220-1101 Networking — 20 Questions

Question 1

A user reports that their desktop computer can access shared files on the local network but cannot reach the internet. The technician checks the IP configuration and sees the address 169.254.25.100 with a subnet mask of 255.255.0.0. Other computers on the same subnet can access the internet normally. Which of the following is the MOST likely cause?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Duplicate IP address on the network. The APIPA address 169.254.25.100 indicates the computer failed to obtain a DHCP lease. Since the user can still access local shared files, the physical layer (cable and NIC) is functional, ruling out option A. A duplicate IP address can cause Windows to release its lease and auto-assign an APIPA address to avoid the conflict. Local file access may still be possible if the conflicting device is not actively using the same IP at that moment. Options B and D would not result in an APIPA address.

Answer

Faulty Ethernet cable or network interface card (NIC)

Answer

Incorrect DNS server configuration

Answer

Firewall blocking internet access

Question 2

A technician sets up a small office network with a wireless router (with integrated DHCP) connected to an unmanaged 24-port switch. All desktop computers are connected to the switch via Ethernet cables. The computers can access the internet without issues, but they cannot ping each other by IP address. The technician checks one computer and sees an IP address of 192.168.1.10 with a subnet mask of 255.255.255.0, and can ping the router at 192.168.1.1. Which of the following is the MOST likely cause?

Accepted Answer

The computers' firewall software is blocking ICMP echo requests.. The computers are wired to the same switch and have valid IP configuration (192.168.1.10/24). They can reach the router and internet, but cannot ping each other. Client isolation (or AP isolation) is a wireless feature and does not apply to wired clients on the same Ethernet LAN. Unmanaged switches forward broadcasts, so ARP should work. The common reason for this symptom in a Windows environment is the Windows Firewall blocking ICMP echo requests by default.

Answer

The switch is not forwarding broadcast frames between ports.

Answer

The computers have an incorrect subnet mask configuration.

Answer

The DHCP server has run out of IP addresses.

Question 3

A network technician is troubleshooting a small office where several users cannot connect to the network. The DHCP server shows that the scope is 80% utilized. The technician checks the IP configuration of an affected computer and sees an IP address of 169.254.15.200 with a subnet mask of 255.255.0.0. Which of the following is the MOST likely cause of the issue?

Accepted Answer

The network cable is faulty or disconnected.. The IP address 169.254.15.200 is an APIPA address, assigned when a client cannot reach a DHCP server. A DHCP scope at 80% utilization still has 20% free addresses; therefore, the DHCP server is not out of IPs. The APIPA fallback indicates a lack of DHCP response, which is most likely due to a faulty or disconnected network cable preventing communication with the DHCP server.

Answer

The DNS server is not resolving domain names.

Answer

The DHCP server has run out of available IP addresses.

Answer

The subnet mask is incorrectly configured on the switch.

Question 4

A small office has a network with a router providing DHCP, an unmanaged switch, and several workstations. A user can access the internet but cannot print to a network printer that has a static IP address of 192.168.1.100. The user's workstation has an IP of 192.168.1.50. The printer is powered on and its network cable is connected to the switch. Which of the following should the technician do FIRST to troubleshoot the issue?

Accepted Answer

Check the printer's IP configuration by printing a network configuration page. Since the workstation can reach the internet, the switch and router are generally operational for that path. The printer is on the same subnet (192.168.1.100 vs .50), so routing between subnets is not the problem. However, the printer's actual IP configuration may be incorrect (e.g., wrong static IP, wrong subnet mask, or IP conflict). The first step is to verify the printer's network settings by printing a network configuration page; this provides direct information about its IP address and other parameters before assuming a hardware fault.

Answer

Replace the Ethernet cable connecting the printer to the switch

Answer

Restart the printer

Answer

Check the switch port status by looking at the LED indicators

Question 5

A network administrator sets up a new file server with a static IP address of 192.168.1.100. The server is connected to the company's main switch. For the first few hours, all clients can reach the server without issues. The next day, clients report they cannot connect to the server. The administrator finds that the server's IP address has been reassigned to a different device. The DHCP server is configured with a scope from 192.168.1.50 to 192.168.1.150. Which of the following is the BEST permanent solution to prevent this issue?

