AS9457 DREAMX-AS DREAMLINE CO.

AS9457 (DREAMX-AS) is held by Dreamline Co., Ltd. (드림라인), a South Korean telecom operator founded in 1997 that builds and runs its own nationwide fibre backbone. Its business today is business-to-business: leased lines, dedicated internet access, data-centre (IDC) services, business messaging and tower/utility network services. Despite the address footprint, it is not a consumer broadband ISP.

What it's used for

RIS observes 110 IPv4 prefixes covering roughly 900,000 addresses, one IPv6 prefix (2001:c48::/32), and 57 BGP neighbours. The IPv4 space is dominated by whole classful-era /16s — 121.53.0.0/16, 220.230.0.0/16, 61.107.0.0/16, 211.249.0.0/16 and more — the kind of large contiguous blocks a network only gets by having been an eyeball provider early.

That is exactly the history: Dreamline built a national network in 1998 and sold consumer high-speed internet in the Seoul region, but handed the entire consumer broadband business to Hanaro Telecom in 2003 when SeAH Group took over the company. The /16s stayed. The customers did not. What the space carries now is enterprise dedicated-line customers, IDC/colocation tenants, and wholesale connectivity — its named customer base runs to mobile carriers, other ISPs, financial institutions and IT companies, and it is an AWS Direct Connect partner.

Fifty-seven neighbours on ~900k addresses is the middle ground the evidence points to: too many peers for a pure end-site, far too few for a tier-1 transit carrier. It is a mid-sized national carrier reselling connectivity and hosting.

Notable

• PeeringDB still lists this network as "Cable/DSL/ISP" with 100–200 Gbps of balanced traffic. That label is more than two decades stale — the retail broadband business was divested in 2003 — and is a good example of a directory entry describing a company's past rather than its inventory.
• Ownership has changed repeatedly: a Korea Expressway Corporation / CJ joint venture at founding, then Hanaro Telecom, then SeAH Group, then the private-equity firm EQ Partners in December 2014.