$($a$)$ Give the subnet mask for dividing Network $10\mathrm{.}0\mathrm{.}0\mathrm{.}0$ into $14$ equal$-$size subnets.

$(5$ marks$)$

$($b$)$ In the information technology area, briefly describe what the function of network address

translation $($NAT$)$ technology is$.$

$(3$ marks$)$

$($c$)$ In the information technology area, briefly describe what virus and worm are.

$(5$ marks$)$

$($d$)$ Denial of service $($DoS$)$ means that a service is being denied to a computer, a network, or a

network server. Briefly list three examples of DoS attack.

$(3$ marks$)$

$($e$)$ Briefly describe the four steps $($i$.$e$.,$ four different messages$)$ for a computer to obtain an IP

address from the dynamic host configuration protocol $($DHCP$)$ server.

$(4$ marks$)$