How to fix the March 2017 Ubuntu DNS resolution issues

As of March 20th, many Ubuntu users across the web were suddenly having DNS resolution issues pop up in their applications due to a bad update pushed out by Canonical (the maintainers of Ubuntu) which breaks DNS resolution after a few hours of uptime. Here’s the bug report where the issue was reported and triaged:

https://bugs.launchpad.net/ubuntu/+source/eglibc/+bug/1674532

This may have resulted in failures of your CMS to update/install plugins/install themes, failures to connect to external APIs, and/or error messages similar to the following:

Warning: file_get_contents(): php_network_getaddresses: getaddrinfo failed: No address associated with hostname

Could not resolve host: downloads.wordpress.org

cURL error 6: Could not resolve host: example.com in....

Fortunately Canonical has since been able to resolve the issue, but affected systems must update to acquire the fix. To do that, you’ll need DNS working, so if it’s currently down please first reboot your Droplet. Once DNS resolution is working as normal, please run:

sudo apt-get update
sudo apt-get upgrade

Then you can check your versions to ensure you’ve got the right ones. This can be done with:

sudo dpkg -l | grep "GNU C Library" | awk '{print $3}'

If you’re on Ubuntu 16.X, you should see output similar to the following:

# sudo dpkg -l | grep "GNU C Library" | awk '{print $3}'
2.23-0ubuntu7
2.23-0ubuntu7
2.23-0ubuntu7

If you’re on Ubuntu 14.X, you should see output similar to the following:

# sudo dpkg -l | grep "GNU C Library" | awk '{print $3}'
2.19-0ubuntu6.11
2.19-0ubuntu6.11

If you’re on Ubuntu 12.X, you should see output similar to the following:

# sudo dpkg -l | grep "GNU C Library" | awk '{print $3}'
2.15-0ubuntu10.17
2.15-0ubuntu10.17

If you see older versions of those packages, you’ll need to upgrade per the previous instructions to avoid this issue.

If you have further questions, please don’t hesitate to comment below or open a ticket! We’re happy to help :)

Regards, Darian Platform Support Advocate