asn.dev

Autonomous system

AS33660 CMCS - Comcast Cable Communications, LLC

Unclassified ARIN

IPv4 addresses 622K 96 prefixes
IPv6 prefixes 54 counted as prefixes, not addresses
Countries 1 mostly US
Exchanges 0 recorded by PCH
Upstreams 2 62 downstream
Flagged prefixes 0 none

Summary

Comcast

United States of America · AI-generated

cable residential 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 services, evidenced by reverse DNS entries like c-174-52-64-0.hsd1.ut.comcast.net and netnames such as UTAH-CPE-36.
  • With 622,080 IPv4 addresses announced across 97 prefixes and 69 observed neighbours, the high address-to-neighbour ratio indicates a large-scale access network rather than a transit provider.

Notable

  • Registrants consistently identify as Comcast Cable Communications, with minor variations in legal suffixes (Inc., LLC) across different prefix blocks.
  • The inventory is finely subdivided into numerous /17 and /18 blocks, reflecting site-by-site segmentation typical of a major cable operator's internal estate.
  • PeeringDB classifies the scope as Regional, specifically for the Utah market, aligning with the hsd1.ut domain in the reverse DNS records.

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

2 upstream, 62 downstream and 70 adjacent networks observed; most-used upstreams first.

ASNetworkPaths seen
AS7922Comcast Cable Communications, LLC1,971
AS3356Level 3 Parent, LLC20

Exchange presence is recorded rather than inferred: the directory collected by Packet Clearing House (https://www.pch.net/ixp/data) on 2026-11-03, 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 96 prefixes · 622K addresses IPv6 54 prefixes

CountryNamePrefixes
USUnited States of America150

Registry

Allocation record

ARIN · via Atlas (registry + RDAP)
Registry
ARIN
Handle
AS33660
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
95% valid · 55 valid, 3 with no ROA
ROAs
1,377 authorising AS33660
ASPA
no ASPA record
IRR
81% registered · 47 of 58 announcements 1 other origin
Route objects
106 naming AS33660

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: 448 networks and 1,851 prefixes, as published 2026-11-04. 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