Which of the following is an ip address that is private? (i.e. reserved for internal networks, and not
a valid address to use on the Internet)?

A.
172.5.42.5

B.
172.76.42.5

C.
172.90.42.5

D.
172.16.42.5

Explanation:
The IP address 172.16.42.5 is contained in a class B reserved network, IANA
reserved the 172.16.0.0 through 172.31.255.255 networks for internal use, this network its not
routable in Internet and its commonly used in intranets. Class B networks are used in mediumsized networks. In class B networks, the two high order bits are always 10, and then remaining bits
are used to define 16.384 networks, each with as many as 65.534 hosts attached. Examples of
valid Class B networks include Microsoft and Exxon.