a0494a2a_ng__404_Not_Found_Error__Files__Category
[Comments and examples] Files added to the site (often in the root) to verify site ownership (e.g. advertising services, webmaster tools, uptime and anti-malware monitoring) are re-requested by the originating site but have been removed. [Category] 
Ownership Verification
Benign Unexpected URLs - Part 1 - Missing (404 Not Found Error) Files