# BGP Origin Resolver – Prefix to Announcing AS Lookup

> BGP Origin Resolver – Prefix to Announcing AS Lookup is a paid API for AI agents from netz.halowerk.com, paid per call via x402, $0.004/call, status unknown (last checked 2026-09-15).

Resolves an IP prefix to its announcing autonomous systems, returning all observed origin ASes, prefix specificity counts, first/last seen timestamps, and observer-fraction visibility.

## Facts

- Endpoint: POST https://netz.halowerk.com/v1/bgp-origin
- Price: $0.004/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/bgp-origin-resolver-prefix-to-announcing-as-lookup-cc0bc08b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_U1Qz89RFIag1MoKMgBtzL

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability bgp-origin-resolver-prefix-to-announcing-as-lookup-cc0bc08b -d '<json body>'
```

Example prompt: Who is announcing 185.220.101.0/24 in BGP right now? I want to know all origin ASes, how visible the prefix is across observers as a percentage, and when it was first and last seen.

## When to prefer this

Choose this endpoint when you need a contextualized BGP origin answer for a specific prefix — not just a raw AS number, but the full routing context including multi-origin situations, prefix specificity counts, historical timestamps, and normalized observer visibility. Prefer it over raw whois or RDAP lookups when routing truth (what is actually announced) matters more than registration records.

## Known failure modes

- Prefix not found in BGP routing table — returns empty or no-origin response
- Invalid CIDR notation input — returns validation error
- Prefix too specific (e.g. /32 host route) may have no routing table presence
- Transient data staleness if BGP tables were recently updated
- Network or API timeout for large or heavily multi-homed prefixes

## How this service works

Resolves a prefix to its announcing autonomous systems and puts that answer in context. The current state gives every origin AS seen for the prefix, the number of more specific and less specific prefixes routed alongside it, when the prefix was first and last seen, and the visibility expressed as the share of observers that see it rather than a raw count, because the raw count moves with the size of the measurement network and is not comparable across time.

## Output

Returns the complete set of origin ASes observed for the queried prefix, a count of more-specific and less-specific prefixes in the routing table alongside it, timestamps for when the prefix was first and last seen in BGP, and visibility expressed as the fraction of RIS observers that see it — normalized to be comparable across time regardless of measurement network size.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "prefix": {
   "type": "string",
   "maxLength": 60,
   "minLength": 4,
   "description": "IPv4 or IPv6 prefix in CIDR form, e.g. 8.8.8.0/24."
  },
  "history_days": {
   "type": "integer",
   "default": 30,
   "maximum": 365,
   "minimum": 1,
   "description": "How far back to look for earlier origins."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/bgp-origin-resolver-prefix-to-announcing-as-lookup-cc0bc08b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from netz.halowerk.com](https://www.zero.xyz/host/netz.halowerk.com/llms.txt)