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.
Which statement best explains why a host may still fail even when the DNS server is correct, if the default gateway is wrong?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Because name resolution can succeed while remote forwarding still fails due to the wrong gateway.
A correct DNS server alone does not provide packet forwarding to remote networks. In practical terms, name resolution may succeed, but the host still needs the correct default gateway to reach destinations outside the local subnet. If the gateway is wrong, the host may know the right IP address and still fail to connect.
This is a useful host-troubleshooting reasoning question because it separates naming from forwarding.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Because name resolution can succeed while remote forwarding still fails due to the wrong gateway.
Why this is correct
This is correct because DNS and default gateway serve different parts of the connectivity path.
Clue confirmation
The clue word "best" in the question point toward this answer.
Because DNS automatically replaces the need for any gateway.
Why it's wrong here
This is wrong because DNS does not forward packets.
When this WOULD be correct
In a different question setup, if the question asked about scenarios where DNS could function independently of a gateway, option B would be correct. For example, if the question focused on local name resolution within a single subnet without external traffic, then DNS could theoretically operate without a gateway.
✗
Because a wrong gateway changes the hostname of the server.
Why it's wrong here
This is wrong because gateway configuration does not alter hostnames.
When this WOULD be correct
In a different question context, if the question asked about the impact of incorrect network configurations on hostname resolution, option C could be correct if it specified a scenario where a misconfigured DNS server alters the perceived hostname for a client, leading to confusion about the server's identity.
✗
Because hosts use the default gateway only for local traffic.
Why it's wrong here
This is wrong because the default gateway is for off-subnet traffic.
When this WOULD be correct
In a different question that states, 'What is the role of a default gateway in a local network?' option D could be correct if it emphasizes that the gateway is primarily used for local traffic routing, implying that local communication does not require it.
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.
✓Because name resolution can succeed while remote forwarding still fails due to the wrong gateway.Correct answer▾
Why this is correct
This is correct because DNS and default gateway serve different parts of the connectivity path.
✗Because DNS automatically replaces the need for any gateway.Wrong answer — click to see why▾
Why this is wrong here
This option is incorrect because DNS does not replace the need for a gateway; it only resolves domain names to IP addresses. A host still requires a correct default gateway to route traffic outside its local network, regardless of DNS functionality.
★ When this WOULD be the correct answer
In a different question setup, if the question asked about scenarios where DNS could function independently of a gateway, option B would be correct. For example, if the question focused on local name resolution within a single subnet without external traffic, then DNS could theoretically operate without a gateway.
Why candidates choose this
Candidates may choose this option due to a misunderstanding of how DNS and networking work together, mistakenly believing that DNS resolution alone is sufficient for all network communication.
✗Because a wrong gateway changes the hostname of the server.Wrong answer — click to see why▾
Why this is wrong here
This option is incorrect because a wrong default gateway does not change the hostname of a server; it affects the routing of packets to and from the host. The hostname remains unchanged regardless of the gateway configuration.
★ When this WOULD be the correct answer
In a different question context, if the question asked about the impact of incorrect network configurations on hostname resolution, option C could be correct if it specified a scenario where a misconfigured DNS server alters the perceived hostname for a client, leading to confusion about the server's identity.
Why candidates choose this
Candidates may choose this option due to a misunderstanding of how network configurations interact; they might incorrectly believe that gateway settings can directly alter hostnames, leading to confusion about network functionality.
✗Because hosts use the default gateway only for local traffic.Wrong answer — click to see why▾
Why this is wrong here
This option is incorrect because the default gateway is essential for routing traffic beyond the local network, not just for local traffic. A wrong gateway would prevent any traffic from reaching remote destinations, regardless of whether it is local or not.
★ When this WOULD be the correct answer
In a different question that states, 'What is the role of a default gateway in a local network?' option D could be correct if it emphasizes that the gateway is primarily used for local traffic routing, implying that local communication does not require it.
Why candidates choose this
Candidates may choose this option due to a misunderstanding of network routing concepts, believing that the default gateway is only relevant for local communications and not recognizing its critical role in remote traffic management.
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: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Detailed technical explanation
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
CIDR notation defines the prefix length.
Block size helps identify subnet boundaries.
Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
The required host count determines the smallest suitable subnet.
TExam Day Tips
→Write the block size before choosing the subnet.
→Check whether the question asks for hosts, subnets or a specific address range.
→Do not confuse /24, /25, /26 and /27 host counts.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 200-301 question in full detail.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related 200-301 subnetting questions on CIDR, address ranges, and subnet selection.
Network Infrastructure and Connectivity — This question tests Network Infrastructure and Connectivity — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Because name resolution can succeed while remote forwarding still fails due to the wrong gateway. — A correct DNS server alone does not provide packet forwarding to remote networks. In practical terms, name resolution may succeed, but the host still needs the correct default gateway to reach destinations outside the local subnet. If the gateway is wrong, the host may know the right IP address and still fail to connect.
This is a useful host-troubleshooting reasoning question because it separates naming from forwarding.
What should I do if I get this 200-301 question wrong?
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related 200-301 subnetting questions on CIDR, address ranges, and subnet selection.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
CIDR notation defines the prefix length.
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