Can I test before I make the DNS change?

Yes.  Some organizations desire to test the functionality themselves before switching on live traffic, particularly in areas of the website that are not generally accessible, such as behind a login screen. 

To do this, you can use the IP address of the CNAME and modify the “hosts” file on one or more computers and run some tests.  This overrides DNS for those computers, and directs the web traffic through Protector Air before it goes to the website.  Once testing is complete, you make the DNS changes to put Protector Air in place for all web traffic.  (And don’t forget to undo the changes on the test computers.)