What is the default sample rate of NI-9220

[Den56]

What is the default sample rate of NI-9220 (using CVI).

if I don't use this function:  DAQmxCfgSampClkTiming();

[Den56]

     status1 = DAQmxGetTimingAttribute (dmmHandle, DAQmx_SampClk_Rate, &num, sizeof(num +5));   

num (the rate) = 0

how can this be 0 ?