Android Question Obtain in B4A the IP address of a domain

What do you need it for?
Socket.ResolveHost will do it however it is deprecated as it does it on the main thread and will only work if you disable the network on main thread check.
In most cases it is not needed as the host will be resolved automatically.

I mean , in the jrdc2 client to use remote internet server connection using an dynamic IP , and the service of no-ip,dyndns, etc???

You don't need it and it will not help in any way.

The host will be resolved internally.