AD9154 phase noise, DAC clock specification

The AD9154 specification documents the DAC output phase noise in Figure. 33 (PLL off). A 2.0 GHz DAC clock was externally supplied. Questions

1) What was the phase noise of the 2.0 GHz generator used in this test? 

2) Is the observed phase noise limited by the AD9154 or the generator? 

2) What is the maximum tolerable phase noise to achieve the performance in Figure 33?