The dependence of the partial polarizability on $n$ is explained as reflecting structural difference of the two kinds of counterions. $\alpha_{\mathrm{L}}(n)$ increases until the DNA phosphate charge is neutralized by about 60 counterions. Note that it is calculated at every simulation step by selecting the innermost counterions. Then fluctuation of the $z-$component of the dipole moment $\mu_{z}(n)$ will increase with $n$ when $n$ is small because selected counterions may distribute randomly along the polyion rod axis. When the number of the selected counterions increases over 60, fluctuation of $\mu_{z}(n)$ levels off somewhat until $n$ reaches about 80 because, since most of the condensed counterions firmly bound in the immediate vicinity of the polyion are selected, they distribute uniformly along the DNA. When $n$ exceeds about 80, first the outer part of the condensed counterions which are less firmly bound to the polyion and then the Debye-H\"uckel ion atmosphere begin to contribute to $\mu_{z}(n)$ with their diffuse spatial distribution reflected in the rapidly increasing fluctuation of $\mu_{z}(n)$. Fluctuation of $\mu_{x}(n)$ and $\mu_{y}(n)$ remains very small when $n \le 80$ because ions are condensed in a layerover the DNA surface. When $n>80$, first the outer part of the condensed counterions and then the Debye-H\"uckel ion atmosphere starts to contribute to both $\mu_{x}(n)$ and $\mu_{y}(n)$ resulting in their rapidly growing fluctuation. .