[ale] Centos admin online training?

[neal at mnopltd.com]

So, if you had a client who needed to train someone who is doing 
operational stuff on Centos to be a halfway decent administrator, NOT 
building systems from scratch, but day to day stuff, NOT VMs, and of 
course you can't send them away for a month to boot-camp, what online 
training resources would you point them towards?

regards,
Neal (trying to stay retired)