I develop custom Web sites using WordPress as a CMS, and use it to run my Web Development Blog.Author has 11.2K answers and 19.5M answer views6y
If both installations are with the same hosting provider and the content will be identical you can make this work by having them share the same database.
First create site A on domain A. This will be the site where you add/edit content.
Next do a clean WordPress install on Domain B. Edit the wp-config.php file for domain B to use the same database as the one on domain A. Editing wp-config.php has information about editing this file.
The database specifies the site url, so we will need to change the url for domain B. An easy way to do this is to code this into wp-config.php as well. This hardcodes the url. Just add the following and change the url to the one for domain B.