The Notification Server is installed in a WorkGroup or Domain where computers in other Sites or Domains are only able to resolve the IP address of the Notification Server and not the Server Name. How can the Altiris Agent be pushed using the IP address of the Notification Server only?
You need to add some switches for the AexSWDInstSvc (Altiris Agent Installation Service) program.
(to look like this: -u http://10.103.65.109/Altiris/NS/NSCap/Bin/Win32/X86/NS Client Package/AeXNSC.exe -s 10.103.65.109 -w http://10.103.65.109/Altiris/).
For more details about AeXSWDInstSvc commands, see article 38380, "AeXSWDInstSvc (Altiris Agent Installation Service) Command Line Arguments."
See article 29334, "How to manage computers from different domains (without trust relationship between domains) from a single Notification Server" for more references about computers in multiple domains.