we installed the kdump on redhat machineso under /boot we have initrd-2.6.32-642.el6.x86_64kdump.imgbut from /etc/grub.conf initrd-2.6.32-642.el6.x86_64kdump.img file not defined I just want to know how kdump initrd works inspite kdump initrd not defined in grub.conf 
linux + kdump concept and kdump initrd file
linux;rhel;grub;initrd