Yes, managing A records for subdomains be done using the API. I set up a similar setup for a project of mine not long ago. Here is what I did.

• I pointed my domain to ns1/3.digitalocean.com
• Via the control panel I added my domain in the DNS section and pointed the main domain and the www subdomain to my main droplet.
• When a new user signed up my system would create a new droplet on my account for them and then use the API to create a subdomain record pointing to their new IP.
• The API can then be used to either delete and recreate the subdomain or edit it.

This will allow the user to change their A record to point to any IP address.

Currently our DNS system does not support subdomain NS records so using this method would not allow your users to set up NS records to delegate their subdomain to another DNS server. If that is a requirement you would have to look into setting up nameservers using BIND or another DNS server and write the code to modify those records.

Documentation on managing records within a domain via the API.

I done it! Just what I wanted. Maybe this will be useful for someone, I was coding quickly, without any validations and so this more like an example, but it's working, here is how I done it.

First of all, I use Laravel 5. But this will work for anyone who has Guzzle 4.0+ (doesn't work on 6.0+).

In controller.

```use GuzzleHttp\Client;

public function addDomain(){

    $digitalOcean = new Client([
        'base_url' => 'https://api.digitalocean.com/v2/',
        'defaults' => [
            'auth' => [
                'YOUR_API_TOKEN_HERE',
                ':'
            ]
        ]
    ]);

    $request = $digitalOcean->post('domains', [
        'json' => [
            'name' => 'example.domain.com',
            'ip_address' => '123.123.123.123'
        ]
    ]);

    $domain = $request->json();

    dd($domain); // just to see result.
}

Digital Ocean is BEST!! <3