An inactive cluster node has either become unreachable or has been stopped. When you delete a stopped cluster node, the operation does not remove cookie and other synchronized data. To find which cluster nodes are inactive, use the cluster_info command:

/opt/pingidentity/ase/bin/ cluster_info -u admin -p 
cluster id : ase_cluster
cluster nodes active active inactive active inactive
tasks.aseservice2:8020 not resolved

Using the cluster_info command output, you can remove the inactive cluster nodes and

To delete the inactive node, use the delete_cluster_node command:
/opt/pingidentity/ase/bin/ delete_cluster_node <IP:Port>