Let’s Encrypt client domain name

Hello,
on a Windows server 2012R2 I have installed an Ubuntu 16.04 LTS virtual maschine (Hyper-V) with apache web server and nextcloud 13.

My internet provider gives me a dynamic IP what change sometimes. To reach my computer I have an account at DynDNS.org. With EDDFComputer.dyndns.org I can reach my internet IP. I opened port 443 in my router and forward the port to the ubuntu computer.

Now I updated apache server to get a connection via HTTPS. To get a certificate from Let`s Encrypt I have to execute

certbot --authenticator standalone --installer apache -d cloud.firma.com --pre-hook “service apache2 stop” --post-hook “service apache2 start”

My question is now what domain name I have to write in the command? -d and an extra domain name (where do i get the name from? ) or -d EDDFComputer.dyndns.org ?

Wolfgang

You put the domain name that you want to use to reach your nextcloud, in your example:
EDDFComputer.dyndns.org

cloud.firma.com is a different host name you use on your webserver? You can make the same certificate work for different hostnames (e.g. if you want to reach your cloud via cloud.firma.com, or if you have a website www.firma.com).