The answer is that the connection is denied by Rule 1. This occurs because ACLs are processed top-down, and the first matching rule determines the action; Rule 1 denies all traffic from the 10.0.1.0/24 subnet to the 10.0.2.0/24 subnet, and since the host at 10.0.1.5 and the server at 10.0.2.10 fall within those ranges, the SSH attempt is blocked immediately, regardless of any permissive rules listed later. On the CompTIA SecurityX CAS-004 exam, this concept tests your understanding of ACL rule order and the critical principle that once a match is found, processing stops—a common trap is assuming a more specific rule later in the list will override an earlier broad deny. Remember the memory tip: "First match wins, so order your denies before your permits."
CAS-004 Security Engineering Practice Question
This CAS-004 practice question tests your understanding of security engineering. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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
Refer to the exhibit.
Exhibit:
```
Filtering rules for interface eth0 (direction inbound):
Rule 1: deny tcp 10.0.1.0/24 any eq 22
Rule 2: permit tcp any host 10.0.1.10 eq 443
Rule 3: deny ip any 10.0.2.0/24
Rule 4: permit tcp 10.0.1.0/24 host 10.0.2.10 eq 3306
Rule 5: deny ip any any
```
A security analyst reviews the ACL rules above. A host at 10.0.1.5 attempts to SSH (port 22) to a server at 10.0.2.10. What is the result?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The connection is denied by Rule 1.
Rule 1 denies all traffic from 10.0.1.0/24 to 10.0.2.0/24. Since the source (10.0.1.5) and destination (10.0.2.10) fall within these subnets, the SSH attempt is denied by Rule 1, regardless of any later rules. ACLs are processed top-down, and the first matching rule determines the action.
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 connection is denied by Rule 3.
Why it's wrong here
Rule 3 denies all IP from any to 10.0.2.0/24, but Rule 1 matches first.
The connection is permitted by the implicit permit.
Why it's wrong here
There is an implicit deny at the end, not permit.
✓
The connection is denied by Rule 1.
Why this is correct
Rule 1 explicitly denies SSH from the 10.0.1.0/24 subnet.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the first-match principle in ACLs, where candidates mistakenly think a later permit rule (like Rule 3 or 4) can override an earlier deny rule, but the order of evaluation is sequential and stops at the first match.
Detailed technical explanation
How to think about this question
Cisco ACLs use first-match logic: once a rule matches, no further rules are evaluated. The implicit deny at the end of every ACL (deny ip any any) ensures that unmatched traffic is dropped, which is a security best practice. In this scenario, Rule 1 matches the source/destination subnets and denies all IP traffic, including SSH, before any permit rules for specific ports are reached.
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 small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Security Engineering — This question tests Security Engineering — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The connection is denied by Rule 1. — Rule 1 denies all traffic from 10.0.1.0/24 to 10.0.2.0/24. Since the source (10.0.1.5) and destination (10.0.2.10) fall within these subnets, the SSH attempt is denied by Rule 1, regardless of any later rules. ACLs are processed top-down, and the first matching rule determines the action.
What should I do if I get this CAS-004 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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