Route monitor

Every 2 hours ASNBase compares the global BGP routing table to find IP prefixes whose origin ASN changed: moved to another ASN, announced for the first time, gained an extra origin, or withdrawn from the table.

Origin change: 99; Last 24 hours
New announcement: 723; Last 24 hours
Origin added: 28; Last 24 hours
Withdrawal: 1,780; Last 24 hours

Routing data · Oct 26, 2026, 22:20 UTC

Prefixes with a new ASNClear filters

CountryIP versionASN

No matching changes.

By day

Origin change
New announcement
Origin added

Prefixes with a new ASN on each of the last 7 days, excluding withdrawals. Select a date to see all of that day’s changes. Another 1,008 changes are waiting for confirmation at the next comparison.

IP address ASN history

Enter an IP address or prefix to see which ASNs have announced the routes covering it.

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.