There were reports of Server Admin complaining of invalid serial numbers after upgrading to Mac OS X 10.5.8 Server, most of which were from servers with multiple different physical ethernet ports with IP addresses on the same subnet. A few people were reporting that this was happening to them with ports on different subnets and even when using Link Aggregation, but it sounded like heeding Apple’s note that multiple physical network interfaces on the same subnet may cause routing issues solved the issue for most.

Well, Apple has since released Mac OS X Leopard Server 10.5.8 v1.1 and Network Registration Update 1.0 (for Mac OS X Snow Leopard Server 10.6) which resolve the issue, so there was definitely a bug there. I’ll put together a separate post regarding multiple physical network interfaces on the same subnet.

[Via AFP548]