When are All GameObject Awake(), OnEnable(), Start() called?

 1.

ExLifeCycle script is attached into All GameObjects (ex: Parent, Child1, ... )

public class ExLifeCycle : MonoBehaviour
{
private void Awake()
{
Debug.Log($"{name}:Awake");
}

private void OnEnable()
{
Debug.Log($"{name}:OnEnable");
}
void Start()
{
Debug.Log($"{name}:Start");
}

}

When Playing, the follow logs comes

----------------------

Child1:Awake

Child1:OnEnable

SubChild(1):Awake

SubChild(1):OnEnable

Child1(3):Awake

Child1(3):OnEnable

Parent:Awake

Parent:OnEnable

Child1(2):Awake

Child1(2):OnEnable

.....

Child1:Start

SubChild(1):Start

...

the calling order of GameObject Awake,Enable is not fixed, and random.

and After All gameObject OnEnable() are called, Start() of all are called.

2.

when playing unity in this case, 

SubChild:Awake

SubChild:OnEnable

Child1(2):Awake

Child1(2):OnEnable

SubChild:Start

Child1(2):Start

are not printed in console.

.