- A
The host can reach only local subnet destinations because it lacks a next hop for remote networks
This is correct because without a default gateway, the host has no normal path for off-subnet traffic.
- B
The host automatically uses ARP to reach all Internet destinations directly
Why wrong: This is wrong because ARP is a local-link mechanism and does not resolve remote Internet hosts across routers.
- C
The subnet mask alone should be enough to reach all networks
Why wrong: This is wrong because the mask identifies local scope but does not provide a path to remote networks.
- D
The host can still reach Internet destinations if proxy ARP is enabled on the router.
Why wrong: This is wrong because host gateway settings have nothing to do with switchport trunking.
Quick Answer
The answer is that the host can reach only local subnet destinations because it lacks a next hop for remote networks. Without a default gateway, the host has no routing entry to forward packets destined beyond its own subnet, so any traffic for the Internet is simply dropped at the local interface. This tests your understanding of the fundamental role of a default gateway as the next-hop router for off-subnet communication, a core concept in the CCNA 200-301 v2 exam’s IP connectivity section. A common trap is assuming a valid IP and subnet mask alone enable Internet access, but they only define the local network boundary. Remember the mnemonic: “No gateway, no getaway”—without a route out, you’re stuck in your own subnet.
CCNA Network Services and Security Practice Question
This 200-301 practice question tests your understanding of network services and security. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. A key principle to apply: a host uses its subnet mask to determine whether a destination IP address is local or remote based on network boundaries.. 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 host can reach local devices but cannot reach the Internet. The host has a correct IP address and subnet mask, but no default gateway. What is the best explanation?
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 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
The host can reach only local subnet destinations because it lacks a next hop for remote networks
The host can communicate only within its own local subnet because it lacks the next-hop information needed for off-subnet traffic. A valid IP address and subnet mask are not enough by themselves when the destination lies on another network. Option D is incorrect because proxy ARP, while it may allow some off-subnet reachability in specific scenarios, is not a reliable replacement for a default gateway and does not enable general Internet access.
Key principle: A host uses its subnet mask to determine whether a destination IP address is local or remote based on network boundaries.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The host can reach only local subnet destinations because it lacks a next hop for remote networks
Why this is correct
This is correct because without a default gateway, the host has no normal path for off-subnet traffic.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
A host uses its subnet mask to determine whether a destination IP address is local or remote based on network boundaries.
- ✗
The host automatically uses ARP to reach all Internet destinations directly
Why it's wrong here
This is wrong because ARP is a local-link mechanism and does not resolve remote Internet hosts across routers.
When this WOULD be correct
In a different scenario, if the question stated that the host was configured to communicate with devices on the same local network and the question focused on local communication protocols, then it could be correct to say that ARP is used to reach all local devices directly without needing a gateway.
- ✗
The subnet mask alone should be enough to reach all networks
Why it's wrong here
This is wrong because the mask identifies local scope but does not provide a path to remote networks.
When this WOULD be correct
In a question where the context is about a host configured with a static route that explicitly allows communication to all networks based on the subnet mask alone, this option could be correct. For example, if the question stated that the host was part of a specialized network where routing decisions are solely based on subnet masks without needing a gateway.
- ✗
The host can still reach Internet destinations if proxy ARP is enabled on the router.
Why it's wrong here
This is wrong because host gateway settings have nothing to do with switchport trunking.
When this WOULD be correct
In a question about VLAN configurations where a host is incorrectly set to trunking mode instead of access mode, option D would be correct. It would explain why the host cannot communicate with devices on different VLANs due to misconfiguration.
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.
✓The host can reach only local subnet destinations because it lacks a next hop for remote networksCorrect answer▾
Why this is correct
This is correct because without a default gateway, the host has no normal path for off-subnet traffic.
✗The host automatically uses ARP to reach all Internet destinations directlyWrong answer — click to see why▾
Why this is wrong here
ARP is used to resolve IP addresses to MAC addresses within the same local network. It cannot resolve IP addresses on remote networks because routers are required to forward traffic between subnets.
★ When this WOULD be the correct answer
In a different scenario, if the question stated that the host was configured to communicate with devices on the same local network and the question focused on local communication protocols, then it could be correct to say that ARP is used to reach all local devices directly without needing a gateway.
Why candidates choose this
Students may confuse ARP with routing, thinking that ARP can somehow provide a path to any destination, but ARP only works on the local link.
✗The subnet mask alone should be enough to reach all networksWrong answer — click to see why▾
Why this is wrong here
The subnet mask defines which part of an IP address is the network portion, but it does not provide a path to remote networks. A default gateway or a routing table entry is needed for off-subnet communication.
★ When this WOULD be the correct answer
In a question where the context is about a host configured with a static route that explicitly allows communication to all networks based on the subnet mask alone, this option could be correct. For example, if the question stated that the host was part of a specialized network where routing decisions are solely based on subnet masks without needing a gateway.
Why candidates choose this
Some learners might think that the subnet mask alone can determine reachability, but it only helps identify local vs. remote destinations, not how to reach them.
