The IP Address 172.168.10.1 belongs to _____

• A. Class A
• B. Class B
• C. Class C
• D. Class D

Answer: (B)

The main idea here is how IP address classes are determined by the first octet. The first octet is 172, which falls within 128 to 191, so this is a Class B address. Class B uses a default subnet mask of 255.255.0.0, meaning the network portion includes the first two octets. It’s worth noting that 172.168.10.1 lies in the private address range 172.16.0.0 to 172.31.255.255, so it is a private Class B address, but its class designation remains Class B.