Using Azure AD Connect command-line to synchronize objects between on-premises and Microsoft Azure, the administrator has two switches initial and delta and we will use both of them and check what it does in the background.
Just to make sure that we are on the same page, the command-line utility to synchronize Active Directory on-premises with Microsoft Azure is DirectorySyncClientcmd.exe which comes with Azure AD Connect utility. If you are using an older version of the tool, you may want to consider upgrading to the new one after proper testing and validation.
The tool can be found at C:\Program Files\Microsoft Azure AD Sync\bin folder and the tool is a simple .exe file. The tool has two main switches : initial and delta as shown in the figure below, and they can be followed by staging which we are going to check towards the end of this Tutorial.
In order to understand what the tool is doing although all the information is provided on the output we will use Synchronization Service Manager to track all operations.
The first test is running DirectorySyncClientCmd.exe without any switches, and that is the same as delta, and the process will be a delta import, delta synchronization and export (twice because it is one for each Directory: on-premises and Microsoft Azure).
Just to make sure that running without switches and using delta switch is the same thing, we cleared the logs on the Synchronization Service Manager and we ran again the command-line using delta, and the result was the same. So it is safe to say that for regular synchronization no additional switches are required.
The final switch is initial and the difference between that one and the previous switches is that a Full import and synchronization occur, as shown on the logs below.
You may be wondering, what happens when the staging switch is used with either delta or initial. Well, since we are here it is better to get testing, but the difference is that the export tasks will not occur.