RHEL 5 - what is the use of installation key?
 

Please let me know what is the use of the installation key which the RHEL 5 installer asks us while installing the OS. Is it something related to Red Hat Network registration. What is the difference between this installation key and the Red Hat Network registration?
Thanks.

I would guess that it is a key to verify that you have a valid license. Did you buy RHEL? If so, there should be instructions.

If you did not buy it, but you really need RedHat, you might want to look at the free clone---CentOS.

the installation key is used to determine the available package selection (Virtualization, Clustering, Cluster Storage)... If you have RHEL5AP entitlements associated with the system on RHN post-install you may still install these from RHN and/or from the installation media. If you skip the key, the options to install the packages in those groups is not available during installation; if you have a key for them and use it, then you can select packages from those groups during install.

Thanks pixellany and rayfordj..
rayfordj, my doubt is, even if I skip the installation key during installation, I can install those packages later from the DVD via yum or rpm utilities, is it not?
so, is it something like this:

If you enter the installation key during installation, you have the option to install xen and packages related to clustering during installation itself; if you skip it, you only need to install them later from the DVD. Is this correct?

You'll need the key later to get the updates for the non-Base groups as mentioned.