If we borrow 3 bits from a Class C network address, how many usable subnets do we create?

If we borrow 3 bits from a Class C network address, how many usable subnets do we create?

• A. 4
• B. 6
• C. 8
• D. 12

Answer: (C)

In a Class C network address, the default subnet mask is 255.255.255.0, which means there are 24 bits for the network portion and 8 bits for the host portion. When you borrow bits from the host portion to create subnets, those borrowed bits increase the number of subnets available. If you borrow 3 bits from the host portion, you are effectively changing the subnet mask from /24 to /27, as you are using 3 additional bits for subnetting. With 3 bits, you can create 2^3 possible combinations, which results in 8 different subnet configurations (0 to 7). However, it's essential to consider that while borrowing bits increases the number of subnets, the usable subnets will be less than the total possible due to the reserved addresses for network and broadcast in each subnet. Nonetheless, the question explicitly asks for the number of created subnets based on borrowed bits, which confirms that 8 total subnets can be established. Therefore, the answer is correct because borrowing 3 bits from the host portion indeed allows for 8 usable subnets for Class C addresses.

In a Class C network address, the default subnet mask is 255.255.255.0, which means there are 24 bits for the network portion and 8 bits for the host portion. When you borrow bits from the host portion to create subnets, those borrowed bits increase the number of subnets available.

If you borrow 3 bits from the host portion, you are effectively changing the subnet mask from /24 to /27, as you are using 3 additional bits for subnetting. With 3 bits, you can create 2^3 possible combinations, which results in 8 different subnet configurations (0 to 7).

However, it's essential to consider that while borrowing bits increases the number of subnets, the usable subnets will be less than the total possible due to the reserved addresses for network and broadcast in each subnet. Nonetheless, the question explicitly asks for the number of created subnets based on borrowed bits, which confirms that 8 total subnets can be established. Therefore, the answer is correct because borrowing 3 bits from the host portion indeed allows for 8 usable subnets for Class C addresses.