PowerChute runs a script the pulls the host name/s from vifptarget library. If the DNS server is running as virtual machine (VM) and has been shut down or the DNS server is off line the ESXi host name/s cannot be resolved causing the shut down to fail.
NOTE: PowerChute Network Shutdown version 3.1 and 4.0 do not utilize vifptarget library. If running older versions of PowerChute Network Shutdown we recommend updated to the latest version.
Comparability information for PowerChute Network Shutdown can be found here.