if it is CentOS 6.2 it is unsupported
if it is Scientific linux 6.2 there are only security fixes
if this is RHEL 6.2
your signature says you passed the RHCE
So you already KNOW
how to set up a rhel system -- you state that you passed those tests .
from this statement
I have copied the DVD contents under /var/ftp/pub
It looks like you are trying to use RHEL 6.2 without the required support contract .
So installing the current "deltarpm" is basically going to be near impossible ( well rather hard to do ).