You need to know all active Task Servers.
ITMS 8.x, 8.7.x
By default, there is a report that you could use under Reports > All Reports > Task Server > Status:
Task Server Summary
As well, you could use the following steps to create a custom Report:
-- All Active Task Servers.
select aaca._ResourceGuid, vcx.Name, vcx.[IP Address], aaca.[Agent Name],
aaca.[Product Version], aaca.[Build Number], aaca.[Install Path]
from Inv_AeX_AC_Client_Agent aaca (nolock)
inner join vComputerEx vcx on vcx.Guid = aaca._ResourceGuid
where aaca.[Agent Name] = 'Altiris Client Task Server Agent'
and aaca._ResourceGuid in (
select ats.ResourceGuid ActiveGUID from vActiveTaskServiceComputers ats
)