Users are unable to connect to the web server at IP 192.168.0.20. Which of the following can be
inferred of a firewall that is configured ONLY with the following ACL?
PERMIT TCP ANY HOST 192.168.0.10 EQ 80
PERMIT TCP ANY HOST 192.168.0.10 EQ 443

A.
It implements stateful packet filtering.

B.
It implements bottom-up processing.

C.
It failed closed.

D.
It implements an implicit deny.

Explanation:
Implicit deny is the default security stance that says if you aren’t specifically granted access or
privileges for a resource, you’re denied access by default. Implicit deny is the default response
when an explicit allow or deny isn’t present.