  For a graph $G$, the central graph $C(G)$ is the graph constructed from $G$
by subdividing each edge of $G$ with one vertex and also by adding an edge to
every pair of non-adjacent vertices in $G$. Also for a graph $G$, let
$\gamma(G)$ and $\tau(G)$ be the domination number of $G$ and the minimum
cardinarity of a vertex cover of $G$, respectively. In this paper, we give a
new classification of graphs concerning the domination number of central graphs
and minimum vertex covers of graphs. Namely, we show that any graph $G$ with at
least three vertices can be classified into one of the two classes of graphs
with $\gamma(C(G))=\tau(G)$ and $\gamma(C(G))=\tau(G)+1$, respectively,
together with some special properties concerning a vertex cover of $G$. We also
give some new results on the domination number of central graphs.
