SYNC

The SYNC variable - in - used to contain a rsync server URI to be used when updating the Portage tree. It has been depreciated in favor of using a modular sync system defined in

A list of community mirrors is maintained on the Gentoo site.

Choosing a mirror
A good rsync mirror can make Portage download source code (distfiles) faster. Choosing a mirror with the mirrorselect tool is generally a good idea.