AS21508
Comcast Cable Communications, LLC
Reputation · trust score
A transparent 0–100 signal. Every entity starts at a neutral baseline of 65; threat-intel blocklists, exposure, reverse-DNS, routing and allocation each adjust it up or down. Higher is more trustworthy.
- Baseline (neutral) 65
- Isp allocation +5
- Trust score 70 / 100
Experimental · trust-vectors model v1.2.0 — a transparent heuristic, not a definitive verdict. How it works →
About Xfinity
Comcast Cable Communications, doing business as Xfinity, is an American telecommunications business segment and division of Comcast Corporation. It is used to market consumer cable television, internet, telephone, and wireless services provided by the company.
Network profile
Source: PeeringDB →AS21508 — global IP footprint
Cities where AS21508 has measurable IPv4 allocation. Click any dot to open that city's page. Size and color scale with IP count.
Top CIDR ranges
BGP Announced Prefixes
Live BGP anomalies →Prefixes AS21508 actually originates in BGP, observed across our RIPE RIS collectors. This live routing view can differ from the registry allocation above.
| Prefix | Announcement samples | Last seen |
|---|---|---|
| 198.90.112.0/22 | 10,922 | 2026-07-25 06:53:27 |
| 157.240.148.0/24 | 8,923 | 2026-07-25 06:53:27 |
| 50.218.47.0/24 | 8,505 | 2026-07-25 06:53:27 |
| 50.205.217.0/24 | 6,923 | 2026-07-25 06:53:00 |
| 50.204.101.0/24 | 6,910 | 2026-07-25 06:53:27 |
| 50.229.113.0/24 | 6,893 | 2026-07-25 06:52:11 |
| 50.217.207.0/24 | 6,884 | 2026-07-25 06:53:56 |
| 50.235.34.0/24 | 6,882 | 2026-07-25 06:52:48 |
| 50.229.114.0/24 | 6,881 | 2026-07-25 06:52:11 |
| 50.216.229.0/24 | 6,868 | 2026-07-25 06:51:53 |
| 50.217.1.0/24 | 6,857 | 2026-07-25 06:52:11 |
| 50.228.113.0/24 | 6,823 | 2026-07-25 06:52:48 |
| 157.240.147.0/24 | 6,794 | 2026-07-25 06:54:26 |
| 141.104.0.0/16 | 6,744 | 2026-07-25 06:54:26 |
| 205.223.19.0/24 | 6,738 | 2026-07-25 06:54:26 |
| 173.242.174.0/24 | 6,697 | 2026-07-25 06:53:56 |
| 204.194.47.0/24 | 6,686 | 2026-07-25 06:53:27 |
| 50.219.12.0/22 | 4,152 | 2026-07-13 06:46:19 |
Frequently Asked Questions
What is AS21508?
AS21508 is an Autonomous System Number assigned to Comcast Cable Communications, LLC. An ASN identifies a network that controls a specific set of IP addresses and determines how traffic is routed across the internet via BGP (Border Gateway Protocol).
How many IP addresses does AS21508 announce?
AS21508 announces 71.4K IPv4 addresses distributed across 18 routed CIDR prefixes. The network is registered in United States.
Who operates AS21508?
AS21508 is operated by Comcast Cable Communications, LLC. The organization is based in United States. You can view all IP ranges and related ASNs on the organization page.
What country is AS21508 registered in?
AS21508 is registered in United States. This indicates where the network operator is headquartered, though the IP addresses it announces may serve users globally.
