143.204.112.0/21

Currently announced by AS16509 Amazon.com, in the routed prefix 143.204.112.0/21.

Routing data · Nov 1, 2026, 20:20 UTC

ASN historyEvery routed prefix covering 143.204.112.0/21

Prefix	ASN	Name	Registered country	First seen (UTC)	Last seen (UTC)	Status
143.204.112.0/21	AS16509	Amazon.com	United States	2026-10-30 02:20	2026-11-01 20:20	Announcing

Prefix	ASN	Name	Registered country	First seen (UTC)	Last seen (UTC)	Status
143.204.112.0/24	AS16509	Amazon.com	United States	Before monitoring	2026-10-30 04:19	Stopped
143.204.113.0/24	AS16509	Amazon.com	United States	Before monitoring	2026-10-30 00:19	Stopped
143.204.114.0/24	AS16509	Amazon.com	United States	Before monitoring	2026-10-30 04:19	Stopped
143.204.115.0/24	AS16509	Amazon.com	United States	Before monitoring	2026-10-30 04:19	Stopped
143.204.116.0/24	AS16509	Amazon.com	United States	Before monitoring	2026-10-30 04:19	Stopped
143.204.117.0/24	AS16509	Amazon.com	United States	Before monitoring	2026-10-30 04:19	Stopped
143.204.118.0/24	AS16509	Amazon.com	United States	Before monitoring	2026-10-30 04:19	Stopped
143.204.119.0/24	AS16509	Amazon.com	United States	Before monitoring	2026-10-30 04:19	Stopped

Detected (UTC)	Prefix	Change	ASN	Name	Previous ASN	Country
2026-10-30 02:20	143.204.112.0/21	New announcement	AS16509	Amazon.com	—	United States

From the RIRs’ delegated statistics files. Shows where the addresses are registered, not where they are used.

Every 2 hours ASNBase takes the bgp.tools global routing table (prefix → origin ASN) and compares it with the previous one. The detected time is the time of that comparison; the actual change can be up to about 2 hours earlier.
Only routes seen by more than 100 bgp.tools peers are listed as changes; routes with less visibility are only kept in the history.
A new announcement counts only if it is still in the next routing table, and a withdrawal only if the prefix is missing from two tables in a row, so short flaps are ignored.
ASNBase has been monitoring since 2026-10-19. “Before monitoring” under “First seen” means the route was already announced when monitoring started; the earlier date is unknown.
Prefixes first seen during the first day of monitoring do not count as new announcements: most of them were simply missing from the table at the moment monitoring started.
Countries and regions follow the ASN’s registration, not the actual location of the IP addresses.