Application Delivery Controllers (ADCs) are an evolution of server load balancers (SLB) that combine traditional load-balancing capabilities with features like automatic application health checks, SSL offload, proxy and reverse proxy capabilities, RAM caching, TCP reuse, web and DNS application firewalls (WAF and DAF) and application access management (AAM).
Together these features in an Application Delivery Controller work to ensure that an enterprise’s data center applications and networks remain highly available, accelerated and secure. At the heart of an Application Delivery Controller is its load-balancing capabilities, which automatically distribute processing and communications evenly across computer networks and servers so that no single device is overwhelmed, preventing potential downtime or performance degradation.
Origin of the Term Application Delivery Controller and ADC Vendors
Application Delivery Controller and the closely-related term Application Delivery Network (ADN) were marketing monikers first promoted by F5 Networks and later by competing ADC vendors to represent hardware and software solutions that provide front-end intelligence to facilitate and optimize application flows from client to server and back to the client.
Application Delivery Controllers are currently available from a wide variety of vendors, including most notably F5 Networks, Citrix, KEMP Technologies, and Fortinet. Another well-known networking firm, Cisco, was a key player in the ADC sector until 2012, when it decided to exit the ADC market.