When you configure an SLA item in CRM, you have the option to specify the “Failure” and “Warning” times as a duration.
The format of these fields Is the same as any other CRM duration field, but what does it really mean? For example, if you set it to 10 days, is it 10 calendar days? Is it 10 business days? You might be surprised it is neither!
Continued on Source: Gonzalo Ruiz - Dynamics CRM: CRM SLA Failure and Warning times, not what you would expect!