101.4.0.0/20

Currently announced by AS4538 CERNET-CN, in the routed prefix 101.4.0.0/20.

Routing data · Nov 8, 2026, 10:26 UTC

ASN historyEvery routed prefix covering 101.4.0.0/20

Prefix	ASN	Name	Registered country	First seen (UTC)	Last seen (UTC)	Status
101.4.0.0/20	AS4538	CERNET-CN	China	Before monitoring	2026-11-08 10:26	Announcing
101.4.0.0/14	AS4538	CERNET-CN	China	Before monitoring	2026-11-08 10:26	Announcing

Prefix	ASN	Name	Registered country	First seen (UTC)	Last seen (UTC)	Status
101.4.2.0/24	AS4538	CERNET-CN	China	Before monitoring	2026-11-08 10:26	Announcing

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

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.