The answer is that the router will never become the DR or BDR on this segment. Setting the OSPF priority to 0 on a broadcast network interface explicitly prevents the router from participating in the Designated Router and Backup Designated Router election process, meaning it will only form full adjacencies with the elected DR and BDR as a DROTHER. This is a fundamental OSPF behavior tested on the ENCOR 350-401 exam, often appearing in configuration-based questions where a priority of 0 is used to ensure a specific router never assumes the DR/BDR role—a common trap is confusing priority 0 with a low priority value (like 1), which still allows election participation. A reliable memory tip is to think of priority 0 as a "zero chance" flag: if the priority is zero, the router's chance of becoming DR or BDR is absolutely zero.
CCNP WAN Technologies Practice Question
This 350-401 practice question tests your understanding of wan technologies. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
interface GigabitEthernet0/0
ip address 192.168.1.1 255.255.255.0
ip ospf network broadcast
ip ospf priority 0
!
router ospf 1
network 192.168.1.0 0.0.0.255 area 0
What is the effect of setting the OSPF priority to 0 on this interface?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The router will never become the DR or BDR on this segment.
Setting the OSPF priority to 0 on a broadcast network prevents the router from becoming the Designated Router (DR) or Backup Designated Router (BDR). It will never participate in the DR/BDR election and will only form full adjacencies with the DR and BDR.
Key principle: OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
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 never become the DR or BDR on this segment.
Why this is correct
Correct. A priority of 0 means the router is ineligible for DR/BDR election.
The router will have a higher chance of becoming the DR.
Why it's wrong here
Incorrect. Priority 0 makes the router ineligible to become DR or BDR.
✗
The router will only form adjacencies with other routers that have priority 0.
Why it's wrong here
Incorrect. Routers with priority 0 form adjacencies with the DR and BDR, not only with other priority 0 routers.
✗
The router will use a longer hello interval.
Why it's wrong here
Incorrect. Priority does not affect hello interval.
Common exam traps
Common exam trap: OSPF can fail even when IP connectivity looks correct
OSPF neighbour formation depends on matching areas, timers, network type, authentication and passive-interface behaviour. Do not choose an answer only because the devices can ping.
Detailed technical explanation
How to think about this question
OSPF questions usually test the details that control adjacency and route selection. Read the neighbour state, area, router ID and interface configuration before deciding what is wrong.
KKey Concepts to Remember
OSPF neighbours must agree on key parameters.
Router ID selection can affect neighbour relationships and LSDB output.
OSPF cost influences the preferred path.
A route can appear in OSPF information but not become the installed route.
TExam Day Tips
→Check area mismatch first when OSPF adjacency fails.
→Review passive interfaces when a network is advertised but no neighbour forms.
→Use show ip ospf neighbor and show ip route clues carefully.
Key takeaway
OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
Real-world example
How this comes up in practice
A network engineer at a university connects two campus buildings via a fibre link. Both routers run OSPF, but no adjacency forms — even though both routers can ping each other. The engineer finds one router is in area 0 and the other in area 1. OSPF adjacency requires matching area numbers, hello/dead timers, and network type. IP reachability alone is not enough.
What to study next
Got this wrong? Here's your next step.
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related 350-401 OSPF questions on adjacency and route selection.
WAN Technologies — This question tests WAN Technologies — OSPF neighbours must agree on key parameters..
What is the correct answer to this question?
The correct answer is: The router will never become the DR or BDR on this segment. — Setting the OSPF priority to 0 on a broadcast network prevents the router from becoming the Designated Router (DR) or Backup Designated Router (BDR). It will never participate in the DR/BDR election and will only form full adjacencies with the DR and BDR.
What should I do if I get this 350-401 question wrong?
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related 350-401 OSPF questions on adjacency and route selection.
What is the key concept behind this question?
OSPF neighbours must agree on key parameters.
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