SYNC

The  variable located in  contained a rsync server URI used when updating the Portage tree. It has been depreciated in favor of using a modular sync system defined in

A list of community rsync mirrors is still 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.