Category	Cause of failover
Unable to access server	The server is down
	There are network connectivity problems
	The server has reached the maximum number of users allowed (set with Server_MaxUsers in NOTES.INI)
	The server is restricted by the administrator (using the Server_Restricted setting in NOTES.INI)
	The server is BUSY because it has reached the maximum load allowed (the server availability threshold)
Unable to access database	The database is marked "Out of Service" in the Cluster Database Directory
	The database is marked "Pending Delete" in the Cluster Database Directory

Category	Action that triggers failover
Database open operations	Opening a database from a bookmark
	Clicking a document link, a view link, or a database link
	Using Domain Search when a clustered indexing server is unavailable
	Accessing roaming files when a clustered roaming server is unavailable
	Activating a field, action, or button that contains @command ([FileOpenDatabase])
	Running a LotusScript® routine that contains the OpenWithFailover method of the NotesDatabase class
	Using Java(TM) that contains the OpenDatabase method of the DbDirectory class
	Replicating with a database on a cluster server that is not running or not reachable on the network
Mail server related operations	Sending mail
	Name lookups
	Type-ahead
	Routing mail messages
	Mail predelivery agents
	Meeting invitations
	Free time lookups
	Server lookups
Web server operations	Selecting the Open URL icon
	Clicking a URL hotspot
	Accessing a URL with a Web browser

Failover does not occur in the following cases:

• When a server becomes unavailable while a user has a database open

  Note The user can reopen the database, which causes failover to a different replica, if one exists in the cluster. If the user was editing a document when the server became unavailable, the user can copy the document to the replica.

• When a user chooses File - Database - Properties or File - Database - Open
• When the router attempts to deliver mail when you've disabled mail routing failover or set MailClusterFailover to 0
• When the template server is unavailable while creating a new database
• When a server fails while running agents, other than the mail predelivery agents
• When a server fails while running the Administration Process
• When replicating with a server that is restricted by the administrator or has reached the maximum number of users or the maximum usage level set by the administrator. Also, when replicating with a database marked "Out of Service." Replication occurs regardless of such restrictions, so there is no need for failover to occur.

How failover works
How Domino finds a replica during failover