Question 10
An aggregation switch has a routed SVI for each department. A security requirement permits Finance to reach the shared DNS service but must prevent Finance from initiating connections to Payroll. What additional control does basic inter-VLAN routing lack?
Explanation
Correct Answer
Routing between SVIs provides reachability, but it does not by itself enforce application-specific departmental segmentation. A correctly located extended IPv4 ACL can match source and destination prefixes and protocol or ports, while allowing the approved DNS traffic. Review ACL order and implicit deny and test both permitted and prohibited flows before deployment.
Incorrect Answers
Additional routed interfaces add potential paths but do not create the required selective filter. An explicit forwarding policy is needed when one application is permitted and another forbidden.
Duplicate gateway addressing creates an invalid operational design and does not specify permitted DNS versus blocked Payroll traffic. Packet filtering must implement the security rule.
Without an alternative design, disabling all routing would block the authorized DNS path as well as prohibited Payroll sessions. The requirement is granular policy, not total outage.