How to Access the Apache Configuration Files on Your web Server
Adding a wildcard host to your WordPress web server requires that you access the Apache configuration files on your web server. These steps assume that you have access to those files; if you do not, ask your web hosting provider either to provide you with the access you need or to complete the steps for you to add the wildcard host to your account.
Here’s how you set this feature up:
Log in to your website with the root user via a terminal and navigate to the configuration files in the folder located at /etc/httpd/ by typing cd /etc/httpd/.
Open the httpd.conf file by typing vi httpd.conf.
Page down in the file until you see the vhost section. Find the vhost section that contains the information about your WordPress installation and the main domain of your network. (Depending on the number of domains hosted on your server, there may be several vhost entries in the httpd.conf file — be sure that you’re editing the vhost that contains the main domain of your WordPress install.)
Press the Insert key to begin editing the file.
Comment out the lines and place the wildcard as shown: <VirtualHost *:80>
Save the changes by pressing the Esc key, typing :wq, and then pressing Enter.
On the command line, restart Apache by typing /etc/init.d/apache restart.
Log in to your domain name registrar.
Click the domain name management tools for the domain you want to map.
Click the Total DNS records.
Locate the A records at the top of the page.
Insert the IP address of your WordPress network.
The figure shows an A record and the web server’s IP address it points to. The domain is sent to that IP address regardless of nameserver.
Choose Network Admin→Domains from your WordPress Dashboard.
The Domain Mapping: Domains page appears.
Enter the ID of the site you want to map.
You can get the ID number from the Sites page (Super Admin→Sites).
Enter the domain name you want to map to this site.
Click Save. The page refreshes and shows you a list of mapped domains.
There is no longer any need to park or point domains at the web host. The server is instructed to take any domain name request and send it to the WordPress network. WordPress associates the mapped domain with the correct site.