This is regarding the Dependencies.

[pmpstudent]

I am unable to differentiate between Mandatory dependency and internal dependency.
In PMBOK 6.3.3.2, the example for internal dependency is team cannot test a machine until they assemble it.
In PMBOK 6.3.3.2, the example for mandatory dependency is the superstructure in construction project cannot be erected until foundation has been built.

My View:
Both examples above looks like Mandatory dependency. I am unable to understand internal dependency correctly.
I would be grateful if you can assist me in this regard.

[saket]

Mandatory and discretionary dependency categorization is to show how strong the dependency is. Internal / External is a categorization talks about is it from the team itself or from outside.

All Internal Dependencies will either be Mandatory or Discretionary and same is true for external dependencies

The Mandatory Dependency mean you can not overlook the relation, where as discretionary dependency mean it is recommended to follow this relation but if needed you may overlook it, when we work on develop schedule and apply fast tracking we overlook the discretionary dependency.