Domain Pointers in DirectAdmin (DA) is a function that allows multiple domains to run in one source code, database. Similar to the Alias domain on cPanel; and to set this function, you do the following:
Access to DirectAdmin => click Account Manager => Domain Pointers
Click Create Domain Pointers
As shown below, you enter the domain and click Create.
Note: After performing the above steps, for Pointers Domain to work, you need to point that domain name to IP for it to take effect.