155.21.32.0/20

Currently announced by AS1540 Headquarters, USAISC, in the routed prefix 155.21.32.0/20.

Routing data · Nov 1, 2026, 18:24 UTC

ASN historyEvery routed prefix covering 155.21.32.0/20

Prefix	ASN	Name	Registered country	First seen (UTC)	Last seen (UTC)	Status
155.21.32.0/20	AS1540	Headquarters, USAISC	United States	2026-10-31 10:23	2026-11-01 18:24	Announcing
155.21.32.0/19	AS749	United States Department of Defense (AS749)	United States	Before monitoring	2026-11-01 18:24	Announcing

No more specific routes inside this prefix.

Detected (UTC)	Prefix	Change	ASN	Name	Previous ASN	Country
2026-10-31 10:23	155.21.32.0/20	New announcement	AS1540	Headquarters, USAISC	—	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.