If a subnet is defined as 10.0.0.0/28, what is the broadcast address?

• A. 10.0.0.15
• B. 10.0.0.0
• C. 10.0.0.1
• D. 10.0.0.16

Answer: (A)

In IPv4, the broadcast address is the address within a subnet where all the host bits are 1. For a /28, the last octet has 4 bits for hosts, giving a range from 0 to 15 in that subnet. The network address uses all host bits as 0 (10.0.0.0). The broadcast uses all host bits as 1 (10.0.0.15). So, 10.0.0.15 is the broadcast address for 10.0.0.0/28. The other addresses serve different roles: 10.0.0.0 is the network address, 10.0.0.1 is a usable host address, and 10.0.0.16 is the next subnet’s network address.