Envelope Files
The PS4 requests a number of .env files from Sony servers, they use some form of encryption so I am uncertain as to what they contain.
Here is a list of the ones I've logged on my PS4:
http://ps4-system.sec.np.dl.playstation.net/ps4-system/bgdc/np/v00/bgdc-config.xml.env http://ps4-system.sec.np.dl.playstation.net/ps4-system/bgft/np/v02/bgft.env http://ps4-system.sec.np.dl.playstation.net/ps4-system/hid_config/np/v00/hid_config.env http://ps4-system.sec.np.dl.playstation.net/ps4-system/netev/np/v00/netev-config.env http://ps4-system.sec.np.dl.playstation.net/ps4-system/sl-config/np/v06/sl-config.xml.env http://ps4-system.sec.np.dl.playstation.net/ps4-system/sl-config-dev/np/v06/sl-config-dev.xml.env http://ps4-system.sec.np.dl.playstation.net/ps4-system/sl-config-kamaji/np/v01/sl-config-kamaji.xml.env http://ps4-system.sec.np.dl.playstation.net/ps4-system/timezone/np/v00/timezone.dat.env http://ps4-system.sec.np.dl.playstation.net/ps4-system/wctl/np/v00/wctl-config.env