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200-901 Practice Question: A network administrator is troubleshooting a…
A network administrator is troubleshooting a connectivity issue. A PC with IP address 192.168.1.10/24 cannot ping a server at 192.168.1.20/24. Both are on the same VLAN and connected to the same switch. What is the most likely cause of the issue?
⚠ Common exam trap
Cisco often tests the misconception that same-subnet communication requires a default gateway, or that ARP cache issues are the primary cause of ping failures, when in reality a host firewall blocking ICMP is a frequent real-world problem that candidates overlook.
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 server has a firewall blocking ICMP echo requests.
Since both devices are on the same subnet (192.168.1.0/24) and same VLAN, Layer 2 connectivity should work without a default gateway. The PC can ARP for the server's IP and send frames directly. If the server has a firewall blocking ICMP echo requests (ping), the PC's ARP request succeeds, but the server drops the ICMP packets, causing a ping failure while other services might still work.
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 ARP cache on the PC needs to be cleared.
Why it's wrong here
ARP cache can be cleared, but it is not the most likely cause of persistent failure.
- ✗
The subnet mask on the PC is incorrect.
Why it's wrong here
The /24 mask is correct for the given IP range.
- ✗
The switch port is in the wrong VLAN.
Why it's wrong here
Both are on the same VLAN as stated, so this is not the issue.
- ✓
The server has a firewall blocking ICMP echo requests.
Why this is correct
A firewall can block ping, which is a common troubleshooting scenario.
- ✗
The default gateway is misconfigured on the PC.
Why it's wrong here
Default gateway is not required for communication within the same subnet.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-901 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 200-901 exam.