asn.dev

Autonomous system

AS33666 CMCS

Unclassified ARIN

IPv4 addresses 247K 89 prefixes
IPv6 prefixes 12 counted as prefixes, not addresses
Countries 1 mostly US
Exchanges 0 recorded by PCH
Upstreams 1 5 downstream
Flagged prefixes 0 none

Summary

Comcast Cable Communications

United States of America · AI-generated

residential cable isp us

The AS handle CMCS is held by Comcast Cable Communications, LLC.

What it's used for

  • The address space carries residential cable internet access, evidenced by reverse DNS entries such as c-67-177-80-0.hsd1.fl.comcast.net and c-68-35-208-0.hsd1.al.comcast.net.
  • With 247,296 IPv4 addresses announced across 89 prefixes and only 6 observed neighbours, the high address-to-neighbour ratio indicates this is an access network serving end-users rather than a transit provider.

Notable

  • Registrants are consistent with the announcer, appearing as both Comcast Cable Communications, LLC and Comcast Cable Communications, Inc. across the largest prefixes.
  • The inventory is finely subdivided into regional blocks, with netnames like TALLAHASSEE-1, JUMPSTART-1, and NORTH-GULF-21 reflecting site-by-site segmentation of the corporate estate.
  • The AS was first seen in RIS in 2007, indicating it has been active for nearly two decades.

This description is AI-generated, best-effort context — not authoritative, and provided without any guarantee of accuracy. Source, and how to suggest an edit.

Interconnection

Peering at a glance

Full topology · Graph

Internet exchanges

No exchange port on file. Many exchanges publish no participant list, so this is not proof of absence.

Transit providers

1 upstream, 5 downstream and 8 adjacent networks observed; most-used upstreams first.

ASNetworkPaths seen
AS7922Comcast Cable Communications, LLC273

Exchange presence is recorded rather than inferred: the directory collected by Packet Clearing House (https://www.pch.net/ixp/data) on 2026-10-24, licensed CC BY-NC-SA 3.0. Transit is inferred from observed BGP paths, never declared by either party.

Address space

Summary

Shape and geography

IPv4 89 prefixes · 247K addresses IPv6 12 prefixes

CountryNamePrefixes
USUnited States of America101

Registry

Allocation record

ARIN · via Atlas (registry + RDAP)
Registry
ARIN
Handle
AS33666
Registry name
CMCS
Registrant
Comcast Cable Communications, LLC
Abuse contact
abuse@comcast.net
Registered
2005-02-16
Last changed
2021-01-25
Allocation
assigned

Routing security

RPKI and IRR

Full detail
RPKI
50% valid · 3 valid, 3 with no ROA
ROAs
110 authorising AS33666
ASPA
no ASPA record
IRR
50% registered · 3 of 6 announcements 2 other origin
Route objects
109 naming AS33666

Reputation

Classification and threat

Unclassified Not in the curated lists. Most of the ~80,000 allocated ASNs are not.

Spamhaus DROP

Not on ASN-DROP The network as a whole is not listed.

No DROP prefixes None of its announced space is on the DROP prefix list.

Spamhaus DROP ("Don't Route Or Peer") lists space and networks run by, or hijacked for, spam and cybercrime operations: 442 networks and 1,779 prefixes, as published 2026-10-24. A short, high-confidence list, so a match is worth taking seriously, and absence from it says little on its own.

FBI IC3

No IC3 indicators Nothing from the FBI IC3 feed.

IC3 threat data is alpha. Absence of an indicator is not evidence of good behaviour, only of absence from this one feed.

Elsewhere

Cross-check