Domain Mapping not working

I'm new to the domain mapping process and plugin and attempting to map my first domain.

I have created an A record in the DNS and it directs to the Server IP.
I have added the domain in the sub-site's settings page and it's health status is "Valid."

When I type in the domain into a browser it redirects me to the primary site.

Examples:

Primary site: http://www.mydomain.com
Sub-site: other.mydomain.com
Domain I'm attempting to map: other.com

When I type in other.com I'm redirected to http://www.mydomain.com

Any advice?