In /usr/portage/profiles/thirdpartymirrors we see: kernel http://www.kernel.org/pub http://www.us.kernel.org/pub http://www.de.kernel.org/pub http://www.fr.kernel.org/pub http://www.uk.kernel.org/pub http://www.at.kernel.org/pub all this sites except first one is no longer resolvable. Reproducible: Always
Thanks for reporting. Fixed.