I'm sure the problem sparking this post has already been resolved however I figured I would post for others that may also have this problem. I came across this post as it was the only hit on Google that contained 'syncad2k3.ntttest.microsoft.com'.
@Marvin Oco ... I also experienced this when attempting to migrate a configuration; however, the configuration was 2016 functional level. Your post actually made me dig into my configuration and export in more detail. Thank you. When attempting to migrate an exported configuration to a new AD Connect server I saw the mentioned 2k3 directory. From my experience the the exported configuration on the source contained an unconfigured/potentially corrupt connector. After the identified misconfigured connector was removed from the configuration on the original source connector server, I performed a new configuration export and went through the import process on the new server. The mentioned directory was no longer displayed and I was able to proceed with the correct domain connectors. In my scenario I was migrating 5 different connectors associated with separate domains.
