Which of the following is a reason companies implement routers and packet filters?

A.
To provide content filtering

B.
To provide protection that is transparent to users

C.
To provide circuit-level proxy protection

D.
To provide application-level proxy protection

Explanation:
Routers can provide packet filtering through the use of access control
lists (ACLs). These ACLs are compared to incoming and outgoing traffic and only the
packets that are outlined as acceptable are allowed through. Packet filters cannot
provide content filtering because they do not look that deep into the packet, and
they do not provide application or circuit-level proxy protection. They are
transparent to users because when users request to access a resource on the other
side of the router, they do not have to log into that device or do anything special.
The protection takes place without them knowing about it.