Citrix officially supports two primary methods for ensuring License Server redundancy. The first is creating a standby (or backup) License Server. This involves installing the same license files on a second server; if the primary server fails, administrators must manually reconfigure Citrix products to point to the standby server. The second, more robust option is to install the License Server on a Microsoft Failover Cluster. This active/passive configuration provides automatic failover, where the cluster service moves the License Server role to a passive node if the active node becomes unavailable, ensuring continuous service without manual intervention.

A. Use Citrix Application Delivery Management (ADM) High Availability (HA).

ADM's High Availability feature provides redundancy for the ADM service itself, not for external components like the Citrix License Server.

B. Use Citrix Application Delivery Management (ADM) Load Balancing.

Load balancing is not a supported high availability solution for License Servers, as license files are bound to a specific, case-sensitive hostname.

E. Configure a Citrix License Server High Availability (HA) pair.

The Citrix License Server does not have a native, built-in high availability pairing feature; redundancy is achieved through underlying platform technologies like clustering.

1. Citrix Licensing Documentation, "High availability and redundancy": This official document explicitly outlines the two supported methods. It states, "You can cluster license servers to provide failover... You can have a second license server as a backup. If the primary license server fails, you can change the product settings to point to the backup license server."

Source: Citrix Product Documentation, Licensing, Current Release, "High availability and redundancy."

2. Citrix Virtual Apps and Desktops Documentation, "Licensing": This documentation reiterates the supported options for license server availability within the context of a Virtual Apps and Desktops environment. It details the use of a simple backup server and a more complex but automated active/passive cluster.

Source: Citrix Product Documentation, Citrix Virtual Apps and Desktops, Current Release, "Licensing."

3. Citrix Tech Zone, "Design Decision: High Availability for Citrix Licensing": This reference architecture guide discusses the design choices for licensing. It confirms, "For Citrix Licensing, there are two options for high availability: Active/Passive Cluster or a Secondary License Server."

Source: Citrix Tech Zone, Reference Architectures, "Design Decision: High Availability for Citrix Licensing."