This blog post is written Dell Hypervisor Engineering team
The DellEMC PowerEdge 14G servers’ factory installed with VMware ESXi (from June 2017 till June 2018) will have root password set to Server Service Tag. Refer to <Locating Service Tag of your system> section under Getting started guide at dell.com/poweredgemanuals on locating service tag.
From June 2018 onwards, the DellEMC PowerEdge 14G servers’ factory installed with VMware ESXi will have root password set to Server Service Tag followed by Exclamation mark. Refer to "Custom DCUI screen for DellEMC customized VMware ESXi" which detail about the custom DCUI screen Dell EMC introduced to notify this change. The change in password is due to the password complexity policies revised for vSphere 6.7. Refer to vSphere Security document to know about the password complexities.