300-410 Question 216
Single answerA network administrator has configured the following time-based IPv4 ACL on a Cisco router:
access-list 101 permit tcp any any eq 80 time-range WORK_HOURS
time-range WORK_HOURS
periodic weekdays 09:00 to 17:00
The administrator wants to ensure that HTTP traffic is only allowed during working hours (Monday to Friday, 9 AM to 5 PM). However, after applying this ACL to the interface, HTTP traffic is still being allowed outside of the specified hours. What could be the possible cause?
- A
The ACL is not correctly applied to the desired interface.
- B
The time-range WORK_HOURS is incorrectly configured with overlapping hours.
- C
The system clock on the router is not synchronized or set to the correct time.
- D
Time-based ACLs do not support the 'periodic' keyword.
Show answer and explanation
Correct answer: C
Explanation
Time-based ACLs rely on the router's system clock to enforce time restrictions. If the router’s clock is not synchronized correctly or set to the wrong time, the ACL will not behave as expected. In this scenario, the most likely issue is that the system clock is not set correctly, causing the ACL to allow HTTP traffic outside of the specified WORK_HOURS time range.
- A. Incorrect.
This is a valid reason why the ACL might not work as expected, but the question does not indicate whether the ACL was applied or not. The issue described is more likely related to time configuration.
- B. Incorrect.
The time-range configuration is correct, as 'weekdays 09:00 to 17:00' is a valid configuration and does not cause overlapping hours.
- C. Correct.
If the system clock on the router is not synchronized or set correctly, the time-based ACL will not function as intended, leading to issues such as allowing traffic outside the specified time range.
- D. Incorrect.
Time-based ACLs do support the 'periodic' keyword, making this option incorrect.