$ query “AS21508” --type=asn → 1 result(s)

AS21508 · COMCAST-21508

Comcast Cable Communications LLC

AS21508 is operated by Comcast Cable Communications LLC and serves as a mid-size transit provider, established in the United States in 2001. The system announces a respectable 71 424 IPv4 addresses, including a /16, and supports IPv6. Most of its address space is geolocated to the United States.

  • Top 5% — Top 5% of all autonomous systems by reach and degree

Basic Information

Country
🇺🇸 United States
Category
Internet Service Provider
Network Role
Mid-size Transit
Data Origin
Authoritative — Metadata from authoritative RIR registry (ARIN, RIPE, APNIC, etc.)
Registered
May 16, 2001
Last Changed
March 04, 2026
Last Seen
April 28, 2026 (active)

Prefix Summary

IPv4 Prefixes (raw / aggregated)
18 / 18
IPv6 Prefixes (raw / aggregated)
64 / 61
IPv4 Addresses
71 424
Largest IPv4 Prefix
/16 (65 536 addresses)
Largest IPv6 Prefix
/47
Geolocated Countries
🇺🇸 United States (136 960 IPs)
Prefix Changed
April 17, 2026

Reputation

Reputation
Pristine — 0 flagged IPs

Connectivity Summary

Upstream Providers
1 upstream providing transit
Downstream Customers
46 downstreams buying transit
Unclassified
1 unclassified BGP neighbor
Degree
48 unique BGP neighbors
Reach
36 614 networks in customer cone

Upstream Providers (1)

Prefix Lists

IPv4 Prefixes (18 total)

  • 141.104.0.0/16 (65 536 addresses (/16 prefix))
  • 50.219.12.0/22 (1 024 addresses (/22 prefix))
  • 198.90.112.0/22 (1 024 addresses (/22 prefix))
  • 50.229.113.0/24 (256 addresses (/24 prefix))
  • 50.235.34.0/24 (256 addresses (/24 prefix))
  • 50.218.47.0/24 (256 addresses (/24 prefix))
  • 50.217.1.0/24 (256 addresses (/24 prefix))
  • 50.228.113.0/24 (256 addresses (/24 prefix))
  • 50.204.101.0/24 (256 addresses (/24 prefix))
  • 50.229.114.0/24 (256 addresses (/24 prefix))
  • 50.217.207.0/24 (256 addresses (/24 prefix))
  • 50.216.229.0/24 (256 addresses (/24 prefix))
  • 157.240.147.0/24 (256 addresses (/24 prefix))
  • 157.240.148.0/24 (256 addresses (/24 prefix))
  • 173.242.174.0/24 (256 addresses (/24 prefix))
  • 50.205.217.0/24 (256 addresses (/24 prefix))
  • 204.194.47.0/24 (256 addresses (/24 prefix))
  • 205.223.19.0/24 (256 addresses (/24 prefix))

IPv6 Prefixes (64 total)

  • 2001:559:49a::/47
  • 2001:559:c0f6::/47
  • 2001:559:c4c8::/47
  • 2001:559:8a::/48
  • 2001:559:c0::/48
  • 2001:559:f7::/48
  • 2001:559:220::/48
  • 2001:559:243::/48
  • 2001:559:280::/48
  • 2001:559:37d::/48
  • 2001:559:3ac::/48
  • 2001:559:3b9::/48
  • 2001:559:3c8::/48
  • 2001:559:40a::/48
  • 2001:559:53c::/48
  • 2001:559:5c9::/48
  • 2001:559:5db::/48
  • 2001:559:72b::/48
  • 2001:559:73c::/48
  • 2001:559:788::/48
  • 2001:559:78a::/48
  • 2001:559:79d::/48
  • 2001:559:79e::/48
  • 2001:559:7a7::/48
  • 2001:559:7db::/48
  • 2001:559:804c::/48
  • 2001:559:81bf::/48
  • 2001:559:81d7::/48
  • 2001:559:81d8::/48
  • 2001:559:8201::/48
  • 2001:559:82fd::/48
  • 2001:559:833e::/48
  • 2001:559:8416::/48
  • 2001:559:841c::/48
  • 2001:559:8445::/48
  • 2001:559:84a7::/48
  • 2001:559:8535::/48
  • 2001:559:85c1::/48
  • 2001:559:85ff::/48
  • 2001:559:8604::/48
  • 2001:559:871a::/48
  • 2001:559:875f::/48
  • 2001:559:8773::/48
  • 2001:559:87b2::/48
  • 2001:559:c071::/48
  • 2001:559:c10a::/48
  • 2001:559:c174::/48
  • 2001:559:c1a5::/48
  • 2001:559:c1ca::/48
  • 2001:559:c28f::/48
  • and 11 more