A critical function of a firewall is to act as a:

A.
special router that connects the Internet to a LAN.

B.
device for preventing authorized users from accessing the LAN.

C.
server used to connect authorized users to private trusted network resources.

D.
proxy server to increase the speed of access to authorized users.

Explanation:
A firewall is a set of related programs, located at a network gateway server, that protects the
resources of a private network from users of other networks. An enterprise with an intranet that
allows its workers access to the wider Internet installs a firewall to prevent outsiders from accessing
its own private data resources and for controlling the outside resources to which its own users have
access. Basically, a firewall, working closely with a router program, filters all network packets to
determine whether or not to forward them toward their destination. A firewall includes or works with
a proxy server that makes network requests on behalf of workstation users. A firewall is often
installed in a specially designated computer separate from the rest of the network so no incoming
request can get directed to private network resources.