How to Clone WordPress Network Subdomains

1. Create the new subdomain using your Web hosting provider's instructions. A subdomain usually follows the 'subdomain.primarydomain.com' format, in which 'primarydomain.com' is your existing domain.
2. Back up your entire WordPress installation to your computer's hard drive using FTP, and back up your WordPress database using phpMyAdmin or a WordPress database backup plug-in. Place them into a folder named 'Old Site.'

3. Install the Maintenance Mode plug-in into your existing WordPress installation and activate it. This will prevent visitors from entering your site while you're working.
4. Go to the WordPress administration area of your existing site, click 'General' in the 'Settings' submenu and change both the 'WordPress Address' and 'Site Address' to the new URL including the subdomain. Click 'Save Changes.'
5. Download a new copy of your WordPress installation to your computer's hard drive and create a new backup of your database. Don't overwrite the copies you created in Step 2. Place them into a folder named 'New Site.'
6. Create a new SQL database for your new WordPress clone using the instructions from your Web hosting provider and restore the database backup from your 'New Site' folder.
7. Open the 'wp-config.php' file in your 'New Site' folder in a text editor and edit the database name, user name and any other details that have changed.
8. Copy the WordPress installation from your 'New Site' folder to the subdomain. Log in to the new site's administration area and deactivate the Maintenance Mode plug-in. Your subdomain clone is now live.
9. Delete your old site's database and then restore it from the copy in your 'Old Site' folder. Copy the WordPress installation from your 'Old Site' folder to your original site's domain, overwriting the existing files. You should now have two functional copies of your site, one at the primary domain URL and one at the subdomain.