XMission Control Panel/Server Tab/Host Files
From XMission Wiki
Setting up Host Files
Linux
Edit your hosts file though a terminal
sudo vim /etc/hosts
The output will look similar to this
127.0.0.1 localhost 127.0.1.1 example.stafftest.cloud.xmission.com example.stafftest.cloud example.stafftest
From here you will want to add the IP address of your server and the hostname (eg. 166.70.181.4 example.com www.example.com) Should look like this
127.0.0.1 localhost 166.70.53.145 example.stafftest.cloud.xmission.com example.stafftest.cloud example.stafftest
Save your work and close your file by pressing the ESC key and typing :wq followed by enter. Now when you go to your domain on your computer it will resolve to the IP address you specified.