The answer is that both HTTP and HTTPS traffic are permitted to the web server. This is because an ACL is processed top-down, and the first matching rule is applied; while the initial line explicitly permits HTTPS (TCP port 443) to 10.0.0.100, the subsequent “permit ip any any” statement catches all other traffic, including HTTP (TCP port 80), which is not denied by any earlier rule. On the CISA exam, this scenario tests your understanding of implicit deny versus explicit permit logic—a common trap is assuming that a specific permit for HTTPS blocks HTTP by default, but without a deny statement for port 80, the catch-all permit overrides that assumption. Remember the key principle: in an ACL, what is not explicitly denied is implicitly permitted only if a final “permit any” exists; otherwise, an implicit deny blocks everything else. A useful memory tip: “Specific first, then the net—if you permit all, you catch what’s left.”
CISA Practice Question: Information Systems Acquisition, Development and Implementation
This CISA practice question tests your understanding of information systems acquisition, development and implementation. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
SW1(config)# access-list 101 permit tcp any host 10.0.0.100 eq 443
SW1(config)# access-list 101 deny tcp any host 10.0.0.100 eq 80
SW1(config)# access-list 101 permit ip any any
SW1(config)# interface vlan 10
SW1(config-if)# ip access-group 101 in
Refer to the exhibit. An administrator applied this ACL to a VLAN interface. The server at 10.0.0.100 hosts a web application. What is the effect of this ACL?
Refer to the exhibit.
SW1(config)# access-list 101 permit tcp any host 10.0.0.100 eq 443
SW1(config)# access-list 101 deny tcp any host 10.0.0.100 eq 80
SW1(config)# access-list 101 permit ip any any
SW1(config)# interface vlan 10
SW1(config-if)# ip access-group 101 in
A
Allows HTTPS, but HTTP is allowed as well due to the permit ip any any
The permit ip any any overrides the deny.
B
Allows HTTPS, blocks HTTP, and blocks all other traffic
Why wrong: The permit ip any any allows all other traffic.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Allows HTTPS, but HTTP is allowed as well due to the permit ip any any
The ACL shown permits HTTPS (TCP port 443) from any source to the server at 10.0.0.100, and then has a 'permit ip any any' statement at the end. Because ACLs are processed top-down, the first match wins; HTTPS traffic matches the first line and is permitted, while HTTP (TCP port 80) is not explicitly denied, so it matches the 'permit ip any any' line and is also allowed. Thus, both HTTP and HTTPS are permitted, making option A correct.
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.
✓
Allows HTTPS, but HTTP is allowed as well due to the permit ip any any
Why this is correct
The permit ip any any overrides the deny.
Related concept
Read the scenario before looking for a memorised answer.
✗
Allows HTTPS, blocks HTTP, and blocks all other traffic
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often overlook the 'permit ip any any' at the end of the ACL and incorrectly assume that only the explicitly permitted HTTPS traffic is allowed, missing that this catch-all statement permits all other traffic, including HTTP.
Detailed technical explanation
How to think about this question
Cisco ACLs use a first-match-wins logic; once a packet matches a permit or deny statement, no further lines are evaluated. The 'permit ip any any' at the end acts as a catch-all, allowing all traffic that hasn't been explicitly denied earlier. In this ACL, there is no deny statement for HTTP (TCP port 80), so HTTP traffic matches the final permit line and is allowed. This is a common configuration mistake where administrators assume only the explicit permits are allowed, forgetting the implicit deny at the end of every ACL—but here the explicit 'permit ip any any' overrides that implicit deny.
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 help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.
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.
Information Systems Acquisition, Development and Implementation — This question tests Information Systems Acquisition, Development and Implementation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Allows HTTPS, but HTTP is allowed as well due to the permit ip any any — The ACL shown permits HTTPS (TCP port 443) from any source to the server at 10.0.0.100, and then has a 'permit ip any any' statement at the end. Because ACLs are processed top-down, the first match wins; HTTPS traffic matches the first line and is permitted, while HTTP (TCP port 80) is not explicitly denied, so it matches the 'permit ip any any' line and is also allowed. Thus, both HTTP and HTTPS are permitted, making option A correct.
What should I do if I get this CISA 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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