Since the OAB regenerates every morning, there will be 400 megabytes of extra network traffic each morning as 200 users download the extra 2mb worth of photos in the OAB.
At Catapult, our OAB only increased by a factor of 3k per user, the file increased from 367kbytes to 973kbytes (see screenshots below).
For example, the size of each thumbnail in Active Directory is limited to 10k.
So in a company with 200 users, the OAB size could increase by as much as 2 megabytes (10k x 200).
Also the Update button seems to have to do something with "Outlook Social Connector" - see the other screenshot I added?
Outlook Social Connector is normal - I have it on my contacts as well.
This will update contact information, pictures, phone numbers, etc. Now you have the most up-to-date information from Active Directory in your local address book. Under Send/Receive Groups, you should see an option to "Download Address Book." Now you will be prompted for a few options, and you can choose to update from the Global Address List (this is how your AD should push out contacts). I download the full address book and it loads for a couple of seconds. I open some contact which I haven't updated yet, click on update - it is updated.By default, the OAB includes just a pointer to the photo rather than the photo itself.However, if you modify the OAB, then should be prepared for the increased network traffic that will result.These screenshots are from Outlook 2013, but the process works identically in 2010 or 2007. Choose "Update All", wait a moment, and you're done. I can manually update each contact with the nice "Update" button and it automatically synchs the contact with AD, but I can't do that for all contact with a simple buttonclick? Switch to your contacts view, then go to the "Send/Receive" tab. From there, right-click any selected contact and choose "Add to Contacts".