66.166.128.0/20

Currently announced by AS22773 Cox Communications, in the routed prefix 66.166.128.0/20.

Current ASN: AS22773; Cox Communications
Routed prefix: 66.166.128.0/20; Most specific route covering this prefix
ASNs over time: 2; 2 announcement records
RIR allocation: ARIN; United States · 66.166.0.0/15

Routing data · Nov 2, 2026, 00:27 UTC

ASN historyEvery routed prefix covering 66.166.128.0/20

Prefix	ASN	Name	Registered country	First seen (UTC)	Last seen (UTC)	Status
66.166.128.0/20	AS22773	Cox Communications	United States	2026-10-30 18:22	2026-11-02 00:27	Announcing
66.166.0.0/15	AS3257	GTT Communications (AS3257)	United States	Before monitoring	2026-11-02 00:27	Announcing

More specific routes16 total

Prefix	ASN	Name	Registered country	First seen (UTC)	Last seen (UTC)	Status
66.166.128.0/24	AS22773	Cox Communications	United States	Before monitoring	2026-11-02 00:27	Announcing
66.166.129.0/24	AS22773	Cox Communications	United States	Before monitoring	2026-11-02 00:27	Announcing
66.166.130.0/24	AS22773	Cox Communications	United States	Before monitoring	2026-11-02 00:27	Announcing
66.166.131.0/24	AS22773	Cox Communications	United States	Before monitoring	2026-11-02 00:27	Announcing
66.166.132.0/24	AS22773	Cox Communications	United States	Before monitoring	2026-11-02 00:27	Announcing
66.166.133.0/24	AS22773	Cox Communications	United States	Before monitoring	2026-11-02 00:27	Announcing
66.166.134.0/24	AS22773	Cox Communications	United States	Before monitoring	2026-11-02 00:27	Announcing
66.166.135.0/24	AS22773	Cox Communications	United States	Before monitoring	2026-11-02 00:27	Announcing
66.166.136.0/24	AS22773	Cox Communications	United States	Before monitoring	2026-11-02 00:27	Announcing
66.166.137.0/24	AS22773	Cox Communications	United States	Before monitoring	2026-11-02 00:27	Announcing
66.166.138.0/24	AS22773	Cox Communications	United States	Before monitoring	2026-11-02 00:27	Announcing
66.166.139.0/24	AS22773	Cox Communications	United States	Before monitoring	2026-11-02 00:27	Announcing
66.166.140.0/24	AS22773	Cox Communications	United States	Before monitoring	2026-11-02 00:27	Announcing
66.166.141.0/24	AS22773	Cox Communications	United States	Before monitoring	2026-11-02 00:27	Announcing
66.166.142.0/24	AS22773	Cox Communications	United States	Before monitoring	2026-11-02 00:27	Announcing
66.166.143.0/24	AS22773	Cox Communications	United States	Before monitoring	2026-11-02 00:27	Announcing

Change logAll changes

Detected (UTC)	Prefix	Change	ASN	Name	Previous ASN	Country
2026-10-30 18:22	66.166.128.0/20	New announcement	AS22773	Cox Communications	—	United States

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RIR allocation record

Registry: ARIN
Allocated block: 66.166.0.0/15
Country: United States
Allocation date: 2001-09-10
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.