While examining excessive traffic on the network, it is noted that all incoming packets on an interface appear to be allowed even though an IPv4 ACL is applied to the interface.
Which two misconfigurations cause this behavior? (Choose two.)
Click on the arrows to vote for the correct answer
A. B. C. D. E.BE.
When an IPv4 ACL is applied to an interface on a Cisco device, it is used to filter incoming packets based on specific criteria defined in the ACL. ACLs can be used to permit or deny traffic based on factors such as source and destination IP addresses, protocol type, and port number.
If all incoming packets on an interface appear to be allowed even though an IPv4 ACL is applied to the interface, this suggests that the ACL is not functioning correctly. There are several possible misconfigurations that could cause this behavior, but two of the most common are:
B. A matching permit statement is too broadly defined: When a permit statement in an ACL is too broadly defined, it can match more traffic than intended. For example, a permit statement that allows traffic from any source IP address to any destination IP address on any port would allow all traffic to pass through the interface, regardless of whether it should be filtered by the ACL.
E. A matching permit statement is too high in the access list: When a permit statement is placed too high in the access list, it can override other statements in the list. This can result in traffic being allowed even if it should be denied by a later statement in the ACL. For example, if a permit statement that allows traffic from a specific source IP address is placed before a deny statement that blocks traffic to that same address, the traffic would be permitted instead of denied.
The other options are also possible misconfigurations, but do not directly result in all incoming packets being allowed through the interface.
A. The ACL is empty: If the ACL is empty, it will not match any traffic and all traffic will be allowed through the interface.
C. The packets fail to match any permit statement: If the packets do not match any permit statements in the ACL, they will be denied by default.
D. A matching deny statement is too high in the access list: When a deny statement is placed too high in the access list, it can override other statements in the list. This can result in traffic being denied even if it should be allowed by a later statement in the ACL.