Crea o inserta en tu .htacces.
Código .htacces:
Ver originalRewriteEngine On
RewriteCond %{HTTP_HOST} ^www.dominio1.com$ [NC]
RewriteRule ^(.*)$ http://www.dominio2.com/ [R=301,L]
RewriteCond %{HTTP_HOST} ^dominio1.com$ [NC]
RewriteRule ^(.*)$ http://www.dominio2.com/ [R=301,L]