A network administrator is adding a new LAN to a branch office. The new LAN must support 4 connected devices. What is the smallest network mask that the network administrator can use for the new network?

To support 4 connected devices, you need a subnet that can provide at least 4 usable IP addresses for hosts. Remember that in any given subnet, two IP addresses are always used up – one for the network address and one for the broadcast address, so you need a subnet that provides at least 6 addresses in total.

Here’s how the subnet masks break down in terms of number of available hosts:

• 255.255.255.192 – This is a /26 subnet mask, which allows for 64 addresses in total, but with 2 addresses used for network and broadcast, you get 62 usable addresses.
• 255.255.255.224 – This is a /27 subnet mask, which allows for 32 addresses in total, with 30 usable addresses.
• 255.255.255.240 – This is a /28 subnet mask, which allows for 16 addresses in total, with 14 usable addresses.
• 255.255.255.248 – This is a /29 subnet mask, which allows for 8 addresses in total, with 6 usable addresses.

The smallest subnet mask that will support 4 connected devices (requiring 6 addresses in total) is 255.255.255.248 or a /29 subnet mask.