rewrite rule for any subdomain to main domain - apache

Question

I have a site called mailcake.com, and I would like to have beta.mailcake.com, to redirect to mailcake.com, How can I achieve this? I have it like this on /etc/httpd/conf.d/mailcake.conf
NameVirtualHost *:443
<VirtualHost *:80>
DocumentRoot /var/www/mailcake
ServerName mailcake.com
ServerAlias www.mailcake.com beta.mailcake.com
RewriteEngine On
RewriteCond %{HTTP_HOST} ^beta\.mailcake\.com$ [NC]
RewriteRule (.+)$ "http://mailcake.com" [L,P]
ErrorLog /var/log/mailcake.com-error_log
<Directory />
Options Indexes FollowSymLinks
AllowOverride All
</Directory>
</VirtualHost>
<VirtualHost *:443>
DocumentRoot /var/www/mailcake
ServerName mailcake.com
ServerAlias www.mailcake.com
SSLEngine on
SSLCertificateFile /var/www/mailcake.crt
SSLCertificateKeyFile /var/www/mailcake.key
ErrorLog /var/log/mailcake.com-error_log
<Directory />
Options Indexes FollowSymLinks
AllowOverride All
</Directory>
</VirtualHost>
but it does not work

Answer 1

The following seems to work when tested with a few URLs:
RewriteCond %{HTTP_HOST} ^(beta\.)?mailcake\.com
RewriteRule (.*) http://mailcake.com/$1 [QSA]
Part of the important bit here is adding the $1 to ensure that any paths get added to the URL (in your example, http://beta.mailcake.com/stats/ would get redirected to http://mailcake.com/, which possibly isn't desireable. Also, adding [QSA] should ensure any query strings are passed along too.
If you're doing the redirect within the httpd.conf, I probably also wouldn't add [L], as it could stop other valid redirects within any .htaccess files from working.