255.255.255.255) does not have room for any bits for the subnet portion of the IP address, so it can be considered a special or even degenerate subnet consisting of only 1 IP address, namely the IP address like
184.108.40.206, and no network address, no broadcast address. But it can be useful to refer to a solitary IP address.
In normal subnets (but see an exception below), there would be a network address (subnet portion of the IP address consisting of all zeros) and a broadcast address (subnet portion of the IP address consisting of all ones). So if there are n bits in the subnet portion of the IP address, then there are 2^n-2 possible regular IP addresses that can be allocated in this subnet (minus 2 for the network and broadcast addresses).
So /30 (255.255.255.252) is the smallest subnet in this sense, that it has 2 regular IP addresses that can be used besides the network and broadcast addresses (but see the description of /31 below).
In your example, if it is /30, we would have:
- network address:
220.127.116.11 (00 in last two bits)
- broadcast address:
18.104.22.168 (11 in last two bits)
- 2 regular IP addresses
There's also /31
You may wonder, for small subnets, do we really need to waste two IP addresses for broadcast and network? Especially for point-to-point subnets with just one interface on each end, RFC 3021 allows /31 (255.255.255.254) that consists of only two IP addresses, no network address and no broadcast address.
In your example, if it is /31, we would have:
- 1st regular IP address:
22.214.171.124 (0 in last bit)
- 2nd regular IP address:
126.96.36.199 (1 in last bit)
Would there be any problems with routers interpreting these as network address or broadcast address? Not if they follow RFC3021 (which most routers do), and make exceptions for /31 networks.
Hence, it is popular for a point-to-point link which can use an IP address at each end. It saves 2 IP addresses for each time /31 is used rather than /30.