How do I fix an "Error sending exam start notification" issue with Respondus Monitor?

This error will occur when the exam requires Respondus Monitor, but the computer and/or network is not able to communicate with the Respondus Monitor server. The following domain must be permitted on your computer and network: 

*.smc-service-cloud.respondus2.com

Other essential domains are:

Server profiles: server-profiles-respondus-com.s3-external-1.amazonaws.com
Update server: static-public-downloads-cloud.respondus.com
Installs/Downloads: *.respondus.com
Help Center: help-center-respondus-com.s3.amazonaws.com