Question

A network administrator configures an ACL on a router interface to permit HTTP and HTTPS traffic from the guest VLAN to a specific web server. After applying the ACL, guest users report they can no longer reach the DNS server or any other internal resources, even though no explicit deny statement was written for those. What is the MOST likely cause of this behavior?

Accepted Answer

The implicit deny at the end of the ACL blocks all traffic not explicitly permitted

Answer

The ACL was applied in the wrong direction on the interface

Answer

The router requires a separate ACL for UDP traffic like DNS

Answer

The permit statements overlap and cancel each other out