Frequently asked questions
Results and output
What date/time format does Cache-Date represent?
Cache-Date is the number of seconds since the Epoch at the moment the responding server's route cache was last updated. Most systems with the date utility can type date -r <seconds> to convert it. Alternatively, switch to type=rpsl for the RPSL-compliant date format, which carries day precision only.
Are key:value pairs guaranteed to appear in the same order?
No. Order is not guaranteed from query to query — servers differ in version and data set, and fields will be added. Parsers should match on the key, not the line offset.
Why does Prefix WhoIs give a different AS than ARIN or RIPE whois?
Because they answer different questions. The registry says who holds the allocation; we say who is announcing it in BGP right now. When they differ, the route is what is carrying traffic. Ask for a combined query to see both.
Why is the AS-Path different from what my router sees?
Because it is the path from our peers. AS paths are inherently relative to the observer. If you need your own perspective, run your own pWhoIs server fed from your routers.
How fresh is the data?
Each node refreshes its table on a schedule and reports the refresh time as Cache-Date. Type version on port 43 to see the current cache time and prefix and peer counts for the node that answered you.
Asking
How do I get JSON?
jsonp pretty-prints; json-all and jsonp-all return the extended field set.
How do I look up many addresses at once?
Send begin, one address per line, then end — through netcat, WhoB, or the C and PHP libraries. Only the native and Cymru output types support bulk.
How do I see every prefix an AS announces?
For everything that transits an AS: routeview transit-as=3356. For all active routes covering a prefix: routeview prefix=4.0.0.0/8.
Does it support IPv6?
Yes. The public server caches a quarter-million IPv6 prefixes alongside over a million IPv4 prefixes; the exact live counts are in the status rail at the top of this page when the service is answering.
Is there Cymru-compatible output?
Yes: type=cymru. Also type=rpsl for RFC 2622 format.
Limits
I got rate-limited. Now what?
Switch to bulk mode and cache results for at least the Cache-Date interval. If you still need more than a few thousand queries a day, use the request form and include the static addresses you query from. Higher limits are customarily granted free upon reasonable request for education, research and government use.
Can I redistribute the data commercially?
That needs a conversation first — get in touch.