A customer recently opened a ticket because there were problems starting their multi site cluster. Some nodes were working and some were not. Examination of their systems, specifically the Network configuration page, revealed that they were using two different subnet masks, 24 bits in some places and 23 bits in others. Discussions with the customer's network admin revealed that the mixed masks did not match the network admin's expectations. They stopped the cluster, corrected the masks and restarted the cluster. This resolved the problem.