The following errors can occur on a server that is forwarding information to another Notification Server.
Date: Jun 02 22:24:37:000
Description: Failed to discover domain details for 'MachineName' Error: 53
Date: Jun 02 22:24:37:001
Description: Unable to detect duplicate item for resource MachineName. Reason: Failed to discover domain details for 'MachineName' Error: 53
Assume that resource is non duplicated and continue processing.
Before Inventory Forwarding sends up data it checks to see if the resources are retired, and if it is then it saves it as an unmanaged resource so that the information does not get forwarded. During this save process the NS checks to see if it is a duplicate (because it is essentially saving itself over another record) and this is when the discovery code gets called.
The process is failing because for whatever reason the Notification Server cannot contact that machine (it may be off or there may be network polices etc in place to prevent it from contacting it) and this warning gets thrown.
This is working as designed.
Notification Server SP3