N10-005 · Question #625
Which of the following is the default subnet mask for a Class B address?
The correct answer is B. 255.255.0.0. Class B IP addresses (128.0.0.0 to 191.255.255.255) use a default subnet mask of 255.255.0.0, reserving the first two octets for the network and the last two for hosts.
Question
Which of the following is the default subnet mask for a Class B address?
Options
- A255.0.0.0
- B255.255.0.0
- C255.255.255.0
- D255.255.255.255
How the community answered
(16 responses)- B94% (15)
- D6% (1)
Why each option
Class B IP addresses (128.0.0.0 to 191.255.255.255) use a default subnet mask of 255.255.0.0, reserving the first two octets for the network and the last two for hosts.
255.0.0.0 is the default subnet mask for Class A addresses (1.0.0.0 to 126.255.255.255), which use only the first octet for the network portion.
In classful IP addressing, Class B addresses use the first two octets (16 bits) to identify the network, giving a default mask of 255.255.0.0 (/16). This allows each Class B network to support up to 65,534 hosts. Class B addresses are in the range 128.0.0.0 to 191.255.255.255.
255.255.255.0 is the default subnet mask for Class C addresses (192.0.0.0 to 223.255.255.255), which use the first three octets for the network portion.
255.255.255.255 is a host route mask used to identify a single specific host address, not a default classful network mask for any address class.
Concept tested: Classful IP addressing default subnet mask for Class B
Source: https://learn.microsoft.com/en-us/troubleshoot/windows-client/networking/tcpip-addressing-and-subnetting
Topics
Community Discussion
No community discussion yet for this question.