The correct answer is that the packet is denied because rule 1 matches and denies it. This outcome hinges on the firewall first match rule evaluation logic, where a firewall processes rules from top to bottom and applies the action of the first rule that matches the packet’s source and destination. Since rule 1 covers source IP 10.0.0.1 within the 10.0.0.0/8 range and destination 192.168.1.1 within 192.168.1.0/24, and its action is ‘deny’, the packet is immediately dropped—no subsequent rules are ever checked. On the ISC2 Certified in Cybersecurity CC exam, this concept tests your understanding of stateless and stateful firewall rule ordering, often appearing in scenario-based questions where a later rule would allow the traffic. A common trap is assuming the firewall will “fall through” to a permissive rule, but first-match logic stops at the first hit. Remember the mnemonic: “First match, final act—once it hits, it’s a fact.”
ISC2 CC Security Operations Practice Question
This CC practice question tests your understanding of security operations. Compare every option against the stated constraints before choosing — the best answer satisfies all requirements, not just the most obvious one. 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.
Exhibit
rule deny any 10.0.0.0/8 log
rule permit any 10.0.0.0/8 any
rule deny any any log
Refer to the exhibit. A firewall rule set is shown (first match applies). An analyst reviews these rules. Which of the following best describes the traffic outcome for a packet from source IP 10.0.0.1 to destination 192.168.1.1?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The packet is denied because rule 1 matches and denies it.
Rule 1 matches the source IP 10.0.0.1 (which falls within the 10.0.0.0/8 range) and the destination 192.168.1.1 (within 192.168.1.0/24), and since the action is 'deny', the packet is denied immediately. Firewalls using 'first match applies' logic stop processing as soon as a matching rule is found, so subsequent rules are never evaluated. Therefore, the correct outcome is denial.
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 packet is permitted because the last rule permits any any.
Why it's wrong here
The last rule denies any any, not permits; also, earlier match prevents further processing.
✓
The packet is denied because rule 1 matches and denies it.
Why this is correct
First-match logic: rule 1 matches and denies before rule 2 can permit.
Clue confirmation
The clue words "best", "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The packet is permitted because rule 2 explicitly permits the traffic.
Why it's wrong here
Rule 2 is never reached because rule 1 already matched.
✗
The packet is denied because there is no explicit permit for 10.0.0.0/8 to 192.168.1.0/24.
Why it's wrong here
Rule 2 permits all traffic from 10.0.0.0/8 to any, but rule 1 overrides.
Common exam traps
Common exam trap: answer the scenario, not the keyword
ISC2 often tests the 'first match applies' concept by placing a broad deny rule early in the rule set, leading candidates to incorrectly assume that a later permit rule will override it, when in fact the packet is denied immediately upon the first match.
Detailed technical explanation
How to think about this question
Cisco ASA and IOS firewalls implement a 'first match' (top-down) rule evaluation model, where the action (permit or deny) is applied immediately upon the first rule that matches all specified fields (source, destination, protocol, ports). This is distinct from 'last match' or 'implicit deny' models; the implicit deny at the end of the rule set only applies if no explicit rule matches. In real-world scenarios, misordering rules (e.g., placing a broad deny before a specific permit) is a common misconfiguration that leads to unintended traffic blocking.
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 analyst at a medium-sized enterprise encounters this scenario during an investigation or architecture review. The correct answer reflects best practice for the specific threat or control described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Security exam questions test whether you can match controls to threats in context — not just recall definitions.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CC question in full detail.
Security Operations — This question tests Security Operations — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The packet is denied because rule 1 matches and denies it. — Rule 1 matches the source IP 10.0.0.1 (which falls within the 10.0.0.0/8 range) and the destination 192.168.1.1 (within 192.168.1.0/24), and since the action is 'deny', the packet is denied immediately. Firewalls using 'first match applies' logic stop processing as soon as a matching rule is found, so subsequent rules are never evaluated. Therefore, the correct outcome is denial.
What should I do if I get this CC question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "best", "first". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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