What happens during the interview for the DV lottery immigrant Visa?

Question

I will be scheduled for an interview to apply for the visa as a dv lottery winner for dv 2009.

I want to know what exactly happens during the interview form anyone who has a previous experience and how long it is , what they ask for and what the reasoons for the refusing the visa are.

Answer 1

They want to check your original of the High school certificate.

Your medical.

Your Sponsor person details.

Your Backround and activities.

Any of these can be a reason for the visa refusal.