An OSPF broadcast segment has four OSPF-speaking routers. How many 2Way OSPF sessions does a router in the DR other state have?

In an OSPF (Open Shortest Path First) network, routers use a mechanism to establish adjacencies, which allows them to exchange routing information. When routers are configured as OSPF speakers on a broadcast network, they go through various states to establish these adjacencies.

In a broadcast segment with multiple OSPF routers, only one router is elected as the Designated Router (DR), and the others are considered Backup Designated Routers (BDR) or neighbors. A router that is in the DR other state (meaning it is not the DR or the BDR) will only maintain a 2Way adjacency session with the DR and the BDR.

Therefore, a router in the DR other state will establish a session with the DR and one session with its BDR, resulting in a total of two 2Way sessions. However, it will not form a full adjacency with every other OSPF router; it will only have bidirectional communication established with the DR and the BDR.

This leads to the conclusion that the actual number of 2Way OSPF sessions that a router in the DR other state has with the other routers in the segment is limited to just one session, specifically with the DR.