Which of the following security devices can be replicated on a Linux based computer using IP tables to
inspect and properly handle network based traffic?

A.
Sniffer

B.
Router

C.
Firewall

D.
Switch

Explanation:
Ip tables are a user-space application program that allows a system administrator to configure the tables
provided by the Linux kernel firewall and the chains and rules it stores.
Incorrect Answers:
A: A sniffer is a tool used in the process of monitoring the data that is transmitted across a network.
B, D: A router is connected to two or more data lines from different networks, whereas a network switch
is connected to data lines from one single network. These may include a firewall, but not by default.

http://en.wikipedia.org/wiki/Iptables
Dulaney, Emmett and Chuck Eastton, CompTIA Security+ Study Guide, 6th Edition, Sybex, Indianapolis,
2014, p. 342
http://en.wikipedia.org/wiki/Router_(computing)