I think sysadmin1138 and Gilles have this question pretty much nailed down... So I'm just going to address this:
Which site should I post to?
There's an old blog post on this...
Is it really so hard to figure out which community you belong to, and thus, where your question belongs? Ask yourself this:
- what is your job title?
- which community do you consider yourself a part of?
- what are you trying to accomplish?
Open up the FAQ on any of these sites. The first sentence, in the first section, should look pretty similar to this:
Server Fault is for system administrators and desktop support professionals, people who manage or maintain computers in a professional capacity.
Then there's the bit about the various sorts of questions that are appropriate. But, that's secondary. You can't enumerate in a reasonable space every topic that system administrators - or webmasters, or programmers - might need to ask questions about in the course of doing their jobs. The important thing to realize is that you're here because you have a question for the other folks who frequent this site - and that line describes them.
This notion that there's one and only one perfect site for every question is nuts. There were plenty of sites where you could ask questions like these before the site launched, and there are plenty of questions that still aren't appropriate anywhere on the Stack Exchange network. If today there are three sites where you could conceivably ask a given question and tomorrow there are 50, that doesn't matter so long as it can still be asked here, answered by these experts, and benefit those who've come to know this site as the place to look for answers.
So the answer to the question of "where to ask", if you're a sys-admin looking for answers from other sys-admins, is usually going to be: Right here!