Django can't make external connections with requests or urllib2 on development server
It does seem that your server cannot resolve the hostname into IP, this is probably not Django nor Python problem but your server network setup issue.
Try to reach the same URL with ping tool / wget/curl or troubleshoot DNS with nslookup.
Everytime I make an external request (including to google.com) I get this response:
HTTPConnectionPool(host='EXTERNALHOSTSITE', port=8080): Max retries exceeded with url: EXTERNALHOSTPARAMS (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x105d8d6d0>: Failed to establish a new connection: [Errno 8] nodename nor servname provided, or not known',))