What characterizes the OSPF Two-Way State?

The two-way state in OSPF (Open Shortest Path First) is a significant step in the OSPF neighbor adjacency establishment process, primarily characterized by the exchange of Hello packets. When routers detect each other through the Hello protocol, they enter this state, indicating that they can communicate. In this state, a Hello packet is sent back from one router to the other using unicast, confirming that both routers can see each other and establishing bidirectional communication.

This mutual acknowledgment is crucial, as it allows the routers to recognize their neighbors and set the groundwork for further exchanges, such as Link State Advertisements (LSAs). The two-way state is especially important in multi-access networks, like Ethernet, where routers need to determine which will become the designated router and backup designated router to minimize the number of adjacencies formed.

Therefore, the correct characteristic of the OSPF Two-Way State is the unicast response via the Hello packet, affirming both routers' receipt of each other's Hello messages and readiness to engage in further OSPF functions.