You could have downloaded nnBackup 2.2 from our software library for free. Commonly, this program's installer has the following filenames: cmd.exe and nnbackup.exe etc. This software is an intellectual property of nnSoft XXI. The most popular version among the program users is 2.2. The program lies within System Utilities, more precisely Backup & Restore.
From the developer:
nnBackup is a small (350k) and convenient command line tool for backing up and synchronizing your files and folders, creating and processing file-lists. When backing up you can optionally compress the data using internal gz/zip algorithms or your preferred external archiver and start specified applications before and after main backup process. nnBackup includes special tools for removing obsolete data from the backup.
You may want to check out more software, such as Simply Backup CDRW, StartDefrag or SAFE Block, which might be similar to nnBackup.