CCNA 200-301 v1.1 reference — IP Connectivity
OSPF network types and DR election
Point-to-point and broadcast network types, DR/BDR election behavior and non-preemption, and their timer and next-hop differences.
Objective 3.4v1.1 exam target
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OSPF network types on the exam
| Property | Broadcast (Ethernet default) | Point-to-point |
|---|---|---|
| DR/BDR election | Yes — one DR + one BDR per segment | No — no election |
| Hello / dead | 10 s / 40 s | 10 s / 40 s |
| Multicast use | 224.0.0.5 all routers, 224.0.0.6 DR/BDR | All traffic to 224.0.0.5 |
| Next-hop behavior | Next hop = originating router (not the DR) | Direct neighbor |
| Use | Multiaccess segments | Serial, GRE tunnels, PtP Ethernet |
DR election is non-preemptive: once a DR exists, a new router with higher priority does NOT take over — the current DR keeps its role until it fails or the segment resets. This surprises everyone once.
OSPF default timers
| Parameter | Broadcast / point-to-point | Non-broadcast (NBMA) |
|---|---|---|
| Hello interval | 10 s | 30 s |
| Dead interval | 40 s | 120 s |
| Retransmit LSA | 5 s | 5 s |
| LSA refresh | 30 min (originator) | 30 min |
Hello/dead must match between neighbors; mismatched timers alone prevent adjacency.
$ show ip ospf neighbor (roles)
1.1.1.1 0 2-WAY/DROTHER 00:00:39 10.0.0.4 Gi0/2DROTHER-to-DROTHER stays 2-WAY; only DR/BDR reach FULL with this observer.2.2.2.2 100 FULL/DR 00:00:35 10.0.0.2 Gi0/2Highest priority — the DR.3.3.3.3 50 FULL/BDR 00:00:37 10.0.0.3 Gi0/2Next in line — the BDR.Related resources
Sources
- Cisco CCNA 200-301 v1.1 Exam Topics (official PDF) — reviewed 2026-11-02
- RFC 2328 — OSPF Version 2 — reviewed 2026-11-02
- Cisco — IP Routing: OSPF Command Reference — reviewed 2026-11-02
Targets CCNA 200-301 v1.1 objectives. Supplemental blocks are labeled beyond exam scope.