When creating a Virtual Distributed Switch (vDS), if the "Create a default port group" checkbox remains checked, a default portgroup labeled as "DPortGroup" (or "DPortGroup #" if a portgroup labeled "DPortGroup" already exists) is created with the vDS.
vCenter (all versions)
This is expected behavior if the "Create a default port group" checkbox remains checked during vDS creation.
During vDS creation, unchecking the "Create a default port group" box will prevent a default portgroup to be created.
Alternatively, if the default portgroup has been created already it can be managed similarly to any other distributed portgroup, i.e. renamed, modified or removed completely from the vDS if unused.