What is a valid IP address for a server connected to the DMZ network, given the default gateway is 192.168.55.1?

A valid IP address for a server connected to the DMZ network must be within the same subnet as the default gateway and should not conflict with any reserved or special addresses.

The default gateway is 192.168.55.1, which indicates that devices on the same subnet must fall within the range defined by the subnet mask. The subnet mask 255.255.255.0 allows for a range of IP addresses from 192.168.55.0 to 192.168.55.255. However, with the subnet mask 255.255.255.128, the subnet is divided into two networks: 192.168.55.0/25 (available addresses 192.168.55.1 to 192.168.55.126) and 192.168.55.128/25 (available addresses 192.168.55.129 to 192.168.55.254).

The address 192.168.55.5 with a netmask of 255.255.255.128 is valid because it falls within the first subnet, and it does not conflict with the gateway. This makes it a suitable choice for a server in the DMZ network. The other options