Due to an infrastructure change, FTP access to NVIDIA driver, source code, and documentation downloads is no longer available at ftp://download.nvidia.com. This change took place on April 28th, 2017.
The content currently hosted at ftp://download.nvidia.com will continue to be available at http://download.nvidia.com, and is now additionally available at https://download.nvidia.com.
NVIDIA recommends that any users previously downloading content from ftp://download.nvidia.com switch to using HTTPS instead, or HTTP if HTTPS support is not available.
[Edit: this transition is complete]