overheating.

Answer

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

Answer

The break room has too many walls blocking the signal.

Question 2

A technician is troubleshooting a network where users can access the internet but cannot reach a specific internal web server by its hostname. Pinging the server's IP address works. What is the most likely issue?

Accepted Answer

The DNS server does not have a record for the server's hostname.. This question tests DNS resolution. If the IP works but the hostname does not, the problem is with DNS—either the server's A record is missing or the DNS server is not responding for that zone.

Answer

The web server's firewall is blocking ICMP.

Answer

The DHCP server is not assigning correct IP addresses.

Answer

The network switch is dropping packets to the server.

Question 3

A user's laptop cannot connect to any network after a recent OS update. The Wi-Fi adapter shows as enabled in Device Manager with no errors, and other devices on the same network work fine. What should the technician do first?

Accepted Answer

Run ipconfig to check the IP address.. This question tests systematic troubleshooting. Since the hardware appears fine and other devices work, the issue is likely software-related. Checking IP configuration with ipconfig is the logical first step to see if the adapter has a valid IP or is stuck with an APIPA address.

Answer

Replace the Wi-Fi adapter.

Answer

Reset the network switch.

Answer

Disable the Windows Firewall.

Question 4

A user reports that their VoIP phone works but the PC connected to the phone's passthrough port has no network access. What should the technician check first?

Accepted Answer

The Ethernet cable between the phone and the PC.. This question tests understanding of VoIP passthrough ports. The PC's lack of connectivity is often due to a faulty or unseated Ethernet cable between the phone and PC. The phone itself is working, so the upstream connection is fine.

Answer

The PC's IP configuration.

Answer

The VoIP phone's firmware version.

Answer

The switch port the phone is connected to.

Question 5

After deploying a new 802.11ac access point, users report that some devices can connect but others cannot, even though they are in the same room. All devices support 5 GHz. What is the most likely cause?

Accepted Answer

The access point has 2.4 GHz radios disabled.. This scenario tests knowledge of wireless standards and band compatibility. 802.11ac operates only on 5 GHz. If the access point is configured to use only 5 GHz, older devices that only support 2.4 GHz will not connect, but 5 GHz-capable devices will.

Answer

The access point is using a non-overlapping channel.

Answer

The devices have incorrect SSID credentials.

Answer

The access point is overloaded with clients.

Question 6

A company's remote site connects to the main office via a site-to-site VPN. Recently, users at the remote site report that they can access internal servers at the main office but cannot reach the internet. The main office users have full internet access. What is the most likely cause?

Accepted Answer

The VPN is configured as a full tunnel and the main office's internet link is down.. This question tests advanced routing and VPN concepts. A split-tunnel configuration allows remote traffic to go directly to the internet, while a full-tunnel sends all traffic through the VPN. If the VPN is full-tunnel and the main office's internet gateway is misconfigured or down, remote users lose internet access.

Answer

The remote site's DNS server is down.

Answer

The remote site's firewall is blocking port 443.

Answer

The VPN encryption algorithm is mismatched.

Question 7

A customer reports that their laptop can connect to the internet via Wi-Fi but cannot access any network shares on the local file server. Other devices on the same network can access the shares. What is the most likely cause?

Accepted Answer

The laptop has a misconfigured subnet mask.. This scenario tests understanding of network segmentation and IP addressing. The laptop can reach the internet (default gateway works) but not local resources, indicating a subnet mask or VLAN mismatch. The most common cause is an incorrect subnet mask, which prevents the laptop from recognizing the file server as local.

Answer

The file server is powered off.

Answer

The Wi-Fi router is overloaded.

Answer

The laptop's firewall is blocking all traffic.

Question 8

A small office uses a single router with four switch ports. Users on port 4 cannot access the internet, but they can communicate with each other. Port 4's LED is solid green. What is the most likely cause?

Accepted Answer

Port 4 is assigned to a different VLAN without internet access.. This scenario tests understanding of VLANs and router configuration. Inter-VLAN routing is required for different VLANs to reach the internet. If port 4 is on a different VLAN without a route to the internet, users can talk locally but not externally.

Answer

Port 4 is administratively disabled.

Answer

The cable on port 4 is faulty.

