Application Probing is a monitoring feature in Citrix Director that automatically launches configured probes to test the availability and responsiveness of published applications.
Citrix added full support for application probing in Citrix Virtual Apps and Desktops 2203 LTSR.
Therefore:
* 2203 LTSR is the oldest LTSR that supports application probing
* 1912 LTSR and 7.15 LTSR # Do not support application probing
* 2402 LTSR # Supports probing, but it is newer, not the oldest
Thus, the earliest LTSR with application probe support is 2203 LTSR.
Documentation References
* Citrix Director # Application Probe Requirements
* CVAD 2203 LTSR Feature Introduction
* CVAD 2402 LTSR Monitoring Enhancements