How can I enable route optimization for a model serving endpoint in Databricks, and what are the limitations of using this feature?
To enable route optimization for a model serving endpoint in Databricks, you can specify the `route_optimized` parameter during model serving endpoint creation. Here's an example request using Python:

```python
POST /api/2.0/serving-endpoints {
  "name": "my-endpoint",
  "config": {
    "served_entities": [{
      "entity_name": "ads1",
      "entity_version": "1",
      "workload_type": "CPU",
      "workload_size": "Small",
      "scale_to_zero_enabled": true,
    }],
  },
  "route_optimized": true
}
```

However, there are some limitations to using this feature:

1. OAuth tokens are the only supported authentication for route optimization. Personal access tokens are not supported.
2. Route optimization does not enforce any network restrictions you might have configured in your Databricks workspace such as IP access control lists or PrivateLink. Do not enable route optimization if you require that model serving traffic be bound by those controls. If you have such network requirements and still want to try route-optimized model serving, reach out to your Databricks account team.