Yes, you can add a Custom Sub Domain, 

How to point your custom sub-domain name to our IP ( Linko )?

To point your custom sub-domain name on our platform, 

1. Go to your ⇾ DNS zone,
2. Create an "A" record,
3. Set Host to your desired name, For example: "go, link, out ", and
4. Set the value to our IP - 45.77.172.5

Your final custom sub-domain will look like this ⇾ link.domain.com pointed to our server.