There are several ways to determine if there is an updated kernel available for the system.
Go to http://www.redhat.com/apps/support/errata/, choose the appropriate version of Red Hat Linux, and view the errata for it. Kernel errata are usually under the Security Advisories section. From the list of errata, click on the kernel errata to view the detailed errata report for it. In the errata report, there is a list of required RPM packages and a link to download from the Red Hat FTP site. They can also be downloaded them from a Red Hat FTP mirror site. A list of mirror sites is available at http://www.redhat.com/download/mirror.html.
Use Red Hat Network to download the kernel RPM packages and install the packages. Red Hat Network can download the latest kernel, upgrade the kernel on the system, create an initial RAM disk image if needed, and configure the boot loader to boot the new kernel. For more information, refer to the Red Hat Network User Reference Guide available at http://www.redhat.com/docs/manuals/RHNetwork/.
If the RPM packages were downloaded from the Red Hat Linux errata page or Red Hat Network was only used to download the packages, proceed to Section 30.4 Performing the Upgrade. If Red Hat Network was used to download and install the updated kernel, following the instructions in Section 30.5 Verifying the Initial RAM Disk Image and Section 30.6 Verifying the Boot Loader, except do not change the kernel to boot by default because Red Hat Network automatically changes the default kernel to the latest version.