To configure high availability for the BlackBerry® Administration Service and enhance its performance, you can configure a pool of two or more BlackBerry Administration Service instances.

The BlackBerry Administration Service verifies that sessions between BlackBerry Administration Service clients and a BlackBerry Administration Service instance remain persistent. The clients that communicate with the BlackBerry Administration Service are the BlackBerry MDS Integration Service, BlackBerry® Enterprise Server Resource Kit, BlackBerry Monitoring Service, browsers, and third-party applications that uses the BlackBerry Administration Service APIs. If a BlackBerry Administration Service instance stops responding or shuts down, all clients must log in again. Sessions are not reassigned automatically.

To permit browsers to distribute requests across the BlackBerry Administration Service instances and to avoid a single point of failure, you can select one of the following high availability options:

• DNS round robin
• hardware load balancer

If you configure DNS round robin, the DNS server stores the IP addresses of all of the BlackBerry Administration Service instances and the pool DNS name. All clients must resolve the DNS name into the list of IP addresses and try to connect to each BlackBerry Administration Service instance until a connection opens. If the client is a third-party Java® application, you must turn off DNS caching at the JVM level. Third-party Java applications must maintain a list of available and unavailable BlackBerry Administration Service instances.

• How the BlackBerry Administration Service pool manages job tasks, notification tasks, and reconciliation tasks
  
• BlackBerry Administration Service high availability using DNS round robin
  
• Best practice: Planning for BlackBerry Administration Service high availability
  
• Scenario: What happens after the BlackBerry Administration Service stops responding