CCNP Practice Question: Examine the following partial configuration on a…

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✓

  The router will send OSPF hello packets every 5 seconds and declare a neighbor dead after 20 seconds of no hello.

  Why this is correct

  This is correct because OSPF hello and dead intervals are configurable per interface, and once configured with 5 and 20 seconds, the router will use those exact values for sending hello packets and for declaring a neighbor unreachable. The dead interval of 20 seconds is four times the hello interval, maintaining the recommended ratio for OSPF stability and fast convergence. This configuration is valid and commonly used to tune OSPF convergence times on point-to-point links.

• ✗

  The router will send OSPF hello packets every 10 seconds and declare a neighbor dead after 40 seconds, overriding the configuration.

  Why it's wrong here

  This is incorrect because the configured hello and dead intervals always take precedence over the OSPF defaults; the router will not revert to the default 10-second hello and 40-second dead interval simply because the values are non-default. The explicit interface configuration of 'ip ospf hello-interval 5' and 'ip ospf dead-interval 20' overrides any default settings. Therefore, the router will continue to use the configured timers, not override them.

• ✗

  The configuration is invalid because the dead interval must be exactly four times the hello interval.

  Why it's wrong here

  This is incorrect because OSPF does not enforce a strict requirement that the dead interval be exactly four times the hello interval; it only requires the dead interval to be greater than the hello interval, and Cisco recommends a multiple of four for stability. In fact, the configured dead interval of 20 is exactly four times the hello of 5, so the configuration meets the recommended ratio and is perfectly valid. A router would accept any dead interval greater than the hello interval, as long as neighbors match.

• ✗

  The router will not form OSPF adjacencies because the hello and dead intervals are not default.

  Why it's wrong here

  This is incorrect because OSPF neighbor adjacency requires only that the hello and dead intervals match between the two routers; using non-default values does not prevent adjacency formation. When both interfaces are configured with the same non-default timers (5 and 20), the routers will successfully form an OSPF adjacency. The default timers are simply defaults, not mandated values, so this statement is false.