Cisco Certified Support Technician (CCST) NetworkingIP ConnectivityMedium
A network engineer is configuring OSPF on a router. They need to ensure that the router becomes the Designated Router (DR) for a specific multi-access segment. Which OSPF parameter should be adjusted to influence this election, assuming all other parameters are default?
- ARouter ID
- BProcess ID
- CPriority
- DHello Timer
Show answer & explanationAnswer & explanation
Correct answer: C. Priority
The OSPF DR election process is primarily influenced by the OSPF interface priority. A higher priority value (0-255) makes a router more likely to become the DR. If priorities are equal, the router with the highest Router ID wins.
Why the other options are wrong
- A. Router ID is used as a tie-breaker if priorities are equal, but priority is the primary factor for influencing DR election.
- B. The OSPF process ID is locally significant and does not influence DR election.
- D. The Hello Timer influences the frequency of neighbor discovery and keepalives, but not the DR election itself.
OSPF DR/BDR Election
The OSPF Designated Router (DR) and Backup Designated Router (BDR) election process on multi-access networks is determined by router priority and then Router ID.
- Highest OSPF interface priority wins DR election.
- If priorities are equal, highest Router ID wins.
- A priority of 0 prevents a router from becoming DR/BDR.
Memory trick: DR's Priority Rules, Router ID Resolves.