The attention network test (ANT), developed based on the triple-network taxonomy by Posner and colleagues, has been widely used to examine the efficacy of alerting, orienting, and executive control in clinical and developmental neuroscience studies. Recent research suggests the imperfect reliability of the behavioral ANT and its variants. However, the classical ANT fMRI task’s test-retest reliability has received little attention. Moreover, it remains ambiguous whether the attention-related intrinsic network components, especially the dorsal attention, ventral attention, and frontoparietal network, manifest acceptable reliability. The present study approaches these issues by utilizing an openly available ANT fMRI dataset for participants with Parkinson’s disease and healthy elderly. The reproducibility of group-level activations across sessions and participant groups and the test-retest reliability at the individual level were examined at the voxel, region, and network levels. The intrinsic network was defined using the Yeo-Schaefer atlas. Our results reveal three critical facets: (1) The overlapping of the group-level contrast map between sessions and between participant groups was unsatisfactory; (2) The reliability of alerting, orienting, and executive, defined as contrast between conditions, was worse than estimates of specific conditions. (3) Dorsal attention, ventral attention, visual, and somatomotor networks showed acceptable reliability for the congruent and incongruent conditions. Our results suggest that specific condition estimates might be used instead of the contrast map for individual or group-difference studies.