Accepted Answer

Change the server's static IP address to one outside the DHCP scope, such as 192.168.1.200. Moving the server's static IP to 192.168.1.200 places it outside the DHCP scope (192.168.1.50–150), eliminating the possibility of an IP address conflict with DHCP-assigned clients. This is a permanent solution that does not require changing the server's network configuration method or disabling DHCP for other devices. While an exclusion range (Option D) or DHCP reservation (Option A) can also prevent the conflict, a static IP outside the DHCP scope is generally preferred because it is simpler and does not depend on DHCP server configuration.

Answer

Configure a DHCP reservation for the server's MAC address and set the server to obtain an IP automatically

Answer

Disable the DHCP server entirely and configure all devices with static IPs

Answer

Leave the static IP at 192.168.1.100 and instruct the DHCP server to ignore that address

Question 6

A network technician is configuring a managed switch for a small office. The security policy requires that only specific authorized devices should be allowed to connect to the network via the switch ports. The technician wants the switch to automatically learn the MAC addresses of the first device that connects to each port and then lock that port to only that MAC address. Any other device connecting to the same port should be blocked. Which switch feature should be configured to accomplish this?

Accepted Answer

Port security with sticky MAC addresses.. Port security with sticky MAC addresses allows the switch to dynamically learn the MAC address of the first device connected to a port and then 'stick' that address to the port's configuration. Once learned, the switch will block any other MAC address from communicating on that port, enforcing the security policy that only the authorized device can connect.

Answer

802.1X authentication.

Answer

DHCP snooping.

Answer

VLAN hopping prevention.

Question 7

A user can access the internet and browse websites normally, but when they try to access a shared network drive by its hostname (\fileserver\share) the connection fails. Other users on the same network can access the drive using the hostname without issue. The technician can successfully ping the fileserver's IP address from the affected computer. Which of the following should the technician check NEXT?

Accepted Answer

The DNS server configuration on the computer. The user can browse the internet and ping the fileserver by IP, indicating basic IP connectivity and DNS resolution for external names are working. However, accessing the share by hostname fails while other users succeed, which isolates the issue to the local NetBIOS or LLMNR name resolution on the affected computer. Checking the DNS client configuration (including the primary DNS suffix and connection-specific suffixes) is the next logical step because the computer may not be appending the correct domain suffix to resolve the single-label hostname 'fileserver' to an IP address.

Answer

The firewall on the fileserver

Answer

The file and printer sharing service on the computer

Answer

The network cable connection

Question 8

A small office uses a router with DHCP service. One user reports that their computer can obtain an IP address in the 192.168.1.0/24 range, but cannot ping the default gateway (192.168.1.1). Other computers on the same network can ping the gateway and access the internet. The technician verifies the network cable shows link lights and the IP address is valid. Which of the following should the technician check NEXT?

Accepted Answer

B. The computer's subnet mask. The user's computer can obtain an IP address in the 192.168.1.0/24 range but cannot ping the default gateway, while other devices can. This indicates a host-specific layer-3 issue. A misconfigured subnet mask, such as 255.255.255.128 instead of 255.255.255.0, could cause the computer to compute a different network address and treat the gateway as on a remote network, thus failing to send ARP requests. The technician should verify the computer's subnet mask in its IP configuration.

Answer

A. The router's firewall settings

Answer

C. The router's DHCP pool size

Answer

D. The DNS server settings

Question 9

A small office uses a single router that provides DHCP services for the LAN. The router is connected to a switch, and all workstations are connected to the switch. Two workstations (Workstation A and Workstation B) are unable to obtain an IP address from DHCP. They both receive APIPA addresses. Other workstations on the same switch obtain IP addresses and can access the internet. The technician checks the router's DHCP server logs and sees that the pool is not exhausted. Which of the following is the MOST likely cause of the issue?

Accepted Answer

The switch ports used by the affected workstations are assigned to a different VLAN than the router. Workstations A and B are on switch ports configured for a different VLAN than the router. The DHCP Discover broadcasts from these workstations remain in their VLAN and never reach the router's DHCP server. As a result, they fail to obtain an IP address and use APIPA. Other workstations on the correct VLAN get DHCP and internet access. Since the DHCP pool is not exhausted, the issue is isolated to the affected ports, making a VLAN mismatch the most likely cause.

