Checking kernel version
root@linux:~ # uname -r
2.6.18-407.el5
When you try to install an older kernel, you will receive a message that you already have a newer version of the package already installed
root@linux:~ # rpm -ivh kernel-2.6.18-348.el5.x86_64.rpm
Preparing… ########################################### [100%]
package kernel-2.6.18-407.el5.x86_64 (which is newer than kernel-2.6.18-348.el5.x86_64) is already installed
Run with –oldpackage to install the old kernel
root@linux:~ # rpm -ivh –oldpackage kernel-2.6.18-348.el5.x86_64.rpm