This 200-201 practice question tests your understanding of security concepts. 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.
Exhibit
Refer to the exhibit.
! Output from show access-list 101
! Extended IP access list 101
! 10 permit tcp 192.168.1.0 0.0.0.255 host 10.10.10.10 eq 443
! 20 deny ip any any log
!
An analyst reviews the ACL applied to the outside interface of a router. The analyst notices that traffic from 192.168.1.0/24 to 10.10.10.10 on port 443 is permitted, but all other traffic is denied and logged. Which of the following is a potential security issue with this ACL?
Refer to the exhibit.
! Output from show access-list 101
! Extended IP access list 101
! 10 permit tcp 192.168.1.0 0.0.0.255 host 10.10.10.10 eq 443
! 20 deny ip any any log
!
A
The deny statement with logging may generate excessive logs, potentially masking attacks.
Excessive logging can bury important alerts in noise.
B
The ACL is applied inbound on the outside interface, which could allow external traffic.
Why wrong: The exhibit does not indicate the direction; it just shows the ACL content.
C
The permit statement does not have logging enabled, so traffic is not monitored.
Why wrong: Logging on permit is optional; the issue is the deny log.
D
The ACL allows all traffic from 192.168.1.0/24 to 10.10.10.10 on any port.
Why wrong: It only permits port 443, not all ports.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The deny statement with logging may generate excessive logs, potentially masking attacks.
The ACL has a single permit statement for traffic from 192.168.1.0/24 to 10.10.10.10 on port 443, followed by an implicit deny all that is logged. This means every packet that does not match the permit rule generates a log entry. In a production environment, even normal background noise (e.g., scans, broadcast traffic) can produce thousands of log messages per second, overwhelming syslog storage and masking malicious activity. The core issue is that logging on the deny-all can cause log flooding, not that the permit lacks logging.
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 deny statement with logging may generate excessive logs, potentially masking attacks.
Why this is correct
Excessive logging can bury important alerts in noise.
Related concept
Read the scenario before looking for a memorised answer.
✗
The ACL is applied inbound on the outside interface, which could allow external traffic.
Why it's wrong here
The exhibit does not indicate the direction; it just shows the ACL content.
✗
The permit statement does not have logging enabled, so traffic is not monitored.
Why it's wrong here
Logging on permit is optional; the issue is the deny log.
✗
The ACL allows all traffic from 192.168.1.0/24 to 10.10.10.10 on any port.
Why it's wrong here
It only permits port 443, not all ports.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that logging on a permit statement is necessary for monitoring, when in fact the critical security issue is that logging on a deny-all can cause log flooding that masks real attacks.
Trap categories for this question
Command / output trap
The exhibit does not indicate the direction; it just shows the ACL content.
Detailed technical explanation
How to think about this question
When an ACL has an explicit deny statement with the 'log' keyword (or an implicit deny with logging enabled via 'ip access-list logging'), every denied packet generates a syslog message at the 'informational' level. On a busy edge router, this can produce millions of logs per day, filling disk space and causing legitimate security events to be lost in the noise. In real-world deployments, best practice is to avoid logging on the final deny-all unless specifically troubleshooting, and instead use a dedicated logging server with rate limiting or a separate ACL for logging suspicious 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.
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 Concepts — This question tests Security Concepts — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The deny statement with logging may generate excessive logs, potentially masking attacks. — The ACL has a single permit statement for traffic from 192.168.1.0/24 to 10.10.10.10 on port 443, followed by an implicit deny all that is logged. This means every packet that does not match the permit rule generates a log entry. In a production environment, even normal background noise (e.g., scans, broadcast traffic) can produce thousands of log messages per second, overwhelming syslog storage and masking malicious activity. The core issue is that logging on the deny-all can cause log flooding, not that the permit lacks logging.
What should I do if I get this 200-201 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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