  In this paper, we investigate the domination number of generalized Petersen
graphs P(n, 2) when there is a faulty vertex. Denote by $\gamma(P(n,2))$ the
domination number of P(n,2) and $\gamma(P_f(n,2))$ the domination number of
P(n,2) with a faulty vertex $u_f$. We show that
$\gamma(P_f(n,2))=\gamma(P(n,2))-1$ when $n=5k+1$ or $5k+2$ and
$\gamma(P_f(n,2))=\gamma(P(n,2))$ for the other cases.
