Network · AS21508

AS21508 Comcast Cable Communications, LLC

AS21508 (Comcast Cable Communications, LLC) looks like an internet service provider, so its addresses are mostly real home, business or mobile connections.

Network check ASN

AS21508

OwnerComcast Cable Communications, LLC
KindInternet service provider
Servers, not peopleno
IPv4 addresses70,144
IPv4 ranges16
IPv6 ranges52

Risk score0

Nothing suspicious found.

Largest IPv4 ranges

141.104.0.0/16
198.90.112.0/22
50.235.34.0/24
50.229.114.0/24
50.229.113.0/24
50.228.113.0/24
50.218.47.0/24
50.217.207.0/24
50.217.1.0/24
50.216.229.0/24
50.205.217.0/24
50.204.101.0/24

Ranges and owner from DB-IP (CC BY 4.0), updated 2026-10-21.

Check an IP address →

Detect it in code

Spot AS21508 traffic at signup.

Send the visitor's IP. The response includes the ASN, the owner and flags.hosting.

curl https://veqen-app.com/v1/ip/check \
  -H "Authorization: Bearer $VEQEN_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"ip": "203.0.113.7"}'

import os, requests

r = requests.post(
    "https://veqen-app.com/v1/ip/check",
    headers={"Authorization": f"Bearer {os.environ['VEQEN_API_KEY']}"},
    json={"ip": "203.0.113.7"},
    timeout=10,
)
result = r.json()
print(result["risk"]["verdict"], result["risk"]["reasons"])

const res = await fetch("https://veqen-app.com/v1/ip/check", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.VEQEN_API_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({"ip": "203.0.113.7"}),
});
const result = await res.json();
console.log(result.risk.verdict, result.risk.reasons);

Questions

About AS21508

Is AS21508 a datacenter or VPN network?

AS21508 (Comcast Cable Communications, LLC) looks like an internet service provider, so its addresses are mostly real home, business or mobile connections.

Who owns AS21508?

AS21508 is registered to Comcast Cable Communications, LLC. It announces about 70,144 IPv4 addresses.

How do I detect traffic from AS21508?

Call the Veqen IP check with the visitor's address. The response includes the ASN, the owner and whether the network is a datacenter, VPN network, relay or ISP.