What subnet mask is required for an IPv4 network that needs to accommodate 40 devices without wasting address space?

What subnet mask is required for an IPv4 network that needs to accommodate 40 devices without wasting address space?

• A. 255.255.255.128
• B. 255.255.255.192
• C. 255.255.255.0
• D. 255.255.255.240

Answer: (B)

To determine the correct subnet mask for accommodating 40 devices, it is essential to consider how subnetting works in terms of available host addresses. Each subnet mask divides the IP address space into a certain number of subnets and hosts. A subnet mask of 255.255.255.192 provides a block of 64 IP addresses (2^6 = 64), since the last octet allows for 6 bits to determine the hosts. Out of these 64 addresses, 2 are reserved: one for the network address and one for the broadcast address, leaving 62 usable addresses. This is more than sufficient, as it fits the requirement for 40 devices for the network, while also minimizing wasted address space. In contrast, the other options either provide too few usable addresses or are less efficient in terms of address space. For instance, a subnet mask of 255.255.255.128 only allows for 126 total addresses (2^7 - 2 = 124 usable), which would also work, but is less efficient when considering the need for just 40 devices, as it could lead to more unused addresses if additional devices were not added. A mask of 255.255.255.0 would provide 254

To determine the correct subnet mask for accommodating 40 devices, it is essential to consider how subnetting works in terms of available host addresses. Each subnet mask divides the IP address space into a certain number of subnets and hosts.

A subnet mask of 255.255.255.192 provides a block of 64 IP addresses (2^6 = 64), since the last octet allows for 6 bits to determine the hosts. Out of these 64 addresses, 2 are reserved: one for the network address and one for the broadcast address, leaving 62 usable addresses. This is more than sufficient, as it fits the requirement for 40 devices for the network, while also minimizing wasted address space.

In contrast, the other options either provide too few usable addresses or are less efficient in terms of address space. For instance, a subnet mask of 255.255.255.128 only allows for 126 total addresses (2^7 - 2 = 124 usable), which would also work, but is less efficient when considering the need for just 40 devices, as it could lead to more unused addresses if additional devices were not added. A mask of 255.255.255.0 would provide 254