# DNS and Routing
source: https://docs.chalk.ai/docs/scaling-groups/dns-and-routing

## Find a scaling group's DNS hostname and send requests to it from the SDK.

Every scaling group is automatically assigned a TLS-terminated DNS hostname
through the cluster's gateway. The pattern is:

```
<environment-id>-<scaling-group-name>.<gateway-domain>
```

For example, a scaling group named inference in environment abc123 with
gateway domain gw.chalk.ai would be reachable at:

```
https://abc123-inference.gw.chalk.ai
```

In the SDK examples on this page, sg is a deployed group, such as the one from
the Quick start. From the SDK, read
the hostname off the deployed group:

```
print(sg.web_url)
# https://abc123-inference.gw.chalk.ai
```

From the CLI, the URL is shown as Web URL in the output of chalk scaling-group get and chalk scaling-group list. Traffic arriving at this
hostname is routed to the port you specified with --port (or the port
constructor argument).

Because the hostname includes the scaling group name, you can reference it by
a stable, human-readable URL rather than an opaque UUID.

To require a Chalk access token on requests to this hostname, see
Authentication.

### Invoking from the SDK

The .call() helper sends a request to a path under web_url. The response it
returns has status, headers, and content attributes, plus text() and
json() methods. Use .call() for ad-hoc requests from the SDK, and send
production traffic to web_url directly.

This example sends JSON to /predict, which stands for a route your own
service serves:

```
resp = sg.call(
    "/predict",
    method="POST",
    json={"text": "the cat sat on the mat"},
    timeout=60.0,
)
print(resp.json())
```