220-1101 IP Addressing — 20 Questions

Question 1

A technician is troubleshooting a network where two computers cannot communicate. Computer A has an IP of 192.168.1.10 with subnet mask 255.255.255.0. Computer B has an IP of 192.168.2.20 with subnet mask 255.255.255.0. Both are connected to the same switch. The switch is not configured with VLANs. Why can't the computers communicate?

Accepted Answer

The computers are on different subnets and need a router to communicate.. Even though both computers are on the same physical switch, they are on different logical subnets (192.168.1.0/24 and 192.168.2.0/24). Without a router to forward traffic between subnets, they cannot communicate directly.

Answer

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

Answer

The subnet mask on Computer B is incorrect.

Answer

The default gateway on both computers is not set.

Question 2

A user complains that they cannot access a website by its domain name, but they can access it by typing the IP address directly. The user's computer is configured to obtain DNS automatically. What is the most likely issue?

Accepted Answer

The DNS server is not responding or is misconfigured.. When a user can access a site by IP but not by domain name, it indicates a DNS resolution problem. The DNS server may be unreachable or not configured correctly.

Answer

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

Answer

The user's browser cache is corrupted.

Answer

The website's IP address has changed.

Question 3

A user reports that they can only access the internet intermittently. The technician runs ipconfig and sees an IPv4 address of 192.168.1.105 with a subnet mask of 255.255.255.0 and a default gateway of 192.168.1.1. The technician pings the gateway successfully, but pings to 8.8.8.8 fail. What is the most likely issue?

Accepted Answer

The router's WAN connection is down or misconfigured.. Successful ping to the gateway indicates local network connectivity is fine. Failure to ping an external IP like 8.8.8.8 suggests the router is not forwarding traffic to the internet, possibly due to a WAN configuration issue or ISP problem.

Answer

The user's computer has a duplicate IP address.

Answer

The DNS server is not resolving addresses.

Answer

The user's firewall is blocking ICMP traffic.

Question 4

A company has a network with the IP range 172.16.0.0/16. They need to create 8 separate subnets for different departments, each with at least 1000 usable hosts. What subnet mask should be used?

Accepted Answer

255.255.224.0. To create 8 subnets from a /16 network, you need to borrow 3 bits (2^3=8 subnets). This gives a /19 subnet mask (255.255.224.0), which provides 8190 usable hosts per subnet (2^13-2), meeting the requirement of at least 1000 hosts.

Answer

255.255.240.0

Answer

255.255.248.0

Answer

255.255.192.0

Question 5

A user reports that their laptop can connect to the internet when using a wired connection at home, but cannot connect to any network resources when using Wi-Fi at the office. The office uses DHCP with a scope of 192.168.10.0/24. The laptop's IP configuration shows an address of 169.254.15.22. What is the most likely cause of this issue?

Accepted Answer

The laptop cannot reach the DHCP server on the office network.. The address 169.254.x.x is an Automatic Private IP Addressing (APIPA) address, assigned when a DHCP server is unreachable. This indicates the laptop failed to obtain a valid IP from the office DHCP server, likely due to a connectivity or server issue.

Answer

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

Answer

The office DHCP server is out of available IP addresses.

Answer

The laptop's DNS settings are misconfigured.

Question 6

A network administrator is designing a new subnet scheme for a company with 4 departments: Sales (50 devices), HR (25 devices), IT (10 devices), and Management (5 devices). The company uses the 10.0.0.0/8 network. To minimize wasted IP addresses, which subnet mask should be used for the Sales department?

Accepted Answer

255.255.255.192. To accommodate 50 devices, you need at least 52 usable addresses (50 + 2 for network and broadcast). A /26 subnet mask (255.255.255.192) provides 62 usable hosts, which is the smallest subnet that can support 50 devices without wasting many addresses.

Answer

255.255.255.0

Answer

255.255.255.224

Answer

255.255.255.240

Question 7

A technician is troubleshooting a network where several users cannot access the internet, but they can communicate with each other. The network uses a router with IP 10.0.0.1 and a subnet mask of 255.255.255.0. All computers have IPs in the 10.0.0.0/24 range. What is the most likely cause?

Accepted Answer

The default gateway on the computers is not set to 10.0.0.1.. If users can communicate locally but not access the internet, the issue is likely with the default gateway. The gateway must be correctly configured on each device and the router must have a route to the internet.

Answer

The DNS server address is set to 10.0.0.1.

