Q1: What is the file extension used by WIN95 to back up registry file when windows starts?

ANS:B - .dao

A dao file store image at the (Disk at Once) - format. The DAO file type is primarily associated with Duplicator.

The DAO Misc file format

Files with the DAO extension are created using CD/DVD duplicator software. This software is used by devices and systems that allow the exact duplication of CDs or DVDs. They are even able to duplicate several discs at the same time. DAO files contain the exact duplicated information from either a CD or DVD and are used for the backup or distributional purposes.