Question 794 of 1,819
Network Infrastructure and ConnectivityhardMultiple ChoiceObjective-mapped

Quick Answer

The answer is a duplicate IP address conflict on the web server’s subnet. This is correct because when two devices share the IP address 10.1.1.100, the switch’s MAC address table constantly flips between the two MAC addresses, causing packets to reach the legitimate server only intermittently—hence the every-few-seconds timeout pattern. On the CCNA 200-301 v2 exam, this scenario tests your ability to correlate intermittent connectivity with ARP table instability; a common trap is assuming a faulty cable or gateway issue, but the key clue is that local pings succeed while the remote server fails sporadically. Remember the memory tip: “Flip-flop MACs make pings drop”—if a traceroute shows the first hop working but later hops failing unpredictably, always suspect duplicate IP on that subnet.

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.

Network Topology
Interface:0x5C:\Users\User>tracert 10.1.1.100C:\Users\User>arp -aInternet Address Physical Address Type192.168.1.1 00-1a-2b-3c-4d-5e dynamic192.168.1.100 00-1a-2b-3c-4d-5f dynamic192.168.1.200 00-1a-2b-3c-4d-60 dynamicC:\Users\User>ipconfig /allWindows IP ConfigurationEthernet adapter Local Area Connection:

A user reports intermittent connectivity to the corporate web server at 10.1.1.100. The user's PC (IP 192.168.1.50/24, gateway 192.168.1.1) can ping the gateway and other local hosts, but pings to the web server time out every few seconds. The network administrator runs a traceroute from the PC and checks the local ARP cache. What is the most likely cause of the intermittent connectivity?

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

  • Clue: "most likely"

    Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

Question 1hardmultiple choice
Review the full routing breakdown →
Network Topology
Interface:0x5C:\Users\User>tracert 10.1.1.100C:\Users\User>arp -aInternet Address Physical Address Type192.168.1.1 00-1a-2b-3c-4d-5e dynamic192.168.1.100 00-1a-2b-3c-4d-5f dynamic192.168.1.200 00-1a-2b-3c-4d-60 dynamicC:\Users\User>ipconfig /allWindows IP ConfigurationEthernet adapter Local Area Connection:

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 web server at 10.1.1.100 has a duplicate IP address conflict with another device on the same subnet.

The intermittent connectivity and successful pings to the gateway and local hosts, combined with a traceroute that likely shows the first hop succeeding but subsequent hops failing, point to a duplicate IP address conflict on the web server's subnet. When two devices share the same IP address (10.1.1.100), the switch's MAC address table flips between the two MAC addresses, causing packets to reach the correct server only intermittently. This explains why pings time out every few seconds rather than failing consistently.

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.

  • The default gateway 192.168.1.1 is not configured to route traffic to the 10.1.1.0/24 network.

    Why it's wrong here

    The traceroute shows the first hop responds, indicating the gateway is reachable. If the gateway lacked a route, it would likely send an ICMP unreachable message rather than timeouts. The issue is more specific to the ARP confusion.

  • The web server at 10.1.1.100 has a duplicate IP address conflict with another device on the same subnet.

    Why this is correct

    The ARP cache shows an entry for 192.168.1.100, which is the web server's IP but on the wrong subnet (should be 10.1.1.x). This indicates that a device on the local subnet (192.168.1.0/24) is using the IP 192.168.1.100, causing the user's PC to associate the web server's IP with a local MAC address. This leads to intermittent connectivity as the PC may send traffic to the wrong device.

    Clue confirmation

    The clue word "most likely" in the question point toward this answer.

    Related concept

    Read the scenario before looking for a memorised answer.

  • The user's PC has an incorrect subnet mask configured, preventing communication with the web server.

    Why it's wrong here

    The ipconfig /all output shows the correct subnet mask (255.255.255.0) and gateway (192.168.1.1). The PC can reach the gateway, so the subnet mask is not the issue.

  • The web server is powered off or has a faulty network interface card.

    Why it's wrong here

    If the web server were offline, the traceroute would likely show no response from any hop, but the first hop responds. Additionally, the ARP cache shows an entry for 192.168.1.100, indicating that something is responding to ARP requests for that IP, which contradicts a complete hardware failure.

