$18.$ Answer the following questions on IP addresses

$($i$)$ What is the prefix length notation for the subnet mask $255\mathrm{.}255\mathrm{.}255\mathrm{.}224?$

$($ii$)$ State the IPv$6$ address that is not routable and is used only for communication on a single subnet?

$($iii$)$ An organization is assigned an IPv$6$ global prefix of $2001$:db$8$:$1234$::$/48.$ What is the maximum number of $/64$ subnets the organization can create with this space?

$($iv$)$ Given the subnet $192\mathrm{.}168\mathrm{.}1\mathrm{.}0/26,$ what are the first and last valid host addresses of the first subnet?

$($v$)$ A PC has been assigned the IP address $192\mathrm{.}168\mathrm{.}0\mathrm{.}168/29.$ How many more useable host addresses are left to be assigned on this network?