I run an update to about 150 different subnets with a server as the mdr at each subnet every month, and for some reason about 4 of them claim they can't detect a MDR even though it's there and online. Landesk can even push jobs to the MDR, but all the clients on the subnet fail any attempt to multicast to them. Any ideas what is causing this issue? Is there some way to force clients to recognize the MDR?
If you've designated a static MDR for each subnet then you may want to check your firewall settings to make sure those clients can communicate via multicast. The ports we use are UDP 33355 and 33354 for multicast software distribution. Also validate that those clients who are failing are at the same patch level as the core.