The answer is that ACL 101 filters traffic leaving the interface. This is correct because the `show ip interface` command output explicitly lists “Outgoing access list is 101,” which indicates the access control list is applied to outbound traffic on GigabitEthernet0/1, while the “Inbound access list is not set” confirms no ACL filters incoming traffic. On the Cisco CCNP ENARSI 300-410 exam, this command is a core tool for verifying ACL direction and placement, often used in troubleshooting scenarios where traffic flow is unexpectedly blocked or permitted. A common trap is misreading the output: many candidates assume “outgoing” refers to traffic entering the interface, but it actually means traffic leaving the router through that interface. A reliable memory tip is to think of the interface as a door—an “outgoing” ACL checks what exits, while an “inbound” ACL checks what enters.
300-410 IPv4 Access Control Lists Practice Question
This 300-410 practice question tests your understanding of ipv4 access control lists. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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.
A network engineer runs the following command on Router R1:
R1# show ip interface GigabitEthernet0/1
GigabitEthernet0/1 is up, line protocol is up
Internet address is 10.1.1.1/24
Broadcast address is 255.255.255.255
Address determined by non-volatile memory
MTU is 1500 bytes
Helper address is not set
Directed broadcast forwarding is disabled
Outgoing access list is 101
Inbound access list is not set
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
ACL 101 filters traffic leaving the interface.
The command output shows 'Outgoing access list is 101', which indicates that ACL 101 is applied to filter traffic leaving the GigabitEthernet0/1 interface. This is confirmed by the absence of an 'Inbound access list' entry, meaning no ACL is applied to incoming traffic. Therefore, ACL 101 filters traffic leaving the interface.
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.
✗
ACL 101 filters traffic entering the interface.
Why it's wrong here
The inbound access list is not set, so no ACL filters incoming traffic.
✓
ACL 101 filters traffic leaving the interface.
Why this is correct
The output shows 'Outgoing access list is 101', so traffic exiting is filtered.
Related concept
Read the scenario before looking for a memorised answer.
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between inbound and outbound ACL application by showing only one direction in the output, leading candidates to assume no ACL is applied or that it applies to both directions.
Detailed technical explanation
How to think about this question
The 'show ip interface' command displays ACL application per direction, where 'Outgoing access list' and 'Inbound access list' fields indicate the specific ACLs applied. ACLs are processed sequentially; for an outbound ACL, the router checks the packet against the ACL after the routing decision and before forwarding out the interface. In real-world scenarios, misapplying an ACL to the wrong direction can lead to unintended traffic filtering, such as blocking management traffic when intended to block user traffic.
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 security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 300-410 question in full detail.
IPv4 Access Control Lists — This question tests IPv4 Access Control Lists — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: ACL 101 filters traffic leaving the interface. — The command output shows 'Outgoing access list is 101', which indicates that ACL 101 is applied to filter traffic leaving the GigabitEthernet0/1 interface. This is confirmed by the absence of an 'Inbound access list' entry, meaning no ACL is applied to incoming traffic. Therefore, ACL 101 filters traffic leaving the interface.
What should I do if I get this 300-410 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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