Docker apt-get some index files failed to download.

When I do sudo apt-get update, I get the following errors: E: Some index files failed to download, they have been ignored, or old ones used 

Dec 1, 2016 The error is obvious you can't connect to URL ph.archive.ubuntu.com so go to /etc/apt/ and search for ph.archive.ubuntu.com and disable it by  Stardog is the world's leading Enterprise Knowledge Graph.