# `ASN_NOT_FOUND` (HTTP 404): no autonomous system with that number is in the index

GET /api/v1/ip/asn/{asn} found nothing to report: the ASN database assigns no prefix to that number. Nothing is charged.

The ASN endpoint reads an index built from the DB-IP ASN database: every autonomous system that database assigns at least one prefix to. A number that announces nothing the database knows — a reserved or private number, a system that has never held address space, a typo — is not in it.

It is a fact about the database, not about the registry: the RIR statistics may well have allocated the number. Looking up an address is unaffected; an address answers its own asn and org from the same database.

**What to do.** Check the number, or look up an address inside the network you mean and read the asn the answer carries.

```json
{
    "success": false,
    "error": {
        "code": "ASN_NOT_FOUND",
        "message": "No autonomous system numbered 999999 is in the index.",
        "request_id": "req_01m1kgdm4xngzmbmff68g94w0c"
    }
}
```

Reference: https://spaw.co/docs/errors/ASN_NOT_FOUND