Answer

The router's DHCP pool is exhausted.

Question 9

A user complains that their desktop PC loses network connectivity intermittently, especially when the printer on the same desk starts printing. What is the most likely cause?

Accepted Answer

The network cable is run too close to power cables.. This question focuses on physical layer interference. Intermittent connectivity linked to a device starting suggests electromagnetic interference (EMI) from the printer's motor or power supply. Network cables near strong EMI sources can experience packet loss or disconnects.

Answer

The printer is using too much bandwidth.

Answer

The desktop has a duplicate IP address.

Answer

The switch port is administratively down.

Question 10

A technician is called to a warehouse where a newly installed IP camera shows 'No Signal' on the NVR. The camera is connected via a 100-meter Cat6 cable to a PoE switch. The switch port LED is off. What is the most likely cause?

Accepted Answer

The cable length exceeds the maximum specification for Ethernet.. This question tests knowledge of Ethernet cable length limits. Cat6 is rated for 100 meters; at exactly that distance, signal degradation can cause link failure. The PoE switch may not provide enough power over that distance, or the cable may be slightly too long.

Answer

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

Answer

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

Answer

The camera is configured for a different VLAN.

Question 11

A technician is setting up a new wireless network in a crowded office building. Users report that their laptops frequently disconnect from the Wi-Fi and have slow speeds, even when close to the access point. The technician scans the area and sees many overlapping Wi-Fi networks. What is the best solution to improve performance?

Accepted Answer

Change the access point to a less congested channel.. In a dense environment with many overlapping networks, channel congestion is a major cause of interference and disconnections. Changing the access point to a less congested channel reduces co-channel interference and improves stability and throughput.

Answer

Increase the transmit power of the access point.

Answer

Disable SSID broadcast to hide the network.

Answer

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

Question 12

A customer complains that their VoIP phone intermittently drops calls and has poor audio quality. The phone is connected to a switch port that also carries data traffic for a nearby workstation. What is the most likely cause?

Accepted Answer

Quality of Service (QoS) is not configured on the switch port.. VoIP is sensitive to latency and packet loss. When a switch port carries both voice and data without proper QoS, data traffic can congest the link, causing dropped packets and poor audio. QoS prioritizes voice traffic to prevent this.

Answer

The switch port is set to half-duplex.

Answer

The network cable is too long.

Answer

The phone’s firmware is outdated.

Question 13

A user’s laptop is connected to a Wi-Fi network with a strong signal, but the user cannot access any network resources. The IP configuration shows an address of 192.168.1.50 with a subnet mask of 255.255.255.0 and a default gateway of 192.168.1.1. The technician pings the gateway successfully. What should the technician check next?

Accepted Answer

Check the DNS server settings on the laptop.. Since the gateway is reachable, the issue is likely beyond the local network. DNS is the most common cause of being unable to access resources by name when basic connectivity exists. Checking DNS resolution is the logical next step.

Answer

Replace the Wi-Fi adapter.

Answer

Verify the SSID is correct.

Answer

Disable the firewall temporarily.

Question 14

A user reports that their computer is connected to the network but cannot access any websites. The technician checks the IP configuration and sees an IP address of 169.254.1.5. What does this indicate?

Accepted Answer

The DHCP server is unavailable or the computer cannot reach it.. An IP address in the 169.254.x.x range is an Automatic Private IP Addressing (APIPA) address, assigned when a DHCP server is unreachable. This means the computer failed to get a valid IP from DHCP, so it cannot communicate beyond the local link.

Answer

The computer has a valid static IP address.

Answer

The DNS server is not responding.

Answer

The network cable is unplugged.

Question 15

A user reports that their computer can access the internet but cannot connect to a network printer that is on the same subnet. The technician pings the printer’s IP address from the computer and gets a reply. What is the most likely cause?

Accepted Answer

The printer’s print queue is paused or the printer is offline.. Since the ping succeeds, the printer is reachable at the network level. The issue is likely with the printer configuration or the print spooler on the computer. Common causes include the printer being offline, paused, or having a driver issue.

Answer

The printer’s IP address has changed.

Answer

The printer is not set as the default printer.

Answer

The network switch port for the printer is disabled.