Dns question adding a local server

Hi all,
I have a server hosted locally on my network - the same network as my miab server.
I have letsencrypt setup and its working ok on my miab server.
I would like this server to able to use the same letsencrypt certs for the domain.
Currently I have box.jbsmith.org I want to add next.jsbmith.org to the dns and point to a local address

should I use the following command to add the dns entry. How do I specify the local lan address for server
curl -X PUT https://box.jbsmith.org/admin/dns/custom/next.jbsmith.org