AS7725 COMCAST-7725

COMCAST-7725 is one of Comcast's secondary ASNs, registered to Comcast Cable Communications, LLC of Mt Laurel, New Jersey. Despite the famous name, it is not the Comcast residential eyeball network.

What it's used for

• It originates a few dozen scattered /22–/24 routes on behalf of Comcast Business dedicated-internet customers — enterprise sites that hold their own address space and have Comcast announce it for them.
• Sampling the ARIN registrations behind those prefixes turns up unrelated third-party organisations: a hospital, a state technical-college system, an industrial software vendor, an agribusiness, and several private companies. Only a handful of the prefixes are registered to Comcast itself, under Comcast Business netnames.
• There is essentially no reverse DNS across the space. Comcast's actual subscriber network is blanketed in c-IP-ADDR.hsd1.STATE.comcast.net names; none of that appears here.

Notable

• Do not treat this as consumer broadband address space. The residential eyeball network is [AS7922](https://asn.ipinfo.app/AS7922); Comcast Business runs separately on [AS7016](https://asn.ipinfo.app/AS7016). AS7725 is a third thing again: a routing vehicle for customer-held prefixes.
• Because the prefixes belong to distinct end-customer organisations rather than to Comcast, they should not be geolocated to Comcast or to a single Comcast market. Each one lands wherever that customer's site is.
• PeeringDB lists the network as "Comcast - Atlanta" and types it as Cable/DSL/ISP. The announced inventory does not support that reading, and the inventory is the more reliable witness.

Interesting

• ARIN registered the ASN on 1996-12-20, in the era when Comcast was still assembling its online business. The number survived every subsequent merger and rebrand while being quietly repurposed for enterprise customer routes.