Answer

Port security on the switch is limiting the number of MAC addresses per port

Answer

The default gateway address is incorrect on the router

Answer

The DHCP relay agent on the switch is misconfigured

Question 10

A small office uses a single router that provides DHCP services for the LAN. The router is connected to a managed switch, and 20 workstations are connected to the switch. Two workstations (Workstation A and Workstation B) are unable to obtain an IP address from DHCP. They both receive APIPA addresses (169.254.x.x). Other workstations on the same switch obtain IP addresses and can access the internet. The technician checks the router's DHCP server logs and sees that the pool of available addresses is not exhausted. Which of the following is the MOST likely cause of the issue?

Accepted Answer

The switch ports for Workstation A and B are configured on a different VLAN that does not have DHCP access. If Workstation A and B are on a different VLAN that lacks a DHCP relay agent or a DHCP server configured for that VLAN, their DHCP discovery broadcasts will not reach the DHCP server. The router's DHCP logs show available addresses, ruling out exhaustion. Other workstations on the same physical switch obtain IPs because they are on a correctly configured VLAN. APIPA addresses are assigned when no DHCP response is received, which aligns with VLAN isolation blocking DHCP traffic.

Answer

The workstations have static IP addresses configured

Answer

The DHCP server is out of leases

Answer

The network cables for those workstations are faulty

Question 11

A technician is troubleshooting a user's computer that can successfully ping internal servers by IP address and hostname, but cannot access any external websites or services on the internet. The user can ping the default gateway (192.168.1.1). Other users on the same subnet have normal internet access. The technician has verified that the IP address, subnet mask, default gateway, and DNS server settings are correct on the user's computer. Which TWO of the following are the MOST likely causes of this issue? (Choose two.)

Accepted Answer

The computer has a static route configured with a low metric that bypasses the default gateway.. A static route with a low metric can override the default gateway for external traffic. If the computer has a manually configured route that points to a non-existent or unreachable next-hop for the 0.0.0.0/0 destination, all internet-bound packets will be sent there instead of the default gateway, breaking external access while internal pings (which match more specific routes) still work. Additionally, a manual proxy server configuration in the web browser can prevent access to external websites and services. If the proxy server is incorrect, unreachable, or no longer available, the browser will fail to connect to any external sites, while internal network communication (which does not rely on the proxy) continues to work. Since the user's IP configuration is correct and other users have internet, local misconfigurations like a bad static route or proxy setting are the most likely causes.

Answer

The DNS server is not resolving external domain names.

Answer

The default gateway is incorrect.

Question 12

A technician is installing a PoE security camera that is located 85 meters (279 feet) from the network switch. The switch does not support Power over Ethernet (PoE). The camera requires both data connectivity and power over the same Ethernet cable. Which of the following is the best solution?

Accepted Answer

Use a PoE injector at the switch location. A PoE injector at the switch location is the best solution because it adds power to the Ethernet cable without requiring a PoE switch. The camera is 85 meters away, which is within the 100-meter maximum for Ethernet (Cat 5e/6), so the existing cabling can carry both data and power when a PoE injector is used. This provides a cost-effective, single-cable solution for both connectivity and power.

Answer

Use a PoE power supply connected directly to the camera

Answer

Replace the existing cable with Cat 6a cabling

Answer

Use fiber optic cable with media converters at each end

Question 13

A technician is installing a new wireless router in a small office. The router is connected to a cable modem that has a solid online light. All wireless clients can connect to the router’s Wi-Fi network, but they cannot access the internet. Which of the following should the technician check NEXT?

Accepted Answer

Verify the router’s WAN port settings and ensure it is set to obtain an IP address automatically. The cable modem has a solid online light, indicating it is functioning correctly and has internet connectivity. Since wireless clients can connect to the router but cannot access the internet, the issue is likely that the router's WAN interface is not receiving a public IP address from the modem. The technician should verify the router's WAN port settings and ensure it is set to obtain an IP address automatically via DHCP, as cable modems typically assign IP addresses using DHCP. This is the most logical next step because the router must have a valid WAN IP to route traffic to the internet.

