cPanel and WHM logins will transmit the sensitive username and password through the internet and it need to be secure. If anyone intercepts the traffic, they will be able to decode the username and password if they are submitted in a insecure page. Hence it is quite vital to use secure pages for WHM, cPanel and Webmail logins.
Recent versions of cPanel allow administrators the option of hosting a MySQL server on a separate box, which can help decrease resource usage from high-activity MySQL databases. Setting up the remote database server is easy.
cPanel offer two FTP servers to choose with. PureFTP and ProFTP - the default one is pure FTP. If you want to make a change, you can do this from WHM Main >> Service Configuration >> FTP Server Selection.
A DNS cluster is a set of DNS servers that share and synchronize DNS zone files. Having a nameserver cluster will help your domain to be online even if one of your DNS servers goes down.
cPanel is designed to host multiple domains in a single server. And because the IPv4 is a scarce resource, cPanel is designed in a way that it will rather use same IP for multiple domains. Such an IP is called a "shared IP address".