Your network contains a server named Server1 that has System Center 2012 Virtual Machine
Manager (VMM) installed. You plan to deploy a service named Service 1. Service1 will contain three
tiers. Each tier will contain 10 instances. You need to configure the service template to ensure that
when an application in Service1 is upgraded, Service1 remains available. What should you configure
for each tier?
A.
the maximum instance count
B.
the preferred servicing order
C.
the preferred deployment order
D.
the number of upgrade domains
E.
the minimum instance count
Answer should be D
More info: https://blogs.technet.microsoft.com/scvmm/2011/05/18/scvmm-2012-an-explanation-of-scale-in-and-scale-out-for-a-service/
The Upgrade Domain value for this virtual machine instance based on the Number of upgrade domains for the tier as well as the existing number of instances on the tier. Upgrade domains provide a partitioning of the virtual machines on a tier when servicing the service. All virtual machines in the same upgrade domain are serviced together. This allows virtual machines in other upgrade domains to remain connected to the service (allows the service to be up) during the servicing.