We are talking about how to Configure and troubleshoot OSPF over a network, you must have a good understanding of the underlying network topology. The neighbor discovery mechanism, election of Designated Router (DR) and Backup Designated Router (BDR)...
http://www.ebrahma.com/2013/10/ospf-over-nbma-topology/Labels: ip-ospf-network, NBMA, NBMA-Topology-Summary, OSPF-over-NBMA-Topology, Topology-Summary