For indoor runs through wall cavities Cat 6, UTP (unshielded twisted pair), solid copper, at least CM rated. Do not use stranded cable. This is what I use: Cat6 Ethernet Bulk Cable - Solid, 500Mhz, UTP, CMR, Riser Rated, Pure Bare Copper Wire, 23AWG, 1000ft, Blue - Monoprice.com This is CMR...