Which 32-bit value divides an IP address into network and host portions?

• A. Subnet Mask
• B. IP Address
• C. Broadcast Address
• D. Gateway

Answer: (A)

Think about how an IPv4 address is used to separate which part identifies the network and which part identifies the specific device on that network. The tool that does this separation is the subnet mask. It’s a 32-bit value where 1s mark the network bits and 0s mark the host bits. When you apply the mask to the IP address (using a bitwise AND), the result gives the network address, while the remaining bits form the host address within that network. For example, with 192.168.1.10 and a 255.255.255.0 mask (a /24), the network is 192.168.1.0 and the host part is 0.0.0.10. The other items aren’t used to divide the address into network and host parts: the IP address itself is the thing being divided, the broadcast address is used to reach all hosts on a network, and the gateway is the router’s address used to reach other networks.