WordPress support documents state that you are required to add a wildcard entry for Apache in the httpd.conf as well as in your DNS zone to use WordPress MultiSite on subdomains. On a cPanel server this process is extremely simple as you can accomplish this in only a few simple steps.
- Log into your cPanel account.
- Click on "Subdomains" under the "Domains" group.
- Enter a single "*" into the subdomain line and choose which domain you wish to add the wildcard to in the drop-down box. (Demonstration Image)
- Enter the directory where WordPress Multisite is installed into "Document Root".
- Click "Create"