BGP Prefix Lookup

On the internet, routes are announced as prefixes: an autonomous system tells its neighbours via BGP that it can deliver traffic for, say, 62.103.0.0/16. This tool looks a prefix up in our daily copy of the global routing table and shows three things:

• Exact announcements: which AS originates exactly this prefix. More than one origin (a MOAS) is normal for anycast services and some multihomed networks, and suspicious otherwise.
• Covering routes: less-specific announcements that contain it. Traffic follows the most specific route, so a covering route matters if the more-specific one disappears.
• More-specifics: announcements inside it, which may belong to other networks (customers, or a hijack).

Each announced route is also checked against the RPKI: whether a ROA authorises its origin AS.

The table is the view from APNIC’s route collector. Most of the global table is the same from everywhere, but a route that is filtered before it reaches that collector will not appear.