What is the correct sequence of OSPF adjacency formation?

The correct sequence of OSPF adjacency formation is "Down, Init, 2way, ExStart, Exchange, Loading, Full". This reflects the actual steps that an OSPF router follows to establish a full adjacency with its neighboring routers.

In this sequence, the initial state is "Down," which indicates that no OSPF packets have been exchanged yet. Once two routers detect each other on the link, they move into the "Init" state, where each router sends a hello packet to establish baseline communication. When they receive the hello packets from each other, they enter the "2way" state, confirming that they are aware of each other's presence.

From "2way," they proceed to "ExStart," where the routers negotiate who will be the master and who will be the slave in the process of exchanging database description (DBD) packets. This sets the stage for the "Exchange" state, where the routers share their DBD packets to compare what routing information they have and what they still need.

Next comes the "Loading" state, where routers request and send link-state updates (LSUs) to ensure they have the same link-state database. Finally, once all LSUs are exchanged and acknowledged, the adjacency reaches