Image exchange chat
The attribute values returned from the query are also stored in the cached Address Book Service entry for the user.The Address Book Service deletes all cached images every 24 hours, which means that it can take up to 24 hours for new user images to be updated in the cache on the server.The configured policy settings are sent to clients through in-band provisioning.
When you choose the Default corporate picture option, Lync gets the photo displayed for you from Active Directory Domain Services.
If the values are different, the client retrieves the image file of the signed-in user with an HTTP GET request.
Additionally, the client checks with the server every 24 hours from the time at which the cached version of the image file was created to compare the value of the Photo Hash attribute on the server with the value on the client.
The image used is the image defined as the value for the thumbnail Photo attribute in Active Directory Domain Services.
This is the same file that is used by Exchange to display images in Outlook.
You can also choose whether or not to display photos for your contacts in Lync client.