[CentOS] Inquiry:yum?

> I tried for the other engaged rpm packages one-by-one . But at last , only
> the following one remained as unresolved :
> [root at mss-1 tmp]# rpm -Uvh yum-fastestmirror-1.1.16-13.el5.centos.noarch.rpm
> warning: yum-fastestmirror-1.1.16-13.el5.centos.noarch.rpm: Header V3 DSA
> signature: NOKEY, key ID e8562897
> error: Failed dependencies:
>        yum >= 3.0 is needed by
> yum-fastestmirror-1.1.16-13.el5.centos.noarch
> Can you please let me know why it does not come to an end ?

What is the output of "lsb_release -a"