220-1101 Networking — 50 Questions

Question 1

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?

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

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 2

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 3

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 4

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 5

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 6

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 7

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 8

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 9

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 10

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 11

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 12

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 13

A small office network uses a 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. Workstations on the same subnet can ping the router (192.168.1.1) and other workstations, 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 and conflicts with a lease assigned to another device.. The printer's static IP address 192.168.1.150 falls within the DHCP scope (192.168.1.0/24). If the DHCP server has already leased that address to another device, a conflict occurs. The printer can ping its own IP and the router because its local stack and gateway are configured correctly, but workstations cannot reach it because the router's ARP table or the switch may map the IP to the wrong MAC address, or the conflicting device actively responds to ARP requests, causing communication failures.

Answer

The printer's default gateway is set incorrectly.

Answer

The printer's subnet mask is incorrect.

Answer

The switch port the printer is connected to is malfunctioning.

Question 14

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 15

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 16

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.

Question 17

A small office network uses a single managed switch connected to a router. A workstation is configured with a static IP address of 10.0.0.50/24, default gateway 10.0.0.1, and DNS server 10.0.0.10. The workstation can successfully ping other workstations on the same local subnet, but it cannot ping the default gateway (10.0.0.1) or access the internet. The technician checks the router and finds that the router's interface connected to the switch has IP address 10.0.0.1/24. The switch port connecting the router is configured as an access port on VLAN 1. The workstation's switch port is configured as an access port on VLAN 10. Other workstations on VLAN 10 have the same issue. Which of the following is the MOST likely cause?

Accepted Answer

The switch is not trunking to the router. The workstation is on VLAN 10, but the switch port connected to the router is configured as an access port on VLAN 1. This places the router's interface in VLAN 1 and prevents it from receiving any VLAN 10 traffic. The workstation's ARP requests for the default gateway (10.0.0.1) remain isolated to VLAN 10, so the router never responds. The router must have Layer 2 access to VLAN 10, either by changing the switch port to an access port on VLAN 10 or by configuring the link as a trunk with a subinterface for VLAN 10. Since the switch port is not a trunk, the lack of a subinterface is not the root cause; the absence of trunking (or proper VLAN assignment) is the issue.

Answer

The router's interface does not have a subinterface configured for VLAN 10

Answer

The default gateway IP address is incorrect

Answer

The DNS server is unreachable

Question 18

A small office network consists of a router (192.168.1.1/24) connected to a managed switch. The switch has all ports configured as access ports on VLAN 1. A workstation obtains an IP address of 192.168.1.50/24 from the DHCP server running on the router. The workstation can successfully ping other workstations in the same subnet but cannot ping the default gateway (192.168.1.1). The router's LAN interface is configured with IP address 10.0.0.1/24. Which of the following is the MOST likely cause?

Accepted Answer

The router's LAN interface is on a different subnet than the workstations.. The router's LAN interface is configured with IP address 10.0.0.1/24, while the workstation has an IP address of 192.168.1.50/24. Since these are on different subnets, the workstation cannot reach the default gateway (192.168.1.1) because that address does not exist on the router's LAN interface. The router will not respond to ARP requests for 192.168.1.1, and the workstation cannot send traffic outside its own subnet without a valid gateway on the same subnet.

Answer

The workstation's default gateway is set incorrectly due to a DHCP scope misconfiguration.

Answer

The switch port the workstation is connected to is in the wrong VLAN.

Answer

The Ethernet cable is faulty.

Question 19

A user configures a workstation with a static IP address of 192.168.1.50, subnet mask 255.0.0.0, default gateway 192.168.1.1, and DNS server 8.8.8.8. The workstation can ping other computers on the local network (e.g., 192.168.1.100) but cannot ping the default gateway (192.168.1.1) or access the internet. Other workstations using DHCP on the same network have no issues. Which of the following is the MOST likely cause?

Accepted Answer

The default gateway IP address is incorrect; it should be 192.168.0.1.. With subnet mask 255.0.0.0, the workstation is in the 192.0.0.0/8 network. Both its own IP (192.168.1.50) and the default gateway (192.168.1.1) have the same first octet, so the gateway is considered to be on the same local subnet. Therefore, the workstation will send ARP requests directly to the gateway. If the gateway IP is not actually present on the network (e.g., the correct gateway is 192.168.0.1), the ping fails. DNS is irrelevant to IP ping, and an IP conflict would typically cause intermittent issues, not a consistent inability to ping the gateway. The most likely cause is an incorrect default gateway address.

Answer

The subnet mask is incorrectly set to 255.0.0.0, causing the gateway to be considered a remote host.

Answer

The DNS server address is incorrect; the workstation should use a local DNS server.

Answer

The static IP address conflicts with another device on the network.

Question 20

A technician replaced an unmanaged network switch with a new managed switch in a small office. After reconnecting all devices, some workstations can access the internet, but others cannot. The workstations that cannot access the internet are physically connected to the switch and their link lights are on. The technician checks the switch configuration and finds that all ports are set to 'trunk' mode by default. The router is connected to port 1, which is also set to trunk mode. Which of the following is the MOST likely cause?

Accepted Answer

The switch ports that are connected to workstations need to be configured as access ports instead of trunk ports. Managed switch trunk ports are designed to carry multiple VLANs between switches/routers and tag frames with 802.1Q, except on the native VLAN. Workstations send untagged frames and expect an access port assigned to one VLAN. Connecting workstations to trunk ports is a misconfiguration: their untagged frames will be placed into the trunk's native VLAN, which may work only if that native VLAN aligns with the router's configuration, but it is not the correct design and can cause the partial connectivity described. The workstation ports should be changed to access ports.

Answer

The router does not support trunking

Answer

The Ethernet cables are faulty

Answer

The workstations have incorrect IP settings