asn.dev

Observed topology

AS1921 RCODEZERO-ANYCAST-SEC1-TLD RcodeZero Anycast DNS

Hosting RIPE

Upstreams 39 carry this network
Downstreams 1 this network carries
Adjacent (IPv4) 37
Adjacent (IPv6) 25
Upstream graph Who carries AS1921, and who carries them, drawn as a map up to the transit-free core. 11 exchanges Where AS1921 physically turns up to peer, and its address on each fabric.

Transit

Upstream networks

All 39

Networks observed carrying traffic for AS1921: the AS immediately before it in a routing path. Ranked by how many paths showed the relationship, which reflects how widely it is used, not how much traffic crosses it.

ASNetworkTypeFamiliesPaths seen
AS20473The Constant Company, LLCHostingIPv4 IPv6409
AS56655Gigahost ASUnclassifiedIPv4 IPv6132
AS44066firstcolo GmbHUnclassifiedIPv4 IPv649
AS6939Hurricane Electric LLCTransitIPv4 IPv638
AS199524G-Core Labs S.A.HostingIPv435
AS8849Melbikomas UABHostingIPv4 IPv633
AS42708Glesys ABUnclassifiedIPv4 IPv632
AS5459London Internet Exchange Ltd.UnclassifiedIPv430
AS56630Melbikomas UABHostingIPv4 IPv627
AS29014ScaleUp Technologies GmbH & Co. KGHostingIPv426

All 39 upstreams →

Transit

Downstream networks

inferred

Networks for which AS1921 was observed as the last hop before the origin, meaning it appears to provide them transit.

ASNetworkTypeFamiliesPaths seen
AS35052ACONETUnclassifiedIPv4 IPv649

Adjacency

Adjacent networks

All 41

Every AS seen directly next to AS1921 in a routing path, in either direction.

ASNetworkTypeFamiliesPaths seen
AS20473The Constant Company, LLCHostingIPv4 IPv6409
AS56655Gigahost ASUnclassifiedIPv4 IPv6132
AS6939Hurricane Electric LLCTransitIPv4 IPv668
AS35052ACONETUnclassifiedIPv4 IPv649
AS44066firstcolo GmbHUnclassifiedIPv4 IPv649
AS199524G-Core Labs S.A.HostingIPv435
AS5459London Internet Exchange Ltd.UnclassifiedIPv434
AS8849Melbikomas UABHostingIPv4 IPv633
AS42708Glesys ABUnclassifiedIPv4 IPv632
AS56630Melbikomas UABHostingIPv4 IPv627

All 41 adjacent →

Provenance

Where this comes from

Derived from routing tables collected at 2026-10-14 10:00 UTC by route-views2,rrc00, as seen from 75 BGP vantage points across 73.25M route entries. These are observations from those vantage points, not a complete or authoritative view of the internet.

Inferred from path position, not from any declaration by either party. A network appearing here is carrying these routes; whether that is a paid transit arrangement, a backup, or something else is not something routing data can tell you. Adjacency is not the same as peering. Being next to each other in a path covers paid transit, settlement-free peering and customer connections alike, and routing data cannot distinguish them. Treat this as "these networks exchange routes", nothing more specific.

Cross-check against RIPEstat or BGP.tools, which observe from a different and larger set of vantage points.