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Difficulty: MediumOSPFv2 Network Types and DR/BDR Selection

Match each OSPFv2 interface configuration command or operational trait on the left with its corresponding network type property or election behavior on the right.

  • Interface command `ip ospf priority 0` applied on an Ethernet interfaceExcludes the interface from participating in DR/BDR election, forcing its state to DROTHER
  • Interface command `ip ospf network point-to-point` applied on a multi-access Ethernet linkDisables DR/BDR election while retaining Hello/Dead timers of 10s/40s
  • Default broadcast network type operation on an Ethernet interfacePerforms DR/BDR election using default Hello/Dead timers of 10s/40s
  • Final tie-breaker when OSPF router priorities are equal on a shared segmentHighest OSPF Router ID among candidate routers with non-zero priority

Answer

The interface priority 0 command forces DROTHER state and excludes the router from elections; point-to-point network type on Ethernet suppresses DR/BDR election while using 10s/40s timers; broadcast network type enables DR/BDR election with 10s/40s timers; and equal priority elections break ties using the highest Router ID.
Each item matches its corresponding operational trait: priority 0 forces DROTHER status and excludes the interface from elections; configuring point-to-point on Ethernet suppresses DR/BDR election while using default 10s/40s timers; broadcast networks elect DR/BDR with 10s/40s timers; and equal priority ties are broken by the highest Router ID.

Step-by-Step Solution

1
Analyze OSPF priority 0 behavior
Interface priority 0 prevents a router from ever becoming a Designated Router or Backup Designated Router.
An interface priority of 0 explicitly removes the router from DR/BDR candidate status on multi-access networks.
2
Analyze point-to-point network type behavior on Ethernet media
Modifying network type to point-to-point bypasses DR/BDR election while maintaining standard 10s/40s timers.
Point-to-point connections assume only two routers exist, making DR/BDR election redundant.
3
Analyze default broadcast interface behavior
Broadcast networks elect DR/BDR neighbors and use Hello/Dead timers of 10 seconds and 40 seconds.
Broadcast multi-access links require a DR/BDR to limit adjacency formation across shared media.
4
Identify the election tie-breaker rule
The highest Router ID breaks priority ties among DR candidates.
OSPF DR election precedence evaluates priority first; if priorities match, the highest Router ID wins.

Key Concept

OSPFv2 Network Types and DR/BDR Election Mechanics
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Topics

OSPFv2 Network Types and DR/BDR Selection

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