  We show using the entropy function formalism developed by Sen
\cite{Sen:2005wa} that the boundary term which arises from the Einstein-Hilbert
action is sufficient to yield the Bekenstein-Hawking entropy of a static
extremal black hole which is asymptotically flat. However, for asymptotically
$AdS$ black holes, the bulk term also plays an important role due to the
presence of the cosmological constant. Further, we show that for extremal
rotating black holes, both the boundary and the bulk terms contribute
non-vanishing pieces to the entropy.
