38.236.128.0/20

Currently announced by AS174 Cogent Communications, Inc., in the routed prefix 38.236.128.0/19.

Current ASN: AS174; Cogent Communications, Inc.
Routed prefix: 38.236.128.0/19; Most specific route covering this prefix
ASNs over time: 2; 4 announcement records
RIR allocation: ARIN; United States · 38.0.0.0/8

Routing data · Nov 1, 2026, 22:23 UTC

ASN historyEvery routed prefix covering 38.236.128.0/20

Prefix	ASN	Name	Registered country	First seen (UTC)	Last seen (UTC)	Status
38.236.128.0/20	AS52772	Sjnet Telecom	Brazil	Before monitoring	2026-10-30 00:19	Stopped
38.236.128.0/19	AS174	Cogent Communications, Inc.	United States	Before monitoring	2026-11-01 22:23	Announcing
38.236.128.0/19	AS52772	Sjnet Telecom	Brazil	Before monitoring	2026-10-31 08:19	Stopped
38.0.0.0/8	AS174	Cogent Communications, Inc.	United States	Before monitoring	2026-11-01 22:23	Announcing

More specific routes18 total

Prefix	ASN	Name	Registered country	First seen (UTC)	Last seen (UTC)	Status
38.236.128.0/24	AS174	Cogent Communications, Inc.	United States	Before monitoring	2026-11-01 22:23	Announcing
38.236.129.0/24	AS174	Cogent Communications, Inc.	United States	Before monitoring	2026-11-01 22:23	Announcing
38.236.130.0/24	AS174	Cogent Communications, Inc.	United States	Before monitoring	2026-11-01 22:23	Announcing
38.236.131.0/24	AS174	Cogent Communications, Inc.	United States	Before monitoring	2026-11-01 22:23	Announcing
38.236.132.0/24	AS174	Cogent Communications, Inc.	United States	Before monitoring	2026-11-01 22:23	Announcing
38.236.133.0/24	AS174	Cogent Communications, Inc.	United States	Before monitoring	2026-11-01 22:23	Announcing
38.236.134.0/24	AS174	Cogent Communications, Inc.	United States	Before monitoring	2026-11-01 22:23	Announcing
38.236.135.0/24	AS174	Cogent Communications, Inc.	United States	Before monitoring	2026-11-01 22:23	Announcing
38.236.136.0/24	AS174	Cogent Communications, Inc.	United States	Before monitoring	2026-11-01 22:23	Announcing
38.236.137.0/24	AS174	Cogent Communications, Inc.	United States	Before monitoring	2026-11-01 22:23	Announcing
38.236.138.0/24	AS174	Cogent Communications, Inc.	United States	Before monitoring	2026-11-01 22:23	Announcing
38.236.139.0/24	AS174	Cogent Communications, Inc.	United States	Before monitoring	2026-11-01 22:23	Announcing
38.236.140.0/24	AS174	Cogent Communications, Inc.	United States	Before monitoring	2026-11-01 22:23	Announcing
38.236.141.0/24	AS174	Cogent Communications, Inc.	United States	Before monitoring	2026-11-01 22:23	Announcing
38.236.142.0/24	AS174	Cogent Communications, Inc.	United States	Before monitoring	2026-11-01 22:23	Announcing
38.236.143.0/24	AS174	Cogent Communications, Inc.	United States	Before monitoring	2026-11-01 22:23	Announcing
38.236.128.0/21	AS52772	Sjnet Telecom	Brazil	Before monitoring	2026-10-30 00:19	Stopped
38.236.136.0/21	AS52772	Sjnet Telecom	Brazil	Before monitoring	2026-10-30 00:19	Stopped

Change logAll changes

Detected (UTC)	Prefix	Change	ASN	Name	Previous ASN	Country
2026-10-30 02:20	38.236.128.0/20	Withdrawal	AS52772	Sjnet Telecom	—	Brazil

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RIR allocation record

Registry: ARIN
Allocated block: 38.0.0.0/8
Country: United States
Allocation date: 1991-04-16
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.