Home ASN LookupAS21508

AS21508 COMCAST-21508 - Comcast Cable Communications, LLC

🇺🇸

ARINassigned

Announced Prefixes (BGP)

219total

144 IPv475 IPv6

IPv4 Addresses

Allocated (RIR)65,536

Announced (BGP)690,432

IPv6 Addresses

Allocated (RIR)0

Announced (BGP)1×10³¹

Prefix Limit (IPv4)

500

Prefix Limit (IPv6)

500

Country

🇺🇸 US

RIR

ARIN

Status

assigned

Allocated

2001-05-16

Announced Prefixes

(BGP)219

Prefix	RPKI	IRR	Last Seen
23.25.96.0/19	Valid	-	2026-10-11
23.25.186.0/23	Valid	-	2026-10-11
23.31.96.0/20	Valid	-	2026-10-11
24.124.151.0/24	Valid	-	2026-10-11
24.124.162.0/23	Valid	-	2026-10-11
24.124.248.0/21	Valid	-	2026-10-11
24.131.0.0/20	Valid	Other IRR	2026-10-11
50.73.8.0/22	Valid	-	2026-10-11
50.73.224.0/20	Valid	-	2026-10-11
50.77.72.0/21	Valid	-	2026-10-11

1-10 of 219

1 / 22

Allocated Prefixes

(RIR)1

Prefix	Country	RIR	Status
141.104.0.0/16	🇺🇸 US	ARIN	allocated

All 219 announced prefixes of AS21508 →

BGP Neighbours

(seen in AS paths)

Upstreams (1)

Networks AS21508 hands its own prefixes to: transit providers, or peers at an exchange.

AS7922Comcast Cable Communications219

Downstreams (21)

Networks whose own prefixes AS21508 passes on: usually its customers.

AS13335Cloudflare4
AS15297EPLUS3
AS15173Newmarket Corporation2
AS54113Fastly2
AS394058Telos Corporation2
AS396083Framatome2
AS400114Apogee Telecom2
AS401426St. Marys Medical Center2
AS10794Bank Of America, National Association1
AS11739Digital Fortress1
AS30299THE MARTIN AGENCY1
AS32540HP Hood1
AS36040Google1
AS36364Mary Washington Hospital1
AS54219Matthews International Corporation1
AS54883City Of Richmond, Virginia1
AS393613Virginia Credit Union1
AS394276TurnAround Factor1
AS397190WSP1
AS399099Petersburg City Public Schools1
AS402549Terraservers1

Other adjacent networks (1)

Adjacent to AS21508 in the transit part of AS paths: peers, providers or customers.

AS399938Berkshire Hathaway Energy Company1

Transfer History

Registry transfers of AS21508 between organisations.

AS21508M&A · 2016-08-31
Comcast Cable Communications Holdings, Inc
🇺🇸 US ARIN
→
Comcast Cable Communications, LLC
🇺🇸 US ARIN

Date	Resource	From	To	Type
2016-08-31	AS21508	Comcast Cable Communications Holdings, Inc 🇺🇸 US ARIN	Comcast Cable Communications, LLC 🇺🇸 US ARIN	M&A

ASPA

No ASPA

External Links

ARIN Whois RIPEstat

Learn more

What is an ASN?Autonomous systems, ASN ranges and how they are assigned
RPKI and route origin validationWhat the RPKI badges on the prefix list mean
ASPA explainedWhy AS21508 should publish an ASPA object
IPv4 transfers in the ARIN regionMonthly volume and the latest registry transfers
ASN data in AI agents and SIEMMCP server and API integrations

API

Open

GEThttps://api.ipctl.io/v1/asn/21508

Returns ASN details, announced prefixes, and BGP routing data.

curl -s "https://api.ipctl.io/v1/asn/21508" | jq