Installing a standard MediaWiki installation on a server:
Using MySQL on a different server:
I've created the user
wikiuser and the schema/db:
itwiki and assigned all the proper permissions, etc for the user to that schema.
During the MediaWiki installation I get the following error:
Attempting to connect to database server as wikiuser...failed with error  Can't connect to MySQL server on 'mysql.ourdomain.com' (13).
I have the correct hostname, user, password and schema entered though. In order to verify my user permissions, I reverted back to the shell on the same web server:
> mysql -u wikiuser -p -h mysql.ourdomain.com
And that allowed me to successfully connect to the database when I entered the password.
So something weird is going on here. I can connect just fine from the command line, but MW is not allowing me to connect. Any thoughts on where I should be looking to troubleshoot this behavior?