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)?

The correct answer is C. 172.31.42.5. This is a valid Class B reserved address. For Class B networks, the reserved addresses are 172.16.0.0 - 172.31.255.255. The private IP address ranges are defined within RFC 1918: RFC 1918 private ip address range The following answers are incorrect: 172.12.42.5 Is incorrect…

Submitted by helene.fr· Apr 18, 2026Network and Communications Security

Question

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)?

Exhibit

Options

A172.12.42.5
B172.140.42.5
C172.31.42.5
D172.15.42.5

How the community answered

(20 responses)

B
5% (1)
C
85% (17)
D
10% (2)

Explanation

This is a valid Class B reserved address. For Class B networks, the reserved addresses are 172.16.0.0 - 172.31.255.255. The private IP address ranges are defined within RFC 1918: RFC 1918 private ip address range The following answers are incorrect: 172.12.42.5 Is incorrect because it is not a Class B reserved address. 172.140.42.5 Is incorrect because it is not a Class B reserved address. 172.15.42.5 Is incorrect because it is not a Class B reserved address.

Topics

#Private IP addresses#RFC 1918#IP addressing#Network segmentation

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