I started a helpdesk job for a linux webhost recently, and things are going very well, but I still feel like I'm in way over my head right now. I have 8 years of linux experience, but that's mostly workstation level, very little of that is with any kind of webhosting server setups.

The main functions of my job are supporting centos servers, which use utilities common to website hosting such as apache, php, mysql, exim, an iptables wrapper (csf, very nice firewall, I use it on my personal systems as well), all mostly over ssh and a web-interface control panel. As a result, I need a very firm understanding of dns/rdns standards and such related things like a/mx/spf records, nameservers, registrars, mail protocols and related troubleshooting of all the above and any other problems that could possibly arise with a web server. It's a little overwhelming how much there is, but I'm eager to learn it all, and know I can quickly pick it all up. With the right direction in study of course.

This brings me to my question: what is the most useful/important things/areas I will need to learn/study for this position, and where can I find good reliable resources for these areas? I've googled as problems come up, I google things I don't know when I'm at home, but it all seems to be a very inefficient way to learn what is required for this job. Where should my focus be, rather than bouncing between trying to learn a lot of what I think may be useful?

They are providing on-job training, but I'd like to suppliment this to learn faster than I can 1 ticket at a time. I want to know everything possibly related to linux webhosting, and related security, as quickly as possible. Could you all point me in some good directions for some more focused studying please? Any advice, suggestions, and/or offer of general help is greatly appreciated. Thank you!

1. get yourself a webhost where you work - "eat your own dogfood"
As well as being able to see things from the client's point of view it gives you a safe place to test/break/fix stuff
(really they should supply this for work or give you a free/discount one; ask for one and explain why... you never know..)

2. Lots of free to read manuals (real ones) here www.linuxtopia.org & remember that RHEL = Centos (apart from eg RHN subscriptions)

3. I don't know what you have at home, but I'd definitely have at least one Centos install if that's what work has.

4. for a more structured learning approach, take the courses/manuals at work as a good starting point, then expand your knowledge in each area.
Even though at work you're going to be covering all different areas, try to spend some of your own time on one topic at a time eg 1 or 2 weeks solid one one topic.
You need to do this to get it clear in your head.

Good luck

PS: you can fake a similar env at home by using VMs eg in Centos/RHEL, the kvm tech comes as std.

I learned a huge amount about web/db/other servers by building an ispconfig3 server. Ispconfig is a php based web hosting panel used by website resellers. For self-learning, following their complete "perfect server" tutorial and taking the time to understand why they put the server components together the way they did is very instructive.

All you need is an old cpu without an OS that will run Centos. Follow the tutorial step-by-step and you'll end up with a server suitable for use on the public internet. Visit https://www.howtoforge.com/tutorial/...nd-ispconfig3/ for the Centos tutorial. It's a good education, even if you don't need a server, although I use an ispconfig server on my internal network for development/testing and find it quite useful.