✗The host can still reach Internet destinations if proxy ARP is enabled on the router.Wrong answer — click to see why▾
Why this is wrong here
Proxy ARP is not a substitute for a default gateway; it only works for specific destinations and is not a reliable method for general Internet access.
★ When this WOULD be the correct answer
In a question about VLAN configurations where a host is incorrectly set to trunking mode instead of access mode, option D would be correct. It would explain why the host cannot communicate with devices on different VLANs due to misconfiguration.
Why candidates choose this
The term 'trunking' might be confused with 'trunk' in routing contexts, but here it is a switch feature unrelated to host gateway settings.
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
A frequent exam trap is to think that the subnet mask alone enables a host to reach all networks. Candidates may incorrectly believe that ARP or other mechanisms can resolve remote IP addresses without a default gateway. This mistake overlooks the fact that ARP operates only on the local subnet and cannot resolve IP addresses beyond it. Without a default gateway, the host has no next-hop router to forward off-subnet traffic, so it cannot reach Internet destinations or other remote networks. Understanding this limitation is crucial to avoid selecting incorrect answers that confuse local address resolution with routing.
Detailed technical explanation
How to think about this question
A host on a network uses its IP address and subnet mask to determine which devices are local (on the same subnet) and which are remote (on different subnets). The subnet mask defines the network boundary, allowing the host to identify if a destination IP address is within its local subnet or outside it. For local destinations, the host sends frames directly using MAC addresses resolved by ARP. For remote destinations, the host must forward packets to a router, known as the default gateway, which routes traffic beyond the local subnet. The default gateway is a critical configuration on a host because it provides the next-hop IP address for all traffic destined outside the local subnet. Without a default gateway, the host cannot forward packets to remote networks, including the Internet. Even if the host has a correct IP address and subnet mask, it will only communicate within its local subnet. The host relies on the default gateway to route traffic to other subnets or external networks, making it essential for inter-network communication. A common exam trap is assuming that having a correct IP address and subnet mask alone allows full network connectivity. In reality, the absence of a default gateway restricts the host to local subnet communication only. Practically, this means the host can communicate with devices on the same subnet but cannot reach any device beyond it, including Internet hosts. This behavior is fundamental in Cisco networking and is frequently tested in CCNA exams to assess understanding of basic IP routing and host configuration.
KKey Concepts to Remember
- A host uses its subnet mask to determine whether a destination IP address is local or remote based on network boundaries.
- The default gateway is the next-hop router IP address that a host uses to send packets destined for remote networks.
- Without a default gateway, a host can communicate only with devices on the same local subnet and cannot reach external networks.
- ARP resolves MAC addresses only for devices within the local subnet and cannot resolve addresses beyond the local network.
- A correct IP address and subnet mask are necessary but not sufficient for Internet connectivity without a default gateway.
- The default gateway setting on a host enables routing of off-subnet traffic by directing packets to a router.
- Hosts rely on the default gateway to forward traffic to remote destinations, including the Internet, beyond the local subnet.
- Misunderstanding the role of the default gateway often leads to incorrect assumptions about host connectivity in exams.
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
A host uses its subnet mask to determine whether a destination IP address is local or remote based on network boundaries.
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.
What to study next
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FAQ
Questions learners often ask
What does this 200-301 question test?
Network Services and Security — This question tests Network Services and Security — A host uses its subnet mask to determine whether a destination IP address is local or remote based on network boundaries..
What is the correct answer to this question?
The correct answer is: The host can reach only local subnet destinations because it lacks a next hop for remote networks — The host can communicate only within its own local subnet because it lacks the next-hop information needed for off-subnet traffic. A valid IP address and subnet mask are not enough by themselves when the destination lies on another network. Option D is incorrect because proxy ARP, while it may allow some off-subnet reachability in specific scenarios, is not a reliable replacement for a default gateway and does not enable general Internet access.
What should I do if I get this 200-301 question wrong?
Review a host uses its subnet mask to determine whether a destination IP address is local or remote based on network boundaries., then practise related 200-301 questions on the same topic to reinforce the concept.
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?
A host uses its subnet mask to determine whether a destination IP address is local or remote based on network boundaries.
About these practice questions
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Same concept, more angles
1 more ways this is tested on 200-301
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A host can reach other devices on its local subnet, but it cannot reach remote networks. The host has a valid IP address and subnet mask. Which missing item is the strongest suspect?
medium- ✓ A.Default gateway information
- B.STP priority information
- C.A voice VLAN setting
- D.An OSPF process ID
Why A: The strongest suspect is a missing default gateway. In practical terms, the host can still identify and reach local addresses because it has its own IP and subnet mask. But without a default gateway, it has no next hop for destinations outside the local subnet. That is why local communication works while remote communication fails. This is one of the most common host-configuration troubleshooting patterns on the exam and in real networks.
Last reviewed: May 17, 2026
This 200-301 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 200-301 exam.
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