AS10010 TOKAI TOKAI Communications Corporation

TOKAI is TOKAI Communications Corporation, the telecom subsidiary of TOKAI Holdings, headquartered in Shizuoka City. It is the ISP behind the nationwide @T COM brand and the Shizuoka-local TNC (TOKAI Network Club) brand, and it grew out of a cable-TV business, which is still part of the group.

What it's used for

Consumer and small-business broadband. The AS announces 187 IPv4 prefixes totalling roughly 1,503,000 addresses and 7 IPv6 prefixes — a very large pool of access space, mostly in /16s and /17s. Every sampled address lands in a subscriber pool: 5.net042126000.t-com.ne.jp and p005.net182020128.tnc.ne.jp bake the customer's IPv4 address into the hostname, which is what CPE naming looks like at scale, and both zones are the operator's own retail brands.

Notable

An eyeball network, and one of the larger regional ones in Japan. The decisive evidence is the ratio: 1.5 million addresses against only 63 observed BGP neighbours. A wholesale carrier holding that much space would peer with hundreds to thousands of ASes; a retail ISP buys transit from a few upstreams and peers at a couple of exchanges. Geolocate this space to Japanese households, concentrated in Shizuoka and the wider Tokai region but present nationally through @T COM.

Interesting

The sample also turns up sbtmwan-128.5.dws.ne.jp and i2059133.icntv.ne.jp — other operators' zones inside TOKAI's announced space. TOKAI sells wholesale connectivity and CATV-ISP services to smaller cable companies, so some of these addresses front third-party retail brands rather than @T COM directly.