The API Remoting Web Service is not working

So, ever since I upgraded from WSUS 2.x to 3.x, I have been seeing this error in my Application log. I couldn't find anything broken, I just kept seeing this error. After countless searches on Google and many hours wasted--I gave up. This morning I decided I really didn't like this error, so I decided to giver 'er another go.

• I checked all the File Permissions as directed by TechNet
• I checked all the Registry permissions as directed by TechNet
  
• I checked all the ISS permissions as directed by TechNet
• I restarted IIS, Reset IIS, & restarted the WSUS Service
• I ran wsusutil.exe checkhealth
  

Still nothing.

As I'm staring at the values in this registry key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Update Services\Server\Setup

I notice that the String "HostHeader" contained the external DNS FQDN instead of the Internal. I figure "that's odd", so I change it to the local DNS FQDN, host.domain.local. after all, I'm only running WSUS internally. Sure, I host our .com zone internally so things like OWA can be accessed from inside without having to give users yet another URL, but I figured that in this case, WSUS should be using the local FQDN no matter what.

SUCCESS!!

I went from basically seeing the Event ID 12012 about 4 or 5 times a day to not seeing it at all. Whowuddathunkit?

"The simplest things are ALWAYS DNS!"