Briefly mention the functions of the following first four layers of the OSI layers:

$4\mathrm{.}1\mathrm{.}1$ Network Layer. $(1)$

$4\mathrm{.}1\mathrm{.}2$ Data Link Layer:

$($i$)$ Logical Link Control $($LLC$)$ and $(1/2)$

$($ii$)$ Media Access Control $($MAC$).(1/2)$

$4\mathrm{.}1\mathrm{.}3$ Physical Layer. $(1)$

$4\mathrm{.}1\mathrm{.}4$ Physical Medium.