Q: I saw an update for my Windows Server virtual machines on Windows Update related to Integration Services; what has changed?
A: Previously, to upgrade the Integration Services for Windows virtual machines running on Hyper-V, an ISO was inserted into the virtual machine via the Insert Integration Services Setup Disk action, which contained the latest Integration Services versions. The ISO, vmguest.iso, is updated on the host as it receives updates and is automatically rebuilt. This model starts to fall apart when you look at the direction of Windows Server vNext that enables mixed clusters; for example, hosts running Windows Server 2012 R2 and Windows Server vNext together. The new approach for Windows is that the Integration Services updates will be delivered by Windows Update. This is more in line with Linux, in which the integration services are built into the OS and updated via the normal support channel. Microsoft has an article on this new behavior in the TechNet article "Hyper-V integration components are available through Windows Update."