i'm trying to use dynu to point my ip address (numeric) to a hotname, how i can do that?

You may sign up for dynamic DNS service for your domain name and run our client software to keep your domain name mapped to your current IP address. If you have a top level domain name like yourdomain.com, you need to list our name servers for your domain name:

NS1.DYNU.COM
NS2.DYNU.COM
NS3.DYNU.COM
NS4.DYNU.COM
NS5.DYNU.COM

For more information, you may refer to https://www.dynu.com/Resources/Tutorials/DynamicDNS/GettingStarted