Site accessible via multi domains

We have our site accessible via 2 domains admin.domain.com and http://www.domain.com running on a 3 server setup (1 for admin, 2 for www), we access wp-admin via the admin.domain.com address.

Redirection creates rules with the base source domain as admin.domain.com, I would like to change that to http://www.domain.com

Whats the best way to achieve this?

Thanks,

Chris.

https://wordpress.org/plugins/redirection/