The course of interview will be on you to decide. If you spill the beans early during the interview, it can go into an unintended direction so rather than explicitly stating that you did your degree through distance mode, simply say that you did xyz during your undergraduate studies and then quickly move on to the next thing you did after that.
While you're not disclosing everything, you're also not hiding anything. If the interviewer further asks what was the mode of your degree, then you can always clarify.
The idea is to speak thoughtfully about anything and that is applicable to any interview you'll appear for- job, business-school or when trying to tie the nuptial knots!