4.3 Propagation of Push Notification with Persistent Association
The following figure shows the sequence of messages involved in propagating a push notification. NBNS server 1 is a push partner of NBNS server 2, which is also a push partner of NBNS server 3. It is assumed that persistent associations are used and have existed between the servers before the operation starts.
Suppose that the administrator on NBNS server 1 starts a push notification to NBNS server 2 with propagation. Upon the administrator's request, NBNS server 1 sends an Update Notification message to NBNS server 2.
Upon receiving the message, NBNS server 2 sends a Name Records Request message to NBNS server 1, and gets the updated name records from NBNS server 1 in the Name Records Response message.
After NBNS server 2 has processed the name records, it sends an Update Notification message to NBNS server 3, which will again do the same as NBNS server 2 has done to replicate the name records.

Figure 10: Example of propagation of push notification with persistent association