Answer

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

Answer

The router's DHCP server is disabled.

Question 8

A technician is configuring a small office network with 15 computers and a single router. The router's WAN port is connected to a cable modem, and the LAN port is connected to a switch. All computers are connected to the switch. The technician assigns the router's LAN interface the IP 192.168.0.1/24. What should be the default gateway setting on each computer?

Accepted Answer

192.168.0.1. The default gateway is the IP address of the router's LAN interface, which is 192.168.0.1. This allows computers to send traffic outside their local subnet, such as to the internet.

Answer

The IP address of the cable modem.

Answer

The IP address of the switch.

Answer

192.168.0.255

Question 9

A technician is setting up a new server that must always have the same IP address on a network using DHCP. The network administrator wants to avoid manually configuring the server's IP to prevent misconfiguration. Which method should be used to ensure the server receives the same IP from the DHCP server?

Accepted Answer

Configure a DHCP reservation on the router for the server's MAC address.. A DHCP reservation ties a specific MAC address to a specific IP address in the DHCP server's configuration. This ensures the server always gets the same IP without manual static configuration.

Answer

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

Answer

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

Answer

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

Question 10

A small business uses a router with a default IP of 192.168.1.1. The owner wants to set up a new printer with a static IP of 192.168.1.50. After configuring the printer, it cannot be accessed from any computer on the network. All computers are set to obtain IP addresses automatically. What is the most likely problem?

Accepted Answer

The printer's IP address conflicts with an address already assigned by DHCP.. The printer's static IP falls within the router's DHCP scope, which typically includes 192.168.1.2 to 192.168.1.254 unless modified. This can cause an IP conflict if the router assigns that address to another device.

Answer

The printer's subnet mask is set to 255.0.0.0.

Answer

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

Answer

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

Question 11

A technician is troubleshooting a user's computer that cannot access a web server at 10.10.10.50. The user's IP is 10.10.20.15 with subnet mask 255.255.0.0. The technician can ping 10.10.10.50 from the user's computer. What should the technician check next?

Accepted Answer

The web server's firewall settings.. Since the user can ping the web server, network connectivity and IP addressing are correct. The issue is likely at the application layer, such as a firewall blocking HTTP/HTTPS or a misconfigured web server. This tests the OSI model and troubleshooting methodology.

Answer

The default gateway setting on the user's computer.

Answer

The user's IP address for a conflict.

Answer

The subnet mask on the user's computer.

Question 12

A user reports that they cannot access the internet, but they can ping other devices on the local network. The technician checks the IP configuration and sees: IP: 192.168.1.25, Subnet Mask: 255.255.255.0, Default Gateway: 192.168.2.1. What is the issue?

Accepted Answer

The default gateway is on a different subnet.. The default gateway must be on the same subnet as the device's IP. Here, the IP is on 192.168.1.0/24, but the gateway is on 192.168.2.0/24, so traffic cannot be routed out. This tests the concept that the gateway must be reachable locally.

Answer

The subnet mask is incorrect.

Answer

The IP address is a broadcast address.

Answer

The DNS server is misconfigured.

Question 13

A technician is troubleshooting a user's inability to reach a server at 172.16.50.100. The user's IP is 172.16.50.50 with subnet mask 255.255.255.0. The technician runs a traceroute and sees the first hop is the gateway (172.16.50.1), but the second hop times out. What does this indicate?

Accepted Answer

There is a routing problem between the gateway and the server.. The user can reach the local gateway, but the next hop (likely a router) is not responding. This suggests a routing issue beyond the local network, such as a misconfigured router or firewall blocking ICMP. This tests understanding of traceroute and routing path analysis.

Answer

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

Answer

The server is powered off.

Answer

The user's default gateway is incorrect.

Question 14

A customer reports that their laptop can connect to the internet at home but not at a coffee shop. The coffee shop uses a /24 subnet with a gateway of 192.168.1.1. The laptop's IP is 192.168.2.10. What is the most likely cause?

Accepted Answer

The laptop's IP address is on a different subnet than the coffee shop's network.. The laptop's IP address is on a different subnet (192.168.2.0/24) than the coffee shop's network (192.168.1.0/24), so it cannot communicate with the gateway. This tests understanding of subnetting and how devices must be on the same subnet to reach the default gateway.

Answer

The DNS server address is incorrect.

Answer

The wireless card is faulty.

Answer

The subnet mask is set to 255.0.0.0.

