Question 129 of 1,819
Network Infrastructure and ConnectivitymediumMultiple ChoiceObjective-mapped

Quick Answer

The correct answer is to set the subnet mask to 255.255.255.0 and the default gateway to 192.168.1.1. This works because a /24 subnet mask (255.255.255.0) precisely matches the network prefix of the default gateway, ensuring the workstation correctly identifies its local subnet and can route traffic beyond it to the internet. On the CCNA 200-301 v2 exam, this tests your understanding of how a host uses its subnet mask to determine whether a destination is local or remote—a fundamental routing concept. A common trap is choosing a /16 mask, which would make the host think the gateway is on the same subnet when it isn’t, or leaving the gateway blank, which kills all off-subnet communication. For a quick memory tip, remember that the subnet mask and default gateway must share the same network portion: if the gateway is 192.168.1.1 and the IP is 192.168.1.50, the mask must be 255.255.255.0 to keep them in the same /24 network.

CCNA Network Infrastructure and Connectivity Practice Question

This 200-301 practice question tests your understanding of network infrastructure and connectivity. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

A junior network engineer is configuring a new Windows 10 workstation to connect to the corporate network. The network uses a /24 subnet mask and has a default gateway of 192.168.1.1. The workstation obtains its IP address automatically from a DHCP server, but the engineer needs to manually set a static IPv4 address of 192.168.1.50 and ensure the workstation can reach the internet. Which configuration step must the engineer take to satisfy these requirements?

Question 1mediummultiple choice
Read the full DHCP explanation →

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

Set the subnet mask to 255.255.255.0 and the default gateway to 192.168.1.1

Option B is correct because a /24 subnet mask (255.255.255.0) matches the network prefix of the default gateway 192.168.1.1, ensuring the workstation can route traffic to the internet via that gateway. Option A fails because a /16 mask (255.255.0.0) does not match the corporate /24 network, causing incorrect network identification and potential routing issues. Option C fails because leaving the default gateway blank means the host cannot reach any network beyond its local subnet, so internet access is impossible. Option D fails because using the host's own IP (192.168.1.50) as the default gateway would cause the host to attempt to route traffic to itself, never reaching the actual gateway.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • Set the subnet mask to 255.255.0.0 and the default gateway to 192.168.1.1

    Why it's wrong here

    Using a /16 subnet mask (255.255.0.0) is incorrect for a /24 network. This would cause the workstation to consider a much larger range of addresses as local, leading to incorrect routing decisions and potential connectivity problems.

  • Set the subnet mask to 255.255.255.0 and the default gateway to 192.168.1.1

    Why this is correct

    This is the correct configuration. The subnet mask 255.255.255.0 corresponds to a /24 prefix, which matches the network. The default gateway 192.168.1.1 is the router's IP on the same subnet, allowing the workstation to reach the internet.

    Related concept

    Read the scenario before looking for a memorised answer.

  • Set the subnet mask to 255.255.255.0 and leave the default gateway blank

    Why it's wrong here

    Leaving the default gateway blank means the workstation will not know how to reach destinations outside its own subnet, so it cannot access the internet or any other network beyond the local segment.

  • Set the subnet mask to 255.255.255.0 and the default gateway to 192.168.1.50

    Why it's wrong here

    Setting the default gateway to 192.168.1.50 (the workstation's own IP) is invalid. The gateway must be a different device (typically a router) on the same subnet; otherwise, the workstation would try to route traffic to itself, which fails.

Option-by-option analysis

Why each answer is right or wrong

Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.

Set the subnet mask to 255.255.255.0 and the default gateway to 192.168.1.1Correct answer

Why this is correct

This is the correct configuration. The subnet mask 255.255.255.0 corresponds to a /24 prefix, which matches the network. The default gateway 192.168.1.1 is the router's IP on the same subnet, allowing the workstation to reach the internet.

Set the subnet mask to 255.255.0.0 and the default gateway to 192.168.1.1Wrong answer — click to see why

Why this is wrong here

Setting the subnet mask to 255.255.0.0 (/16) on a /24 network causes the workstation to consider IP addresses outside the local /24 subnet as local, leading to incorrect routing decisions. The workstation will not send traffic to the default gateway for destinations that are actually remote, resulting in connectivity failures.

Why candidates choose this

A student might confuse subnet masks and think that a larger subnet mask (like /16) is more permissive or 'better' for connectivity, not realizing that it actually disrupts proper routing by misidentifying which addresses are local.

Set the subnet mask to 255.255.255.0 and leave the default gateway blankWrong answer — click to see why

Why this is wrong here

Leaving the default gateway blank means the workstation has no route to destinations outside its own subnet. Without a default gateway, the workstation cannot send traffic to the internet or any other network beyond the local segment, even though it can communicate with devices on the same subnet.

Why candidates choose this

A student might think that a default gateway is optional or only needed for certain types of traffic, not realizing that it is essential for reaching any off-subnet destination, including internet access.

Set the subnet mask to 255.255.255.0 and the default gateway to 192.168.1.50Wrong answer — click to see why

Why this is wrong here

Setting the default gateway to the workstation's own IP address (192.168.1.50) is invalid because the gateway must be a different device, typically a router. The workstation would attempt to route traffic to itself, which fails, as no device can forward packets to itself as a gateway.

Why candidates choose this

A student might mistakenly think that the default gateway should be the same as the workstation's IP address, confusing it with the concept of a loopback address or simply not understanding that the gateway must be a separate device on the same subnet.

Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”

Common exam traps

Common exam trap: answer the scenario, not the keyword

Cisco often tests the requirement that the default gateway must be on the same subnet as the host's IP address, and a common trap is to confuse the gateway address with the host's own IP or to use an incorrect subnet mask that still allows local communication but breaks routing.

Detailed technical explanation

How to think about this question

When manually configuring a static IPv4 address, the subnet mask defines the network portion of the address; a mismatch between the host's subnet mask and the gateway's subnet mask can cause the host to incorrectly determine whether a destination is local or remote. In Windows, the default gateway must be on the same subnet as the host's IP address; otherwise, the route is ignored. This is enforced by the TCP/IP stack, which uses the subnet mask to compute the network ID and validates that the gateway falls within that network.

KKey Concepts to Remember

  • Read the scenario before looking for a memorised answer.
  • Find the constraint that changes the correct option.
  • Eliminate answers that are true in general but not in this case.

TExam Day Tips

  • Watch for words such as best, first, most likely and least administrative effort.
  • Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Real-world example

How this comes up in practice

A network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.

What to study next

Got this wrong? Here's your next step.

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

Related practice questions

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FAQ

Questions learners often ask

What does this 200-301 question test?

Network Infrastructure and Connectivity — This question tests Network Infrastructure and Connectivity — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: Set the subnet mask to 255.255.255.0 and the default gateway to 192.168.1.1 — Option B is correct because a /24 subnet mask (255.255.255.0) matches the network prefix of the default gateway 192.168.1.1, ensuring the workstation can route traffic to the internet via that gateway. Option A fails because a /16 mask (255.255.0.0) does not match the corporate /24 network, causing incorrect network identification and potential routing issues. Option C fails because leaving the default gateway blank means the host cannot reach any network beyond its local subnet, so internet access is impossible. Option D fails because using the host's own IP (192.168.1.50) as the default gateway would cause the host to attempt to route traffic to itself, never reaching the actual gateway.

What should I do if I get this 200-301 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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Last reviewed: Jun 11, 2026

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