I have two domain controllers in my domain. On the first dc I promoted, the Current: and Original: Update Sequence Numbers (USNs) are 4411. This dc holds all roles. The second dc has the Current: and Orginal: Update Sequence Numbers (USNs) of 8258. I found this by going to ADUC, went to the View tab and selected Advanced Features, selected System, then DomainUpdate, the right-clicked Windows2003Update and selected properties. My question is, should the USN numbers match on both controllers? Should both dc1 and dc2 either have 4411 or 8258? Or can these be different. I am asking this because I am trying to install exchange 2003 standard and I thought I read where these numbers should match. Other than that, I am not getting any event viewer errors in either Directory Service or File Replication Service and the system seems to be working well. No other problems or quirks have been reported. FYI, I am not installing exchange on a dc, I have another computer that I will install it on.