$($a$)$ State four computer network security threats.

$(4$ marks$)$

$($b$)$ Describe each of the following with respect to network security:

$($i$)$ confidentiality;

$($ii$)$ integrity;

$($iii$)$ authentication.

$(6$ marks$)$

$($e$)($i$)$ With the aid of a labelled diagram, describe MESH LAN topology;

$($ii$)$ State two merits of the topology in $c($i$).$

$(7$ marks$)$