mediumMultiple ChoiceObjective-mapped
300-410 Practice Question: Runs the following command on Router R1: R1# show…
A network engineer runs the following command on Router R1:
R1# show ip access-lists
Extended IP access list 120
10 permit tcp 10.0.0.0 0.255.255.255 any eq www (1000 matches)
20 permit udp any any eq dns (500 matches)
30 deny ip any any (200 matches)Based on this output, what is the problem?
⚠ Common exam trap
Cisco often tests the misconception that an ACL with permit statements is automatically 'correct' or 'permissive,' when in fact the explicit deny at the end makes it highly restrictive, and candidates may overlook the need to evaluate whether the ACL matches the intended security policy.
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 is blocking all traffic except web and DNS, which may be too restrictive.
The ACL explicitly permits only TCP port 80 (www) and UDP port 53 (dns) traffic, while the final deny ip any any statement blocks all other traffic. With only 1000 matches for web and 500 for DNS, the ACL is likely too restrictive for a production network, as it would drop essential traffic such as routing protocols, management traffic (e.g., SSH, SNMP), or other application flows. The output shows the ACL is present and has hit counts, but its restrictive nature is the problem.
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 is correctly permitting web and DNS traffic.
Why it's wrong here
While it permits those, the deny all statement may block other needed traffic.
- ✓
The ACL is blocking all traffic except web and DNS, which may be too restrictive.
Why this is correct
The deny ip any any with matches shows that other traffic is being denied, which could be a problem.
- ✗
The ACL has no effect because it is not applied.
Why it's wrong here
The match counts indicate the ACL is applied and active.
- ✗
The ACL allows all traffic because of the permit statements.
Why it's wrong here
The deny ip any any overrides and denies all other traffic.
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.