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300-410 Practice Question: Network management traffic from a monitoring…
Network management traffic from a monitoring server to routers R1, R2, and R3 is being blocked intermittently. The monitoring server uses SNMP and SSH. R1 configuration: access-list 100 permit udp any any eq snmp, access-list
100 permit tcp any any eq 22, access-list 100 deny ip any any, and 'ip access-group 100 in' on the management interface. R2 shows: 'show snmp' indicates SNMP is enabled. R3 shows: 'show ssh' indicates SSH is enabled. The monitoring server can reach R1 but not R2 or R3. What is the root cause?
⚠ Common exam trap
Cisco often tests the misconception that only application-layer protocols (SNMP, SSH) are needed for management, ignoring that ICMP and routing protocols are essential for basic IP reachability and network stability.
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 ACL permits only SNMP and SSH, but blocks other necessary traffic such as ICMP and routing protocol packets, preventing the monitoring server from reaching R2 and R3.
The ACL on R1 permits only SNMP (UDP port 161) and SSH (TCP port 22), but denies all other IP traffic. For the monitoring server to reach R2 and R3, ICMP (for ping/traceroute) and routing protocol packets (e.g., OSPF, EIGRP) are necessary to establish and maintain reachability. Since the ACL blocks these, the server cannot communicate with R2 and R3, even though SNMP and SSH are enabled on those routers.
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 ACL permits only SNMP and SSH, but blocks other necessary traffic such as ICMP and routing protocol packets, preventing the monitoring server from reaching R2 and R3.
Why this is correct
The implicit deny at the end of the ACL blocks all traffic not explicitly permitted, including ICMP echo requests and routing updates, which are needed for end-to-end connectivity.
- ✗
The ACL is applied in the wrong direction; it should be applied outbound to allow traffic from the management interface.
Why it's wrong here
Applying the ACL inbound filters traffic entering the interface; outbound would filter traffic leaving. The direction is correct for filtering incoming management traffic, but the content is insufficient.
- ✗
SNMP and SSH are not enabled on R2 and R3.
Why it's wrong here
The scenario states SNMP is enabled on R2 and SSH on R3.
- ✗
The monitoring server is not in the same subnet as the management interface, so routing is required but blocked by the ACL.
Why it's wrong here
Routing is needed, but the ACL blocks routing updates, which is part of the issue.
Visual reference
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
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JA
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.