Monitoring
Keeping all your applications properly monitored makes it easier to understand if they are up or down.
Astonishingly many online services are not monitored and this has the obvious effect that no one knows when they are working or not.
An important tool in the box would be an online uptime monitoring application like Pingdom or Better Uptime. It can check the uptime every minute by sending pings to your website or service.
Using apps it can help many tech leaders to be able to be reactive and invoke incident management processes when things are down.
Monitoring services can also help doing online testing against important forms or elements, by checking if they are accessible in the code.
Read more in "The CTO Playbook" available on Amazon/Kindle.