Consumer ISP
AS21508 COMCAST-21508ASN lookup: IP ranges, prefixes and network type
AS21508 is the autonomous system number (ASN) announced by COMCAST-21508. It announces 86 prefixes, 72,448 IPv4 addresses in total. Every address inside those ranges is routed by this operator, which is what makes the number the shortest answer to who runs a given address.
AS21508 at a glance
| Organisation | COMCAST-21508 |
|---|---|
| Autonomous system | AS21508 |
| Network type | Consumer ISP |
| IPv4 prefixes | 21 |
| IPv6 prefixes | 65 |
| IPv4 addresses | 72,448Summed across every announced prefix. IPv6 is not counted; the numbers are meaningless at that scale. |
| In known VPN ranges | 0 of 21 prefixes |
| In known datacenter ranges | 0 of 21 prefixes |
The last two rows are a second opinion, counted against the X4BNet VPN and datacenter range lists rather than read off the operator name. A network with most of its prefixes in the VPN list is carrying anonymised traffic whatever it calls itself.
Sample prefixes
The largest ranges COMCAST-21508 announces, biggest first. These are a sample and not the full routing table: 86 prefixes do not fit on a page, and the ones worth showing are the ones most traffic comes from.
| Prefix | Family | Addresses |
|---|---|---|
| 141.104.0.0/16 | IPv4 | 65,536 |
| 50.219.12.0/22 | IPv4 | 1,024 |
| 198.90.112.0/22 | IPv4 | 1,024 |
| 50.229.232.0/23 | IPv4 | 512 |
| 50.204.101.0/24 | IPv4 | 256 |
| 50.205.217.0/24 | IPv4 | 256 |
| 50.216.229.0/24 | IPv4 | 256 |
| 50.217.1.0/24 | IPv4 | 256 |
| 50.217.207.0/24 | IPv4 | 256 |
| 50.218.47.0/24 | IPv4 | 256 |
| 50.220.111.0/24 | IPv4 | 256 |
| 50.227.24.0/24 | IPv4 | 256 |
Look up an address on AS21508
The field is prefilled with 141.104.0.1, the first address of the largest range above. Change it for one from your own logs and you get the network, the operator and the verdict for that specific address.
What AS21508 means for detection
Addresses on COMCAST-21508 are consumer connections: households and small businesses on a fixed line. Our engine classifies them residential, which is the class most likely to be a real customer, and the class fraud tools are least likely to flag. The catch is the residential proxy. An address here can be rented out by whoever holds the connection, and when that happens the ownership data on this page still reads as clean. That is a behavioural signal, not an ownership one.
The verdict for a single address is never settled by the ASN alone. It is the starting point, and IP Detection adds range membership, behaviour and history on top of it before it answers.
Related networks
The same page as JSON
No key and no signup. This is the endpoint this page is rendered from, so anything you read here you can script against.
curl https://ipscanner.io/v1/asn/directory/AS21508
IPScanner. AS21508 COMCAST-21508, ASN directory. https://ipscanner.io/es/asn/as21508. Derived from MaxMind GeoLite2.