Register a new account in Cloudflare or enter the credentials of the existing one:
Enter the account Email.
Enter the account Password.
Click on Ok.
Go to Tools → Cloudflare → select the domain you want to connect → Add.
You can connect only second-level domains to Cloudflare.
Select the Connection type:
Full connection — a domain zone will be connected to Cloudflare in full;
Partial connection — only some pages from a domain zone will be connected to Cloudflare. Enter the CNAME record for Cloudflare that will point to one of the IP addresses of the domain zone you want to connect. Enter all Aliases of the WWW-domain name, separated by space. By default, it includes all the aliases created in ISPmanager.
Click on Ok.
In Tools → Cloudflare → the column Status the domain status will change to "Connection to Cloudflare in progress". This process may take several minutes. The information about domain statuses is updated automatically once in half-an-hour. Click the Update button to update it manually. Status change history is saved in the event Log. On the last step, you will see the message in the log "To complete the integration with Cloudflare change the NS records of the domain zone" where the Cloudflare NS servers will be located. Specify them in the NS-records of the domain zone registrar.
You can check NS-records using the dig utility. Cloudflare NS-servers must be displayed after you have executed the command:
dig NS <domain zone> +short
After the information has been updated, the connection will change to "Domain is connected to Cloudflare". The Cloudflare functions will become available for the domain. Initial settings will be sent to Cloudflare automatically depending on domain and server configuration: