Files with nns extension can be found as configuration files from NAVNET32 program by Symantec.
NNS file extension - NAVNET32 configuration data
What is nns file? How to open nns files?
File type specification:
The nns file extension is associated with the NAVNET32, an older program from Symantec company.
The nns file contains configuration data form Symantec NAVNET32.
Seems to be obsolete product without support from Symantec.
This nns file type entry was marked as obsolete and no longer supported file format.
This type of file is no longer actively used and is most likely obsolete. This is typically the case for system files in old operating systems, file types from long discontinued software, or previous versions of certain file types (like documents, projects etc.) that were replaced in higher versions of their original programs.