Convert the IPv$4$ address whose hexadecimal representation is A$44$FF$1$BC to dotted decimal notation. $(10$p$)$

A network on the Internet has a subnet mask of $255\mathrm{.}255\mathrm{.}240\mathrm{.}0.$ What is the maximum number of hosts it can handle? $(5$p$)$

A large number of consecutive IP address are available starting at $198\mathrm{.}16\mathrm{.}0\mathrm{.}0.$ Suppose that four organizations, $A,B,C,$ and $D,$ request $4000,2000,4000,$ and $8000$ addresses, respectively, and in that order. For each of these, give the first IP address assigned, the last IP address assigned, and the mask in the w$.$x$.$y$.$z$/$s notation. $(10$p$)$

Why does UDP exist? Would it not have been enough to just let user processes send raw IP packets? $(5$p$)$

The first piece of code contains a server program that provides a service to a certain application, what is it$?$ Describe the code by adding comments to each line? $(10$p$)$

The second piece of code contains a protocol that allows unidirectional data flow over an unreliable channel, which Protocol is that? Describe the code by adding comments to each line? $(15$p$)$