sudo apt -o Debug::Acquire::http=true update
0% [Working]GET /steam/dists/precise/InRelease HTTP/1.1
Host: repo.steampowered.com
Cache-Control: max-age=0
Accept: text/*
If-Modified-Since: Wed, 30 Mar 2016 19:35:17 GMT
User-Agent: Debian APT-HTTP/1.3 (1.2.10)
Answer for: http://repo.steampowered.com/steam/dists/precise/InRelease
HTTP/1.1 304 Not Modified
Last-Modified: Wed, 30 Mar 2016 19:35:17 GMT
ETag: "2c060e-b1a-52f493ed7c740"
Cache-Control: public, must-revalidate, max-age=3600
Date: Fri, 08 Apr 2016 14:43:59 GMT
Connection: keep-alive
Hit:1 http://repo.steampowered.com/steam precise InRelease
0% [1 InRelease gpgv 2,842 B] [Connecting to archive.ubuntu.com (2001:67c:1360:8001::17)] [Connecting to us.archive.ubuntu.com (2001:67c:1562::15)] [Connecting to archive.canonical.cGET /graphics-drivers/ppa/ubuntu/dists/xenial/InRelease HTTP/1.1
Host: ppa.launchpad.net
Cache-Control: max-age=0
Accept: text/*
If-Modified-Since: Thu, 07 Apr 2016 10:20:22 GMT
User-Agent: Debian APT-HTTP/1.3 (1.2.10)
0% [Connecting to archive.ubuntu.com (2001:67c:1360:8001::17)] [Connecting to us.archive.ubuntu.com (2001:67c:1562::15)] [Connecting to archive.canonical.com (2001:67c:1360:8c01::16)Answer for: http://ppa.launchpad.net/graphics-drivers/ppa/ubuntu/dists/xenial/InRelease
HTTP/1.1 304 Not Modified
Date: Fri, 08 Apr 2016 14:43:59 GMT
Server: Apache
ETag: "5870f26-467e-52fe26d17d2a6"
Expires: Fri, 08 Apr 2016 14:43:59 GMT
Cache-Control: max-age=0, s-maxage=270, proxy-revalidate
Hit:2 http://ppa.launchpad.net/graphics-drivers/ppa/ubuntu xenial InRelease
0% [Connecting to archive.ubuntu.com (2001:67c:1562::15)] [Connecting to us.archive.ubuntu.com (2001:67c:1562::14)] [Connecting to archive.canonical.com (2001:67c:1360:8c01::1b)]