On occasion, it may be required of you to force a sync between your local AD environment and your MS Azure / Office 365 environment. By default, this value is about 3 hours. For whatever reason, you need to make a change to a user object, you may need to perform this sync so they can utilize the services.
This command is very simple to execute.
- Open an elevated Windows Azure AD Module for Powershell window.
- Navigate to the “C:\Program Files\Microsoft Azure AD Sync\bin” folder.
- Run either the .\DirectorySyncSlientCmd.exe with either the Initial or Delta argument.
For a detailed explanation of the arguments, check out the source article links at the bottom.
Source : How to execute initial or delta sync via command-line