There is only one file type that uses the .NDA extension:
Nero Backup File
Backup file created by BackItUp (formerly BackItUp and Burn), a program that allows users to compress and back up files; contains encrypted backup data of your files, folders, applications, or drives.
To make a backup of your data, BackItUp and Burn creates multiple NDA files to store the data. You can only restore the file by using Nero's backup software.
|Nero BackItUp 2019||Paid|
Updated: February 27, 2016