If the hello timer setting for an OSPF-enabled router is changed to 20 seconds, what is the new default dead interval time?

In OSPF (Open Shortest Path First), the dead interval is a critical timing parameter that specifies how long a router will wait to hear from a neighbor before considering that neighbor down. The default dead interval is typically set to four times the hello interval.

In this scenario, if the hello timer is changed to 20 seconds, the calculation for the new dead interval would be as follows:

[ \text{Dead interval} = 4 \times \text{Hello interval} ]

[ \text{Dead interval} = 4 \times 20\ seconds = 80\ seconds ]

Thus, when the hello timer is adjusted to 20 seconds, the resulting dead interval automatically becomes 80 seconds. This relationship is key to understanding how OSPF manages neighbor relationships and maintains network stability. A consistent hello and dead interval across routers in the same network segment is essential for proper OSPF operation, facilitating adjacency creation and maintaining the OSPF database integrity.