# SVCB

`SVCB` adds a [Service Binding record](https://www.rfc-editor.org/rfc/rfc9460) to a domain. The name should be the relative label for the record. Use `@` for the domain apex.

The priority must be a positive number, the address should be an ip address, either a string, or a numeric value obtained via [IP](https://docs.dnscontrol.org/language-reference/top-level-functions/ip).

The params may be configured to specify the `alpn`, `ipv4hint`, `ipv6hint`, `ech` or `port` setting. Several params may be joined by a space. Not existing params may be specified as an empty string `""`

Modifiers can be any number of [record modifiers](https://docs.dnscontrol.org/language-reference/record-modifiers) or JSON objects, which will be merged into the record's metadata.

{% code title="dnsconfig.js" %}

```javascript
D("example.com", REG_MY_PROVIDER, DnsProvider(DSP_MY_PROVIDER),
  SVCB("@", 1, ".", "ipv4hint=123.123.123.123 alpn=h3,h2 port=443"),
);
```

{% endcode %}