Question 15

A technician is setting up a small office with 15 devices and needs to assign private IP addresses. The router's LAN interface is 10.0.0.1/24. Which of the following is a valid IP address for a workstation on this network?

Accepted Answer

10.0.0.50. The /24 subnet means the network is 10.0.0.0 with a range of 10.0.0.1 to 10.0.0.254. 10.0.0.50 falls within this range and is not reserved. This tests understanding of private IP ranges and subnet boundaries.

Answer

10.0.1.50

Answer

10.0.0.0

Answer

10.0.0.255

Question 16

A small business uses a router with DHCP enabled, issuing addresses in the 192.168.1.0/24 range. A technician installs a new server with a static IP of 192.168.1.50, but users cannot connect to it. The technician pings 192.168.1.50 from the server itself successfully. What is the most likely cause?

Accepted Answer

Another device on the network has the same IP address.. If the DHCP server assigned 192.168.1.50 to another device, there is an IP address conflict. The server can ping itself because it uses its own IP, but other devices may have the same IP or the server's address is already in use. This tests understanding of IP conflicts and static vs. DHCP assignments.

Answer

The server's subnet mask is set to 255.255.255.0.

Answer

The server's default gateway is missing.

Answer

The server's network cable is faulty.

Question 17

A technician is configuring a new printer on a network with the IP 172.16.0.50 and subnet mask 255.255.0.0. The router's LAN IP is 172.16.0.1. A workstation with IP 172.16.1.10 can ping the printer, but a workstation with IP 172.17.0.10 cannot. What is the most likely reason?

Accepted Answer

The workstation with IP 172.17.0.10 is on a different network and needs a router to reach the printer.. The subnet mask 255.255.0.0 means the network is 172.16.0.0/16, so 172.16.1.10 is on the same network, but 172.17.0.10 is on a different network (172.17.0.0/16). Without a router between them, they cannot communicate. This tests understanding of subnetting and how the subnet mask defines the network boundary.

Answer

The printer's subnet mask is wrong.

Answer

The printer has a duplicate IP address.

Answer

The default gateway on the printer is missing.

Question 18

A network administrator is troubleshooting a connectivity issue between two servers. Server A has IP 192.168.10.25/25, and Server B has IP 192.168.10.200/25. Server A can ping its default gateway (192.168.10.1) but cannot ping Server B. What is the most likely cause?

Accepted Answer

The servers are on different subnets and require a router to communicate.. A /25 subnet mask (255.255.255.128) divides the 192.168.10.0/24 network into two subnets: 192.168.10.0/25 (hosts 1-126) and 192.168.10.128/25 (hosts 129-254). Server A (25) is on the first subnet, Server B (200) on the second. They need a router to communicate. This tests advanced subnetting.

Answer

Server A has a duplicate IP address.

Answer

The subnet mask is incorrect on one of the servers.

Answer

The default gateway is misconfigured.

Question 19

A technician is setting up a new branch office and needs to assign IPs to 30 devices. The ISP provided a public IP block of 203.0.113.0/28. The technician decides to use private IPs internally and NAT. Which of the following is the most appropriate private IP range for this network?

Accepted Answer

192.168.1.0/24. For a small network with 30 devices, a /24 subnet (e.g., 192.168.1.0/24) provides 254 usable addresses, which is sufficient. The /28 public block is for the WAN interface. This tests knowledge of private IP ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) and subnet sizing.

Answer

203.0.113.1 to 203.0.113.14

Answer

10.0.0.0/8

Answer

172.16.0.0/12

Question 20

A technician is configuring a router with two interfaces: WAN (DHCP from ISP) and LAN (static IP 10.0.0.1/24). The technician sets the LAN subnet mask to 255.255.255.0. A workstation is assigned IP 10.0.0.100/24 and can ping the router, but cannot access the internet. The router's WAN interface has IP 203.0.113.5/30. What is the most likely missing configuration?

Accepted Answer

The router lacks a default route pointing to the ISP's gateway.. The workstation can reach the router, so the LAN is fine. The router has a WAN IP, but without a default route (or NAT), traffic from the LAN cannot be forwarded to the internet. The /30 WAN subnet only has two usable IPs, so the router needs a route to the ISP's next hop. This tests routing and NAT concepts.

Answer

The workstation's default gateway is set to 10.0.0.1.

Answer

The WAN subnet mask should be 255.255.255.0.

Answer

The LAN subnet mask should be 255.255.0.0.