IP Addressing practice questions

The switch is blocking the traffic due to MAC address filtering.

Why wrong: MAC filtering would block specific devices, but it would not explain why two devices on different subnets cannot communicate.

The subnet mask on Computer B is incorrect.

Why wrong: The subnet mask is correct for its own subnet (255.255.255.0), but the problem is that they are on different subnets.

The default gateway on both computers is not set.

Why wrong: A default gateway is needed to reach other subnets, but even if set, it would not enable direct communication without a router.

The user's computer has a static IP address that conflicts with another device.

Why wrong: An IP conflict would cause connectivity issues overall, not just with DNS resolution.

The user's browser cache is corrupted.

Why wrong: A corrupted browser cache might cause issues loading a page, but it would not prevent DNS resolution entirely.

The website's IP address has changed.

Why wrong: If the IP address changed, the user would not be able to access it by the old IP either.

The user's computer has a duplicate IP address.

Why wrong: A duplicate IP would cause intermittent connectivity, but pinging the gateway would likely fail or be inconsistent.

The DNS server is not resolving addresses.

Why wrong: DNS issues would affect name resolution, but pinging 8.8.8.8 uses an IP address, not a domain name, so DNS is not involved.

The user's firewall is blocking ICMP traffic.

Why wrong: A local firewall could block ping, but it would not explain why internet access is intermittent for other applications.

255.255.240.0

Why wrong: This is a /20 subnet mask, which would provide 16 subnets (2^4) but only 4094 usable hosts per subnet, which is sufficient but not the most efficient for exactly 8 subnets.

255.255.248.0

Why wrong: This is a /21 subnet mask, which would provide 32 subnets (2^5) but only 2046 usable hosts per subnet, which is enough but not the best fit for exactly 8 subnets.

255.255.192.0

Why wrong: This is a /18 subnet mask, which would provide 4 subnets (2^2), not enough to create 8 separate subnets.

The laptop's Wi-Fi adapter is disabled in Device Manager.

Why wrong: If the adapter were disabled, the laptop would not have any IP address assigned, not an APIPA address.

The office DHCP server is out of available IP addresses.

Why wrong: An exhausted DHCP scope would cause the server to not respond, but the client would still attempt DHCP and eventually fall back to APIPA. However, the most common cause is the DHCP server being unreachable, not necessarily exhausted.

The laptop's DNS settings are misconfigured.

Why wrong: DNS misconfiguration would not cause an APIPA address; it would affect name resolution after a valid IP is obtained.

255.255.255.0

Why wrong: A /24 subnet provides 254 usable hosts, which is far more than needed for 50 devices and would waste IP addresses.

255.255.255.224

Why wrong: A /27 subnet provides 30 usable hosts, which is not enough for 50 devices.

255.255.255.240

Why wrong: A /28 subnet provides 14 usable hosts, which is far too few for 50 devices.

The DNS server address is set to 10.0.0.1.

Why wrong: While DNS could be an issue, the ability to communicate locally suggests the network is working. The lack of internet access points to a default gateway problem.

The subnet mask is incorrectly set to 255.255.0.0 on some computers.

Why wrong: An incorrect subnet mask could cause communication issues, but if they can communicate with each other, the subnet mask is likely correct.

The router's DHCP server is disabled.

Why wrong: If DHCP were disabled, computers might not have IP addresses at all, but they are communicating locally, so they have valid IPs.

The IP address of the cable modem.

Why wrong: The cable modem is on the WAN side and is not reachable from the LAN without going through the router.

The IP address of the switch.

Why wrong: A switch typically does not have an IP address that functions as a gateway; it is a Layer 2 device.

192.168.0.255

Why wrong: This is the broadcast address for the 192.168.0.0/24 network and cannot be assigned to a device.

Set the server to use a static IP address outside the DHCP scope.

Why wrong: This would work but violates the requirement to avoid manual configuration.

Set the server's IP address to 169.254.x.x.

Why wrong: APIPA addresses are self-assigned and not routable, so the server would not be reachable on the network.

Disable the server's network adapter and re-enable it.

Why wrong: This would only renew the IP lease, but the server could still receive a different IP from DHCP.

The printer's subnet mask is set to 255.0.0.0.

Why wrong: While an incorrect subnet mask can cause issues, the default subnet mask for a 192.168.x.x network is 255.255.255.0, and a mismatch would still not explain the lack of access if the IP was valid.

The printer's IP address is outside the router's DHCP range.

Why wrong: 192.168.1.50 is inside the typical DHCP range, so this would not cause a conflict.

The printer is not connected to the network via an Ethernet cable.

