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+## DNS and subdomains for the applications
+
+### Subdomains
+
+YunoHost allows the use of subdomains. If one owns a domain name `mydomain.com`, one first needs to create the subdomains in the DNS configuration (with one's registrar like Gandi).
+
+### Configuration example with Gandi
+
+The DNS configuration needs an A record with an IPv4 address, an AAAA record with an IPv6 address, and various CNAME records, one for each desired subdomain.
+
+If your DNS configuration looks like:
+```bash
+@         A            XYZ.XYZ.XYZ.XYZ
+@         AAAA         1234:1234:1234:FFAA:FFAA:FFAA:FFAA:AAFF
+*         CNAME        mydomain.com.
+agenda    CNAME        mydomain.com.
+blog      CNAME        mydomain.com.
+rss       CNAME        mydomain.com.
+```
+then you can access `agenda.mydomain.com`, `blog.mydomain.com` and `rss.mydomain.com` subdomains.
+
+### Install an application on a subdomain
+
+To install an application on a subdomain in YunoHost, for example `blog.mydomain.com`, the configuration is done in the administration panel. One first add the subdomain to the available domains list. The creation of a subdomain in Yunohost will create the corresponding configuration files  for Nginx (the web server used in YunoHost).
+
+Then, in the applications>install panel, one follows the classic installation process by choosing the desired subdomain as domain (for example `blog.mydomain.com`). One needs to choose the path `/` (in place of `/wordpress` for example). A warning message will appear telling that it won't be possible to install other application to this subdomain. After validation, the installation starts.
+
+The application is then available at `blog.mydomain.com` (and not `mydomain.com/wordpress`).
+
+### Moving an application to a subdomain
+
+What happens if the application is already installed? For example, one wants to move `mydomain.com/wordpress` to `blog.mydomain.com`.
+It depends on the application. 
+Some applications allow the change of domain. In that case, one can proceed to the change through the administration panel Applications>the_app>change URL. 
+If the application doesn't allow URL change, then there is no easy way to do it. The best solution is to reinstall the application.
+
+### Reinstalling an application
+
+First, save the application data through the backup process. Then uninstall the application with the administration panel. Then reinstall the application to the desired domain. Finally, restore the backup.