So I'm a linux noob, been using Fedora(on my desktop) and CentOS(on my servers) for a few years now. I just had an interview for a company I really like. I'm mostly going to be doing the VMware / EMC stuff, but they run Postfix, amongst other things, on Ubuntu server. Now I've always been of the mind that I would learn one thing really well in IT before I would move on to other products. I don't feel like two years of RH/COS would put me in a position to know it well. I'd like to get my RHSA/E, but is this Ubuntu thing going to screw me up?

Generally speaking Linux builds on UNIX concepts, Open Standards, et cetera. On the distro level Ubuntu is based off of Debian and like Red Hat it comes with extensive documentation. On a lower level daemons like any MTA still require configuration files, iptables still powers Netfilter, ifconfig still configures interfaces etc, etc. So apart from issues like init vs systemd, su vs sudo, SELinux vs AppArmor I'd say that from a distro-agnostic point of view core functionality doesn't change (much). As long as your knowledge of system and networking concepts is OK I'd say just take notes, make backups, use a virtualization client to test stuff, read a lot and have fun.

I don't think it would screw you up too bad because Linux still requires a certain finesse at troubleshooting. However, you will not get used to using tools available in RedHat a certain way. For instance, SELinux with sebool setting and policy modules would be one draw back. SELinux isn't on Ubuntu out of the box last time I checked (I could be wrong as I don't use Ubuntu Server).

The yum and rpm utilities on RH is another difference (which you may already know) vs. apt and dpkg on Ubuntu but that's just a matter of man pages so not too bad.

I would say, while it is useful to keep your troubleshooting mind sharp I do not believe just using Ubuntu will allow you to pass the RH exams without extra studies outside the Ubuntu arena.

SAM

Ya, I'm still going to use Fedora at home and maybe even for my work computer if they let me. I figure the RHSA/E is going to take a lot of studying on my part anyway. But things like say Postfix, Apache, MySQL, or Bash scripting would be virtually the same right? I'm actually really excited about this regardless. Thanks for the replies.

Becoming more "well-rounded" is both satisfying and (potentially) beneficial in future as well.
May seem daunting at present, but you'll get the hang of both reasonably easily I suspect. Go for it.

Yes bash, apache, postfix, and the like are the same no matter where you use it.

I'm not sure the number of servers you manage but you should start using cluster ssh, vim, and screen. They're invaluable to large installation system administration.

No I don't think it'll screw you up. It actually makes you more valuable.

I worked in a shop that used mainly Solaris...and I got my RHCE at that time.

Knowing multiple OSes makes your more marketable.

-C

Or you could just stay where you are professionally?