When an *.appcache file requires a NTLM authentication to, the appcache file fails to register as an application cache manifest, throwing the error "Application Cache manifest could not be fetched." In addition, even if the appcache file is placed outside of the NTLM authentication zone (anonymously accessible) and the appcache is recognized, any other file listed in the manifest that is also behind the NTLM authentication zone will also fail to be retrieved.
This leads me to believe that appcache retrievals (either the manifest or a listed file) are not passing the NTLM credentials along with with their requests. The user is first prompted for NTLM credentials on page load, so the page does have the credentials "somewhere" in context.
I have noticed this in Safari 8 & 9, on both OSX and iOS.
cool so were dropping safari support, thanks