> ## Documentation Index
> Fetch the complete documentation index at: https://docs.roundproxies.com/llms.txt
> Use this file to discover all available pages before exploring further.

# ASN-Targeting

> Route residential traffic through a specific Autonomous System Number (ASN).

ASN-targeting routes requests through residential IPs that belong to a specific Autonomous System — typically a single ISP or carrier. This is useful when a target site treats traffic differently based on the network operator (for example, mobile carriers vs. consumer broadband ISPs).

<Note>
  ASNs are 32-bit identifiers assigned by IANA/RIRs to networks that announce routes on the public internet. Each major ISP, mobile carrier, and hosting provider has one or more ASNs.
</Note>

## Targeting Format

Add the `asn` parameter to your proxy username:

```
client-{CLIENT_ID}-asn-{ASN_NUMBER}-session-{SESSION_ID}
```

<ResponseField name="asn" type="string" required="false">
  Numeric ASN of the network you want to route through. Use the number only — do not include the `AS` prefix.
</ResponseField>

| Parameter | Description                             | Example    |
| --------- | --------------------------------------- | ---------- |
| `asn`     | Numeric ASN identifier (no `AS` prefix) | `asn-3320` |

## Combining With Geo-Targeting

ASN-targeting can be combined with `country` to narrow the pool to IPs from a specific ISP within a single country:

```
client-{CLIENT_ID}-country-Germany-asn-3320-session-{SESSION_ID}
```

State and city can be added on top, but the available IP pool shrinks quickly — start broad and refine only if needed.

## Example Request

<CodeGroup>
  ```python Python theme={null}
  import requests

  proxies = {
      'http': 'http://client-{CLIENT_ID}-country-Germany-asn-3320-session-fnzwtath:{PASSWORD}@residential.roundproxies.com:5000',
      'https': 'http://client-{CLIENT_ID}-country-Germany-asn-3320-session-fnzwtath:{PASSWORD}@residential.roundproxies.com:5000'
  }

  response = requests.get('https://api.ipify.org?format=json', proxies=proxies)
  print(response.json())
  ```

  ```bash cURL theme={null}
  curl -x "http://client-{CLIENT_ID}-country-Germany-asn-3320-session-fnzwtath:{PASSWORD}@residential.roundproxies.com:5000" \
    https://api.ipify.org?format=json
  ```
</CodeGroup>

## Finding an ASN

You can look up the ASN of any IP or ISP using public tools:

* [bgp.he.net](https://bgp.he.net) — search by ISP name or IP
* [ipinfo.io](https://ipinfo.io) — returns ASN alongside IP metadata
* `whois <ip>` from the command line

Common examples:

| ISP                          | ASN    |
| ---------------------------- | ------ |
| Deutsche Telekom (Germany)   | `3320` |
| Comcast (US)                 | `7922` |
| Vodafone (UK)                | `5378` |
| Bezeq International (Israel) | `8551` |

## Troubleshooting

* **`No Available IPs for Targeting`** — the requested ASN has no live IPs at the moment, or it doesn't intersect with your `country`/`state` constraints. Drop the geo refinements or try a related ASN from the same carrier.
* **`Invalid Targeting Parameter`** — ensure the ASN is numeric only (e.g. `asn-3320`, not `asn-AS3320`).
* See [Error Handling](/residentials/error-handling) for the full list of proxy errors.