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300-410 Practice Question: Is troubleshooting a router that is not…
A network engineer is troubleshooting a router that is not responding to ICMP echo requests from a management station at 10.10.10.1. The router has an ACL applied to the VTY lines that permits only 10.10.10.0/24. The engineer can telnet to the router from the management station. What is the most likely cause?
⚠ Common exam trap
Cisco often tests the misconception that VTY ACLs control all management traffic, including ICMP, when in fact VTY ACLs only filter Telnet/SSH sessions, while ICMP is filtered by interface ACLs.
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
✓
An inbound ACL on the interface denies ICMP from 10.10.10.1.
The management station can telnet to the router, which proves that the VTY ACL permits 10.10.10.0/24 and that reachability exists. Since ICMP is processed by the interface input path before any VTY ACL, the failure of ICMP echo requests points to an inbound ACL on the interface that explicitly denies ICMP from 10.10.10.1. This is the most likely cause because telnet (TCP/23) succeeds while ICMP fails, isolating the issue to interface-level filtering.
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 VTY ACL also applies to ICMP traffic.
Why it's wrong here
VTY ACLs only control Telnet/SSH access, not ICMP.
- ✓
An inbound ACL on the interface denies ICMP from 10.10.10.1.
Why this is correct
Since Telnet works, the VTY ACL is not the issue; an interface ACL blocking ICMP is the likely cause.
- ✗
The router has 'no ip icmp echo' configured globally.
Why it's wrong here
There is no such global command; ICMP echo responses are controlled by interface ACLs or the 'ip icmp rate-limit' feature.
- ✗
The management station is not in the routing table of the router.
Why it's wrong here
If the management station were not reachable, Telnet would also fail.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 300-410 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 300-410 exam.