\documentclass[varwidth=true, border=2pt]{standalone}
\usepackage{tikz}
\usetikzlibrary{arrows,positioning}

\begin{document}
  \tikzstyle{vertexs}=[draw,fill=black,circle,minimum size=4pt,inner sep=0pt]

  \begin{tikzpicture}
    \foreach \x in {0,1}
    \foreach \y in {0,1}{
      \node (Node-0-\y)[vertexs] at (\y,0) {};
      \node (Node-\x-1)[vertexs] at (\x,1) {};
    }
    \draw (Node-0-1) -- (Node-1-1);
  \end{tikzpicture}
\end{document}