If you have a /24 network 10.0.0.0/24, how many usable hosts are available and what is the maximum number of subnets you can create using a /28 subnetting within that /24?

If you have a /24 network 10.0.0.0/24, how many usable hosts are available and what is the maximum number of subnets you can create using a /28 subnetting within that /24?

• A. Usable hosts: 254. Subnets with /28: 16 subnets
• B. Usable hosts: 256. Subnets with /28: 8 subnets
• C. Usable hosts: 200. Subnets with /28: 64 subnets
• D. Usable hosts: 254. Subnets with /28: 32 subnets

Answer: (A)

A /24 network has 256 addresses. The network address and the broadcast address cannot be assigned to hosts, so there are 254 usable hosts in 10.0.0.0/24. Subdividing into /28 subnets means borrowing 4 bits from the host portion (28 − 24 = 4), yielding 2^4 = 16 subnets. Each /28 subnet has 16 addresses, with 2 reserved for network and broadcast, giving 14 usable hosts per subnet. Since the question asks for the maximum number of subnets, you can create 16 subnets within the /24. So the correct result is 254 usable hosts and 16 subnets.

A /24 network has 256 addresses. The network address and the broadcast address cannot be assigned to hosts, so there are 254 usable hosts in 10.0.0.0/24.

Subdividing into /28 subnets means borrowing 4 bits from the host portion (28 − 24 = 4), yielding 2^4 = 16 subnets. Each /28 subnet has 16 addresses, with 2 reserved for network and broadcast, giving 14 usable hosts per subnet. Since the question asks for the maximum number of subnets, you can create 16 subnets within the /24.

So the correct result is 254 usable hosts and 16 subnets.