144.121.0.0/18

Currently announced by AS46887 Crown Castle, in the routed prefix 144.121.0.0/18.

Current ASN: AS46887; Crown Castle
Routed prefix: 144.121.0.0/18; Most specific route covering this prefix
ASNs over time: 1; 2 announcement records
RIR allocation: ARIN; United States · 144.121.0.0/16

Routing data · Nov 2, 2026, 00:27 UTC

ASN historyEvery routed prefix covering 144.121.0.0/18

Prefix	ASN	Name	Registered country	First seen (UTC)	Last seen (UTC)	Status
144.121.0.0/18	AS46887	Crown Castle	United States	Before monitoring	2026-11-02 00:27	Announcing
144.121.0.0/16	AS46887	Crown Castle	United States	Before monitoring	2026-11-02 00:27	Announcing

More specific routes19 total

Prefix	ASN	Name	Registered country	First seen (UTC)	Last seen (UTC)	Status
144.121.0.0/22	AS46887	Crown Castle	United States	Before monitoring	2026-11-02 00:27	Announcing
144.121.4.0/22	AS46887	Crown Castle	United States	Before monitoring	2026-11-02 00:27	Announcing
144.121.8.0/22	AS46887	Crown Castle	United States	Before monitoring	2026-11-02 00:27	Announcing
144.121.12.0/22	AS46887	Crown Castle	United States	Before monitoring	2026-11-02 00:27	Announcing
144.121.16.0/22	AS46887	Crown Castle	United States	Before monitoring	2026-11-02 00:27	Announcing
144.121.20.0/22	AS46887	Crown Castle	United States	Before monitoring	2026-11-02 00:27	Announcing
144.121.24.0/22	AS46887	Crown Castle	United States	Before monitoring	2026-11-02 00:27	Announcing
144.121.27.0/24	AS15027	Foley Hoag LLP	United States	Before monitoring	2026-11-02 00:27	Announcing
144.121.28.0/22	AS46887	Crown Castle	United States	Before monitoring	2026-11-02 00:27	Announcing
144.121.30.0/24	AS62653	Housing Authority Risk Retention Group, Inc.	United States	Before monitoring	2026-11-02 00:27	Announcing
144.121.32.0/21	AS46887	Crown Castle	United States	Before monitoring	2026-11-02 00:27	Announcing
144.121.40.0/24	AS46887	Crown Castle	United States	Before monitoring	2026-11-02 00:27	Announcing
144.121.41.0/24	AS46887	Crown Castle	United States	Before monitoring	2026-11-02 00:27	Announcing
144.121.43.0/24	AS64293	Mobile Heartbeat	United States	Before monitoring	2026-11-02 00:27	Announcing
144.121.44.0/22	AS46887	Crown Castle	United States	Before monitoring	2026-11-02 00:27	Announcing
144.121.48.0/20	AS46887	Crown Castle	United States	Before monitoring	2026-11-02 00:27	Announcing
144.121.49.0/24	AS46887	Crown Castle	United States	Before monitoring	2026-11-02 00:27	Announcing
144.121.61.0/24	AS27015	FRESENIUS MEDICAL CARE HOLDINGS, INC	United States	Before monitoring	2026-11-02 00:27	Announcing
144.121.35.0/24	AS46887	Crown Castle	United States	2026-10-21 22:21	2026-10-30 16:19	Stopped

Change logAll changes

The routes covering this address have had no origin changes since ASNBase started monitoring.

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RIR allocation record

Registry: ARIN
Allocated block: 144.121.0.0/16
Country: United States
Allocation date: 2016-04-29
Status: allocated

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

How monitoring works

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.