When multiple Online Responders are used, they need to be organized into a logical framework called an Online Responder Array. Because Online Responders are designed to respond to individual certificate status requests, an Online Responder Array helps distribute status requests among multiple, geographically dispersed Online Responders.

One Online Responder in the Array must be designated as the Array controller. The configuration information for the Array controller determines the configuration options on other members of the Array.

Setting up an Array requires advance planning based on the following:

  • The number and location of the certification authorities (CAs) being supported by the Array.

  • The number of clients who will request certificates from the CAs and their locations.

  • The network connectivity between clients, CAs, and potential Online Responders.

  • The volume of certificate enrollments, certificate revocations, and certificate status requests that the organization's public key infrastructure (PKI) handles.

  • The need for redundancy in case individual Online Responders become unavailable.