Answer

Replace the Ethernet cable between the router and modem

Answer

Disable the router’s DHCP server and assign static IPs to clients

Answer

Adjust the DNS server settings on the wireless clients

Question 14

A small business currently has a single router that provides internet access and DHCP services. The owner wants to add a second wireless router to extend Wi-Fi coverage to a far part of the building. The technician connects the WAN port of the new router to a LAN port on the existing router using a patch cable. Wireless clients can connect to the new router's SSID and obtain IP addresses, but they cannot access the internet or any resources on the main LAN. Which of the following is the most likely cause?

Accepted Answer

The existing router's DHCP pool is exhausted. The new router's WAN port connects to the existing LAN and expects to obtain an IP address via DHCP from the existing router. If the existing router's DHCP pool is exhausted, the new router's WAN port will not receive a valid IP configuration, leaving it without a gateway to the internet or the main LAN. Clients who connect to the new router's SSID get IP addresses from the new router's own DHCP server, but any traffic beyond the new router fails. Double NAT (A) would only occur if the WAN port had succeeded in getting an IP, and it would not by itself block all internet access.

Answer

The new router is performing NAT, causing double NAT

Answer

The new router's wireless security is set to WPA3

Answer

The patch cable is a crossover cable

Question 15

A small office uses a single DHCP server to assign IP addresses. Recently, several users have reported that their laptops cannot connect to the wired network. The technician runs ipconfig on one of the affected laptops and sees an IP address of 169.254.13.45 with a subnet mask of 255.255.0.0. The DHCP server shows that the scope has only 5 available addresses out of 100. Which of the following is the most likely cause of the problem?

Accepted Answer

The DHCP scope is exhausted due to the limited number of available addresses.. The IP address 169.254.13.45 with a subnet mask of 255.255.0.0 is an Automatic Private IP Addressing (APIPA) address, assigned by Windows when a DHCP server cannot be reached or does not have available addresses. Since the DHCP scope has only 5 available addresses out of 100, the scope is effectively exhausted, meaning new clients cannot obtain a lease and fall back to APIPA. This directly matches the symptom of multiple laptops failing to connect.

Answer

The DHCP server is overloaded and responding slowly.

Answer

The affected laptops have a static IP address configured.

Answer

The network switch is not forwarding DHCP broadcast requests.

Question 16

A small office network uses a router (192.168.1.1/24) and an unmanaged switch. A technician configures a server with a static IP address 192.168.1.100/24, gateway 192.168.1.1, and connects it to the switch. Workstations on the same subnet can ping the router (192.168.1.1) but cannot ping the server. The server can ping its own IP and the router. Which of the following is the MOST likely cause?

Accepted Answer

The server's firewall is blocking ICMP. The server can ping its own IP, indicating its IP stack is functioning. It can also ping the router, which confirms local network connectivity (the router is on the same subnet). Since workstations can reach the router but not the server, the issue is isolated to the server. The most likely cause is a host-level firewall blocking inbound ICMP echo requests, a common default on server operating systems.

Answer

The server has a duplicate IP address

Answer

The switch port is administratively disabled

Answer

The default gateway is incorrect

Question 17

A small office uses a single router with DHCP enabled (192.168.1.0/24). A technician configures a network printer with a static IP address of 192.168.1.150, subnet mask 255.255.255.0, default gateway 192.168.1.1, and DNS server 8.8.8.8. The printer is connected to the same switch as the workstations. Workstations can ping the router but cannot ping the printer. The printer can ping its own IP and the router. Which of the following is the MOST likely cause?

Accepted Answer

The printer's static IP address is within the DHCP scope.. The printer's static IP address 192.168.1.150 falls within the router's DHCP scope (typically 192.168.1.100–192.168.1.199 for a /24 network). When a DHCP server assigns an address to a workstation, it may hand out 192.168.1.150, creating an IP address conflict. This conflict causes intermittent or complete loss of connectivity to the printer because the router and switch see two devices claiming the same IP, and ARP tables become unstable. Workstations can ping the router because their own IPs are valid, but they cannot reach the printer due to the duplicate address.

Answer

The printer's firewall is blocking ICMP.

Answer

The printer's subnet mask is incorrect.

Answer

The printer's default gateway is incorrect.

