147.51.0.0/16

Currently announced by AS1540 Headquarters, USAISC, in the routed prefix 147.51.0.0/16.

Routing data · Oct 22, 2026, 12:20 UTC

ASN historyEvery routed prefix covering 147.51.0.0/16

Prefix	ASN	Name	Registered country	First seen (UTC)	Last seen (UTC)	Status
147.51.0.0/16	AS1540	Headquarters, USAISC	United States	2026-10-22 02:18	2026-10-22 12:20	Announcing
147.51.0.0/16	AS367	United States Department of Defense (DoD)	United States	Before monitoring	2026-10-22 00:20	Stopped

Prefix	ASN	Name	Registered country	First seen (UTC)	Last seen (UTC)	Status
147.51.98.0/24	AS367	United States Department of Defense (DoD)	United States	Before monitoring	2026-10-22 08:21	Stopped

Detected (UTC)	Prefix	Change	ASN	Name	Previous ASN	Country
2026-10-22 02:18	147.51.0.0/16	Origin change	AS1540	Headquarters, USAISC	AS367	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.