Pre-requisites: Active Directory are configured under Sync Settings.
Step 1 - Navigate to Directory Settings
Navigate to Settings > Directory Settings as shown below.
Step 2 - Select Active Sync Mobile Settings
Click the Active Sync Mobile Settings tab as shown below.
Step 3 - Specify Exchange server details
Specify the Account Suffix, Base DN and Domain Controller details specific to your Exchange server.
Step 4 - Save the details
Click on the Save button to save the details.