User profile sync issue with AD

Some times SharePoint doesn't allow to sync the user profile properties from AD to SharePoint. After starting the incremental and full sync, SharePoint 2010 user profile doesn't sync the properties with AD. i.e the updated data in AD is not being updated in SharePoint 2010. We can provide Replicate Directory Changes permission to user profile sync service account. The Replicate Directory Changes permission allows an account to query for the changes in the directory. This permission does not allow an account to make any changes in the directory. The Grant Replicate Directory Changes permission does not enable an account to create, modify or delete AD DS object. The same is mentioned at http://technet.microsoft.com/en-us/library/hh296982.aspx