We have three regions in our Exchange 2007 environment - EMEA, APAC, and AMERCAS (AMER). Our OAB server, the one where it's actually generated, is NY-EXCH1. Each region then has three CAS servers for OAB distribution to clients - AMER-CAS1, AMER-CAS2, AMER-CAS3 in the case of the States. Let's say I have a client in NY that doesn't seem to be downloading the latest OAB. How is it possible to find out which CAS server the client is attempting to download the OAB from? From what I can see, the \OAB\<GUID> folder on all the AMER CAS servers is up to date, it's just that the clients don't seem to be download the latest one looking at the OAB file dates on the client.

Hi, As we know , Mailbox responsible for generate OAB. On a default installation, the OAB files are stored in C:\Program Files\Microsoft\Exchange Server\Exchange OAB CAS server runs a service named Microsoft Exchange File Distribution Service which copies the OAB files from the mailbox server. The default location is : C:\Program Files\Microsoft\Exchange Server\Client Access\OAB. By default, OAB is updated only once in 24 hours at 5am. You can customize the update schedule depending upon your requirements. Under this folder , you could see the last modified time. For Outlook client, you could press “CTRL” and click outlook icon, click “connection status”, then you will find where Outlook download OAB from. More information about OAB http://technet.microsoft.com/en-us/library/bb232155(EXCHG.80).aspxPlease remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.