We've just now made a change to the dist.plone.org IP address. Hopefully you will not notice anything when you next run buildout! Both http and https seem to be working to the new IP address. This change was necessary to prepare for a physical server move.
If you run into any issues connecting with dist.plone.org, please respond here or via email to admins@plone.org
We thank Six Feet Up for continuing to help Plone by serving both dist.plone.org and old.plone.org!