If the system uses the ext3 file system or a SCSI controller, an initial RAM disk is needed. The purpose of the initial RAM disk is to allow a modular kernel to have access to modules that it might need to boot from before the kernel has access to the device where the modules normally reside.
The initial RAM disk can be created with the mkinitrd command. However, this step is performed automatically if the kernel and its associated packages are installed or upgraded from the RPM packages distributed by Red Hat, Inc.; thus, it does not need to be executed manually. To verify that it was created, use the command ls -l /boot to make sure the initrd-2.4.20-2.47.1.img file was created (the version should match the version of the kernel just installed).
The next step is to verify that the boot loader has been configured to boot the new kernel. Refer to Section 30.6 Verifying the Boot Loader for details.