Question 18

A technician is configuring a new VLAN for the accounting department on a managed switch. The switch is connected to a router-on-a-stick configuration for inter-VLAN routing. The technician creates VLAN 30 (Accounting) on the switch, assigns ports 6-10 to access mode in VLAN 30, and configures the switch's trunk port to the router to allow VLAN 30. The router's subinterface for VLAN 30 is configured with IP address 192.168.30.1/24. A workstation on port 6 (static IP 192.168.30.10/24) cannot communicate with a server on VLAN 20 (192.168.20.50/24) that it could reach previously when both were on the same VLAN. Other workstations in VLAN 30 can ping the router's subinterface (192.168.30.1). Which of the following is the MOST likely cause of the issue?

Accepted Answer

The workstation's default gateway is incorrect. The workstation can ping the router's subinterface (192.168.30.1) because both are on the same /24 subnet; this does not require a default gateway. To communicate with the server on VLAN 20 (192.168.20.50), the workstation must send traffic to its default gateway, which is the router. If the default gateway is not set to 192.168.30.1 or is misconfigured, the workstation will not be able to route off-subnet, even though it can still reach the router. The router has no ACL configured, and the symptoms are consistent with a default gateway issue.

Answer

The trunk port is not tagging VLAN 30 correctly

Answer

The server's IP address is on a different subnet than its VLAN

Answer

An ACL on the router is blocking traffic from VLAN 30 to VLAN 20

Question 19

A small office uses a DHCP server to assign IP configurations. A new laptop obtains an IP address of 192.168.1.50/24, default gateway 192.168.1.1, and DNS server 10.0.0.1. The laptop can ping the gateway and other local devices, but cannot resolve any domain names. Other devices on the network, which have the DNS server 192.168.1.10 configured, can access the internet without issues. Which of the following is the MOST likely cause?

Accepted Answer

The DNS server 10.0.0.1 is not reachable from this subnet. The laptop received a DNS server address of 10.0.0.1 via DHCP, which is on a different subnet (10.0.0.0/24) from the laptop's 192.168.1.0/24 network. Because the laptop has a default gateway of 192.168.1.1, it will forward traffic to 10.0.0.1 through that gateway. However, the gateway or routing infrastructure likely has no route to the 10.0.0.0/24 network, or the address 10.0.0.1 is not a functioning DNS server. Other devices on the same 192.168.1.0/24 subnet use the correct DNS server 192.168.1.10 and work fine, so the laptop's issue is specific to the DNS assignment from DHCP. The inability to resolve names while being able to ping local devices points directly to a DNS reachability or configuration problem.

Answer

The laptop's default gateway is incorrect

Answer

The laptop has a software firewall blocking DNS requests

Answer

The internet connection is down

Question 20

A small office network has two managed switches, Switch A and Switch B, connected via a trunk link. Switch A has VLAN 10 (192.168.10.0/24) and VLAN 20 (192.168.20.0/24) configured. Switch B has only VLAN 10 configured. A router-on-a-stick is connected to Switch A and performs inter-VLAN routing. A workstation connected to an access port on Switch B in VLAN 10 can ping other devices in VLAN 10 on both switches, but it cannot ping a server in VLAN 20 that is connected to Switch A. The trunk port on Switch B is configured to allow all VLANs. Which of the following is the MOST likely cause of this issue?

Accepted Answer

The router's subinterface for VLAN 20 has an incorrect IP address or subnet mask.. The workstation in VLAN 10 can communicate across the trunk to Switch A, confirming that the trunk carries VLAN 10 successfully. Inter-VLAN routing requires the workstation to send traffic to its default gateway (the router). The router then routes to VLAN 20 and delivers the traffic to the server, which is directly attached to Switch A. VLAN 20 frames never need to cross the trunk between Switch A and Switch B, because no VLAN 20 devices exist on Switch B. Therefore, the most likely cause of the failure is an incorrect IP address or subnet mask on the router's VLAN 20 subinterface, which prevents proper routing to the server's network.

Answer

The trunk port on Switch A is not configured to allow VLAN 20 traffic.

Answer

The workstation's default gateway is set incorrectly.

Answer

The switchport mode on Switch B's trunk port is set to access mode.