The answer is the first matching entry in the list is applied. This is because Cisco IOS processes IPv4 ACL entries sequentially from top to bottom, executing the associated permit or deny action as soon as a packet matches a rule, then immediately stopping further evaluation. This first-match rule is fundamental to ACL design and troubleshooting, and on the Cisco CCNP ENARSI 300-410 exam, it tests your ability to predict traffic flow through an ACL and spot misconfigurations. A common trap is assuming a later, more specific entry will override an earlier, broader one—it will not, because the first match wins. To remember this, think of a bouncer at a club: the first rule that fits the person’s description decides their entry, and no other bouncer gets a say.
300-410 IPv4 Access Control Lists Practice Question
This 300-410 practice question tests your understanding of ipv4 access control lists. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
What is the default behavior of an IPv4 ACL regarding the order of evaluation when multiple entries match a packet?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The first matching entry in the list is applied.
Cisco IOS processes IPv4 ACL entries in sequential order, from top to bottom. When a packet matches an entry, the associated permit or deny action is applied immediately, and no further entries are evaluated. This first-match rule is fundamental to ACL design and troubleshooting.
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.
✗
The most specific entry is used regardless of order.
Why it's wrong here
ACLs do not use longest match; they use first match.
✓
The first matching entry in the list is applied.
Why this is correct
Cisco ACLs process entries in order; the first match wins.
Related concept
Read the scenario before looking for a memorised answer.
✗
All matching entries are evaluated and the most permissive action is taken.
Why it's wrong here
Only the first match is used; no aggregation of actions.
✗
The last matching entry in the list overrides earlier ones.
Why it's wrong here
First match wins, not last.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that ACLs use longest-prefix matching like routing tables, but ACLs strictly use first-match order, not specificity.
Detailed technical explanation
How to think about this question
Under the hood, Cisco IOS uses a sequential list structure for ACLs, where each entry is checked in order until a match is found. This is defined in RFC 1700 and implemented in the CEF (Cisco Express Forwarding) switching path, which uses a TCAM (Ternary Content-Addressable Memory) for hardware acceleration, but the logical order is preserved. A common real-world scenario is when a broad deny entry is placed before a specific permit entry, causing unintended traffic drops — a classic ACL design mistake.
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: The first matching entry in the list is applied. — Cisco IOS processes IPv4 ACL entries in sequential order, from top to bottom. When a packet matches an entry, the associated permit or deny action is applied immediately, and no further entries are evaluated. This first-match rule is fundamental to ACL design and troubleshooting.
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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