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 web server at 10.1.1.100 has a duplicate IP address conflict with another device on the same subnet.Correct answer

Why this is correct

The ARP cache shows an entry for 192.168.1.100, which is the web server's IP but on the wrong subnet (should be 10.1.1.x). This indicates that a device on the local subnet (192.168.1.0/24) is using the IP 192.168.1.100, causing the user's PC to associate the web server's IP with a local MAC address. This leads to intermittent connectivity as the PC may send traffic to the wrong device.

The default gateway 192.168.1.1 is not configured to route traffic to the 10.1.1.0/24 network.Wrong answer — click to see why

Why this is wrong here

The traceroute shows the first hop (gateway) responds, indicating the gateway is reachable and routing is functioning. If the gateway lacked a route to 10.1.1.0/24, it would typically send an ICMP Destination Unreachable (Network Unreachable) message, not cause intermittent timeouts. The issue is more specific to ARP confusion at the local subnet.

Why candidates choose this

Students may think that a missing route on the gateway would cause connectivity issues, but they overlook that the gateway is reachable and the problem is intermittent, which points to a local ARP issue rather than a routing table problem.

The user's PC has an incorrect subnet mask configured, preventing communication with the web server.Wrong answer — click to see why

Why this is wrong here

The ipconfig /all output shows the correct subnet mask (255.255.255.0) and gateway (192.168.1.1). The PC can ping the gateway and other local hosts, confirming the subnet mask is correct. An incorrect subnet mask would prevent communication with the gateway or local hosts, not just the remote server.

Why candidates choose this

Students often suspect subnet mask issues when a host cannot reach a remote network, but they forget that the PC can already communicate with the gateway, which rules out a subnet mask problem.

The web server is powered off or has a faulty network interface card.Wrong answer — click to see why

Why this is wrong here

If the web server were powered off or had a faulty NIC, the traceroute would likely show no response from any hop beyond the gateway, and the ARP cache would not show an entry for 192.168.1.100. The presence of an ARP entry for that IP indicates that a device is responding to ARP requests, contradicting a complete hardware failure.

Why candidates choose this

Students may assume that a server being offline is a common cause of connectivity issues, but they overlook the ARP evidence that something is responding, and the intermittent nature suggests a conflict rather than a dead server.

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 distinction between consistent failures (e.g., routing misconfiguration or server down) and intermittent failures (e.g., duplicate IP or STP convergence), and the trap here is assuming a routing issue (Option A) when the symptom is intermittent, not constant.

Trap categories for this question

  • Similar concept trap

    The traceroute shows the first hop responds, indicating the gateway is reachable. If the gateway lacked a route, it would likely send an ICMP unreachable message rather than timeouts. The issue is more specific to the ARP confusion.

  • Command / output trap

    The traceroute shows the first hop responds, indicating the gateway is reachable. If the gateway lacked a route, it would likely send an ICMP unreachable message rather than timeouts. The issue is more specific to the ARP confusion.

Detailed technical explanation

How to think about this question

Duplicate IP detection relies on gratuitous ARP (RFC 5227), where a host sends an ARP request for its own IP to check for conflicts. In a real-world scenario, a misconfigured device (e.g., a printer or another server) with the same IP as the web server causes the switch to learn two MAC addresses for the same IP, leading to MAC address table flapping and intermittent reachability. The traceroute output would show the first hop (gateway) responding, but subsequent hops may show varying response times or timeouts as the path oscillates between the two devices.

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.

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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: The web server at 10.1.1.100 has a duplicate IP address conflict with another device on the same subnet. — The intermittent connectivity and successful pings to the gateway and local hosts, combined with a traceroute that likely shows the first hop succeeding but subsequent hops failing, point to a duplicate IP address conflict on the web server's subnet. When two devices share the same IP address (10.1.1.100), the switch's MAC address table flips between the two MAC addresses, causing packets to reach the correct server only intermittently. This explains why pings time out every few seconds rather than failing consistently.

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.

Are there clue words in this question I should notice?

Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

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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