This page applies to Appian Cloud only. It may not reflect the differences with Appian Government Cloud.
Appian Cloud maintains a shared, global, highly available tier of web servers running in all supported regions which serve static and dynamic content to end users around the world. These web servers help to improve page load times, decrease load on customer app servers, and block unwanted traffic using Trusted IP lists.
Demand is monitored and capacity is automatically scaled up if demand increases.
Appian Cloud's Web Layer is designed with redundancy in mind. In the event of a web server hardware failure, our systems will automatically route requests to other healthy web servers, while restarting the web server that encountered a hardware failure. In the event of an application server hardware failure or availability zone failure on environments configured with High Availability (HA), our web servers will automatically stop routing traffic to the failed instance or availability zone and route traffic to the healthy environments or zones. For more information on High Availiability in Appian Cloud, see our Full Documentation.
Appian Cloud's web layer implements Denial of Service (DoS) protections to help ensure its availability. If an environment experiences an unusually high level of traffic, the DoS protections may be triggered. In the event that DoS protections are triggered, new requests to the affected environment may be blocked until the in-flight requests are completed or the high load subsides.
Appian Cloud Web Layer