In traditional subnetting, which IP class provides the most host bits to borrow for subnet creation?

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

Answer: (B)

When subnetting with classful addressing, you create subnets by borrowing bits from the host portion of the address and adding them to the network portion. The more host bits you have to begin with, the more bits you can borrow to form subnets (while still leaving enough bits to address hosts in each subnet).

Class A networks have 24 bits in the host portion (default mask 255.0.0.0), Class B networks have 16 host bits (default mask 255.255.0.0), and Class C networks have 8 host bits (default mask 255.255.255.0). Because Class A starts with the largest host portion, it provides the greatest potential to borrow bits for subnet creation, enabling many more subnets than the other classes. A multicast class (Class D) isn’t used for typical host addressing or subnetting.

So, the class that offers the most host bits to borrow for subnet creation is Class A.