In some situations, you may want to have domain.com as well as *.domain.com point to the same site in Plesk. Plesk will automatically set up hosting for domain.com and www.domain.com within the Apache configuration, but you can direct all subdomains for a particular domain to a certain virtual host fairly easily.
DNS Configuration:
Add a CNAME or A record for *.domain.com which points to domain.com (for a CNAME), or the domain’s IP (for an A record).
vi /var/named/run-root/var/domain.com
Add the following line,
*.domain.com. IN CNAME domain.com.
OR
*.domain.com. IN A 12.34.56.78(A Record IP of the domain)
Restart the DNS service
/etc/init.d/named restart
Apache Configuration:
Edit the /var/www/vhosts/domain.com/conf/vhost.conf or create the vhost.conf if doesn’t exist and add the following line,
ServerAlias *.domain.com
then Run,
/usr/local/psa/admin/bin/websrvmng -av
Add the following line in /var/www/vhosts/domain.com/conf/httpd.include file,(With in 80,443 VirtualHost entries)
Include /var/www/vhosts/domain.com/conf/vhost.conf
Then restart the apache,
/etc/init.d/httpd restart