Which of the following IP addresses are recommended for private networks? (Choose all that apply.)
a. IP addresses that begin with 10 as their first octet
b. IP addresses that begin with 172 as their first octet
c. IP addresses that begin with 192.168 as their first two octets
d. IP addresses that begin with 192 as their first octet
The correct answer and explanation is :
The correct IP addresses recommended for private networks are:
a. IP addresses that begin with 10 as their first octet
b. IP addresses that begin with 172 as their first octet
c. IP addresses that begin with 192.168 as their first two octets
Explanation:
Private IP addresses are a set of IP addresses reserved for internal use within private networks, meaning they are not routable on the public internet. These addresses are defined by the Internet Engineering Task Force (IETF) in RFC 1918. The purpose of private IP addresses is to allow devices within a local network (like a home or enterprise network) to communicate without using public IP addresses, which helps conserve the limited pool of public IP addresses.
Private IP address ranges are allocated as follows:
- 10.0.0.0 to 10.255.255.255 (Class A):
- This range includes all IP addresses that begin with 10 as their first octet. It provides a large number of addresses (over 16 million) suitable for very large networks.
- Example: 10.1.1.1
- 172.16.0.0 to 172.31.255.255 (Class B):
- This range includes addresses starting with 172 in the first octet but limits the second octet to values between 16 and 31. It offers a moderate range of IP addresses (around 1 million) suitable for medium-sized networks.
- Example: 172.20.10.5
- 192.168.0.0 to 192.168.255.255 (Class C):
- This range is more commonly used in smaller networks, such as home networks. It includes IP addresses starting with 192.168 as the first two octets, providing 65,536 addresses.
- Example: 192.168.1.1
Why the other option is incorrect:
d. IP addresses that begin with 192 as their first octet are not specifically recommended for private networks because this does not exclusively refer to the private IP range. The 192.x.x.x range encompasses both private and public IP addresses. Specifically, only the 192.168.x.x range is designated for private use, not all addresses starting with 192. For example, 192.0.2.0/24 is a reserved block for documentation purposes, not for private use.
In summary, the a, b, and c options are part of the private IP address space defined by RFC 1918, while d is not specific enough to guarantee a private address.