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Which OSPF network type on Ethernet performs a DR and BDR election by default?

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Which OSPF network type on Ethernet performs a DR and BDR election by default?

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Answer choices

Why each option matters

Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.

A

Distractor review

Point-to-point

Point-to-point links do not elect a DR/BDR.

B

Best answer

Broadcast

Correct. Ethernet defaults to the broadcast network type.

C

Distractor review

Point-to-multipoint nonbroadcast

That is not the default Ethernet behavior.

D

Distractor review

Loopback

Loopbacks do not participate like broadcast segments.

Common exam trap

Common exam trap: answer the scenario, not the keyword

A frequent exam trap is selecting point-to-point or point-to-multipoint nonbroadcast as the network type that performs DR/BDR elections. Candidates often assume any multi-router link requires DR/BDR, but OSPF only elects DR/BDR on broadcast and NBMA networks. Point-to-point links connect exactly two routers and do not need DR/BDR, while point-to-multipoint nonbroadcast requires manual neighbor configuration and does not elect DR/BDR by default. Misunderstanding these distinctions leads to incorrect answers. Remember, Ethernet interfaces default to broadcast network type, which triggers DR/BDR elections automatically.

Technical deep dive

How to think about this question

OSPF (Open Shortest Path First) is a link-state routing protocol that uses different network types to optimize routing behavior based on the underlying Layer 2 technology. Ethernet interfaces in OSPF default to the broadcast network type, which supports multiple devices on the same segment. This network type enables OSPF routers to elect a Designated Router (DR) and a Backup Designated Router (BDR) to reduce the amount of routing protocol traffic and streamline link-state updates. The DR and BDR election process occurs only on broadcast and nonbroadcast multiaccess (NBMA) networks where multiple routers share the same segment. On Ethernet, which is a broadcast multiaccess network, OSPF routers automatically perform this election to minimize flooding of LSAs (Link State Advertisements) and improve network efficiency. Point-to-point and loopback interfaces do not elect DR/BDR because they connect only two routers or are virtual interfaces, respectively. A common exam trap is confusing the network types and their behaviors. For example, point-to-point links do not elect DR/BDR, so selecting that option is incorrect despite it being a common interface type. Understanding that Ethernet defaults to broadcast network type and thus performs DR/BDR election is critical for CCNA routing questions. Practically, this election reduces OSPF overhead in multi-router Ethernet segments and ensures stable routing adjacencies.

KKey Concepts to Remember

  • OSPF uses different network types to optimize routing behavior based on the Layer 2 media characteristics and topology.
  • Ethernet interfaces in OSPF default to the broadcast network type, which supports multiple routers on the same segment.
  • Broadcast network type in OSPF triggers automatic election of a Designated Router (DR) and Backup Designated Router (BDR) to reduce routing overhead.
  • Point-to-point OSPF network types connect exactly two routers and do not perform DR/BDR elections.
  • Loopback interfaces do not participate in OSPF DR/BDR elections because they are virtual and not multiaccess.
  • Point-to-multipoint nonbroadcast OSPF network types require manual neighbor configuration and do not elect DR/BDR by default.
  • DR and BDR elections reduce OSPF flooding by centralizing link-state advertisement distribution on multiaccess networks.
  • Understanding OSPF network types and their DR/BDR election behavior is essential for correctly answering CCNA routing questions.

TExam Day Tips

  • Watch for words such as best, first, most likely and least administrative effort.
  • Review why wrong options are wrong, not only why the correct option is correct.

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More questions from this exam

Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.

Question 1

A router learns the same prefix from both OSPF and EIGRP. Which route is installed by default?

Question 2

A router shows this output: R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/DR 00:00:34 192.168.12.2 GigabitEthernet0/0 10.1.1.3 1 2WAY/DROTHER 00:00:39 192.168.12.3 GigabitEthernet0/0 Which statement is correct?

Question 3

What is the OSPF metric called?

Question 4

A non-root switch has two uplinks toward the root bridge. One path has a lower total STP cost than the other. What role will the lower-cost uplink have?

Question 5

A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that web browsing to a server by IP address fails, but ping works. Which statement best explains the behavior?

Question 6

A router learns route 198.51.100.0/24 from OSPF with AD 110 and also has a static route to the same prefix configured with AD 150. Which route is installed?

FAQ

Questions learners often ask

What does this 200-301 question test?

OSPF uses different network types to optimize routing behavior based on the Layer 2 media characteristics and topology.

What is the correct answer to this question?

The correct answer is: Broadcast — Broadcast multiaccess networks such as Ethernet elect a DR and BDR by default.

What should I do if I get this 200-301 question wrong?

Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.

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