Why wrong: While a physical connection issue could cause problems, the scenario implies the printer is configured but unreachable, and the most common cause is an IP conflict.

The default gateway setting on the user's computer.

Why wrong: Pinging the server successfully shows that routing is working, so the gateway is likely correct.

The user's IP address for a conflict.

Why wrong: An IP conflict would cause intermittent connectivity, but the successful ping indicates no conflict.

The subnet mask on the user's computer.

Why wrong: The subnet mask 255.255.0.0 allows communication between 10.10.20.15 and 10.10.10.50, as they are on the same /16 network.

The subnet mask is incorrect.

Why wrong: The subnet mask 255.255.255.0 is correct for a /24 network and matches the IP.

The IP address is a broadcast address.

Why wrong: 192.168.1.25 is a valid host address, not the broadcast address (which would be 192.168.1.255).

The DNS server is misconfigured.

Why wrong: DNS issues would affect name resolution, but the inability to ping the gateway indicates a routing problem, not DNS.

The user's IP address is in the wrong subnet.

Why wrong: The user's IP 172.16.50.50 with mask 255.255.255.0 is on the same subnet as the gateway, so that is correct.

The server is powered off.

Why wrong: If the server were off, the traceroute would likely fail at the first hop or show no response, but here the first hop succeeds.

The user's default gateway is incorrect.

Why wrong: The user's default gateway is 172.16.50.1, and the traceroute shows it as the first hop, so it is correct.

The DNS server address is incorrect.

Why wrong: DNS issues would affect name resolution, but the laptop cannot even reach the gateway, so this is not the primary cause.

The wireless card is faulty.

Why wrong: The laptop works at home, so the wireless card is functional; the issue is network configuration.

The subnet mask is set to 255.0.0.0.

Why wrong: A /24 subnet mask is 255.255.255.0; using 255.0.0.0 would make the laptop think it's on a larger network, but the specific mismatch here is the IP range.

10.0.1.50

Why wrong: 10.0.1.50 is on the 10.0.1.0/24 subnet, not the 10.0.0.0/24 subnet of the router.

10.0.0.0

Why wrong: 10.0.0.0 is the network address and is reserved; it cannot be assigned to a host.

10.0.0.255

Why wrong: 10.0.0.255 is the broadcast address for the /24 subnet and cannot be assigned to a host.

The server's subnet mask is set to 255.255.255.0.

Why wrong: A subnet mask of 255.255.255.0 is correct for a /24 network and would not cause connectivity issues.

The server's default gateway is missing.

Why wrong: A missing gateway would prevent internet access but not local connectivity; users on the same subnet should still be able to reach the server.

The server's network cable is faulty.

Why wrong: If the cable were faulty, the server would not be able to ping itself or respond to pings; the server can ping itself, indicating the network stack is working.

The printer's subnet mask is wrong.

Why wrong: The printer's subnet mask 255.255.0.0 is correct for the 172.16.0.0 network; the issue is with the other workstation's network.

The printer has a duplicate IP address.

Why wrong: There is no indication of a duplicate IP; the printer is reachable from one workstation.

The default gateway on the printer is missing.

Why wrong: A default gateway is only needed to reach other networks, but the printer can be reached from within its own network; the issue is the other workstation's location.

Server A has a duplicate IP address.

Why wrong: A duplicate IP would cause intermittent issues, but Server A can ping the gateway, indicating no conflict on its subnet.

The subnet mask is incorrect on one of the servers.

Why wrong: Both servers use /25, which is consistent; the issue is that they are on different subnets within the same /24 block.

The default gateway is misconfigured.

Why wrong: Server A can ping the gateway, so the gateway is reachable; the issue is between the servers, not the gateway.

203.0.113.1 to 203.0.113.14

Why wrong: These are public IPs from the ISP's block, not private IPs; they should be used for the router's WAN interface, not internal devices.

10.0.0.0/8

Why wrong: 10.0.0.0/8 is a private range but is far too large for 30 devices; it would work but is not the most appropriate choice for a small office.

172.16.0.0/12

Why wrong: 172.16.0.0/12 is a private range but is typically used for larger networks; it is less common for small offices and is not the most appropriate.

The workstation's default gateway is set to 10.0.0.1.

Why wrong: The workstation can ping the router, so the gateway is correctly set to 10.0.0.1.

The WAN subnet mask should be 255.255.255.0.

Why wrong: The ISP provided a /30 subnet, which is correct for a point-to-point link; changing it would break connectivity.

The LAN subnet mask should be 255.255.0.0.

Why wrong: The /24 mask is appropriate for the LAN and allows communication; changing it would not fix the internet issue.