I had this question after viewing Commannds needed to force the update of the Global address list in exch 2013
After creating new Distribution Groups, through CAS webgui we see the change.
Outlooks however dont update, if we delete oab files we do see the change, but once we download offline we dont see the change anymore.
Get-GlobalAddressList | Update-GlobalAddressList
Get-OfflineAddressBook | Update-OfflineAddressBook
and also restarted Mailbox Assistant Services, still no luck.
They dont show up under Global Address list, but shows up properly under All Distribution Lists after its downloaded offline.