Which subnet mask will Paula use to divide her 192.168.100.0 network into two smaller networks?

To divide the 192.168.100.0 network into two smaller networks, a subnet mask that allows for the creation of at least two subnets is required. In this case, the choice of 255.255.255.128 is the correct subnet mask because it effectively halves the available address space.

When examining the default subnet mask for a Class C network, which is 255.255.255.0, this mask provides one network with 256 IP addresses (0-255). By using 255.255.255.128, the subnet mask is modified to provide two subnets, each offering 128 addresses (0-127 for the first subnet and 128-255 for the second subnet). This means that Paula can create two smaller networks within the original network address.

Using the subnet mask of 255.255.255.128 results in a change from the fourth octet where the last bit is used to differentiate between the two subnets. This is a common practice in subnetting, allowing for efficient use of IP address space while meeting the needs of different network segments.

Choosing a mask like 255.255.255.192 or 255.255.255.240 would provide more subnetting