CCNA OSPF Questions

Setting the interface network type to point-to-point changes adjacency behavior but does not suppress hello packets. Therefore, it does not meet the requirement to prevent hello packet transmission.

Applying a distribute-list out on the interface filters routing updates but does not affect the sending of OSPF hello packets. It does not prevent hello packet transmission on the LAN segment.

This distractor assumes the election is based on current priority values, but OSPF DR election is nonpreemptive; even if R3's priority is higher, it will not become DR unless the current DR fails.

The specific factual error is that timer mismatches affect the neighbor discovery phase, not the database exchange phase.

The specific factual error is that network type affects the election of DR/BDR and adjacency formation, but not the DBD exchange process.

The specific factual error is that area ID mismatches cause OSPF to ignore hello packets, so the adjacency never progresses beyond DOWN.

The problem is not due to missing global addresses; the adjacency is stuck at EXSTART, not at DOWN or INIT.

The show output shows different router IDs (192.168.1.1 and 192.168.1.2), so this is not the issue.

The adjacency is stuck in EXSTART, which is not typically resolved by changing network type; the issue is related to packet exchange.

Mismatched OSPF process IDs do not prevent neighbor formation because process IDs are locally significant identifiers on each router. They do not need to match for adjacency to form, so this option is incorrect.

Missing default routes do not affect OSPF neighbor formation. Default routes influence routing decisions but are not required for establishing OSPF adjacencies, so this option is incorrect.

Different router IDs are necessary for OSPF neighbors to uniquely identify each router. Having different router IDs does not cause adjacency failure, so this option is incorrect.

Priority 0 excludes the router from DR/BDR election entirely; it can only become a DROTHER.

A new router with a higher priority does not trigger a new election unless the existing DR or BDR goes down.

DROTHERs do not form full adjacencies among themselves; they only exchange LSAs via the DR/BDR.

Although removing 'passive-interface default' would also restore OSPF on these interfaces, the solution commands show the preferred method of overriding the default selectively, making this option incorrect for the given scenario.

The network statements on R1 already correctly include the /30 subnets, so there is no need to change wildcard masks.

The OSPF network type defaults to broadcast, which is appropriate for Ethernet links; changing to point-to-point does not resolve the passive-interface issue and would not fix hello suppression.

OSPF routes are installed when EIGRP is present; routing protocols coexist and the route with the lowest AD is selected.

OSPF supports both IPv4 and IPv6; it is not limited to IPv6.

EIGRP routes do not always have a smaller subnet mask; prefix length is determined by the network design, not the routing protocol.

This option is incorrect because static routes are preferred over dynamic routes in OSPF when both are present, regardless of when they were learned. The static route to 10.55.10.0/24 will be used due to its longer prefix match.

This option is incorrect because OSPF routes do not share equal preference with static routes; the static /24 route will be preferred due to its longer prefix length, making it the best match for the specific destination IP.

This option is incorrect because overlapping routes are valid in routing protocols like OSPF, and both routes can coexist in the routing table. The static route to 10.55.10.0/24 is valid and will be preferred due to its longer prefix length.

Candidates mistakenly assume that OSPF process IDs must match globally for proper LSA exchange, but they are only locally significant.

Candidates may think that the network type influences the OSPF LSA type, but it only affects neighbor discovery and DR/BDR election, not the area origin of LSAs.

Candidates sometimes confuse the metric influence with the route type, thinking that OSPF converts routes when the cost exceeds a threshold.

This option is incorrect because OSPF neighbors must be in the same area to form adjacency. Using different areas on the same segment prevents adjacency, so this option contradicts OSPF area rules.

This option is incorrect because OSPF authentication, including message-digest (MD5), is supported on Ethernet interfaces, not just serial links. Authentication is not limited by interface type.

This option is incorrect because OSPF requires valid IP addressing on interfaces to operate. Removing IP addressing disables OSPF on that link, so adjacency cannot form without IP addresses.

This option is incorrect because OSPF can still form adjacencies between routers in different areas, provided they are correctly configured to do so. The issue in this scenario is related to OSPF timers, not area mismatches.

This option is incorrect because OSPF can still exchange multicast packets even if the subnet mask is not configured correctly, as long as the interfaces are up and configured for OSPF. The failure to form an adjacency is more likely due to mismatched OSPF timers.

This option is wrong because OSPF process IDs do not need to match for routers to form an adjacency; they only need to be in the same area and have matching network statements.

This option fails to account for the explicit passive interface state shown on R2. A missing network statement would not cause the interface to be displayed as passive; it would simply not be enrolled in the OSPF process.

This is a common misconception, but process ID mismatch does not affect OSPF neighbor formation. The passive interface status on R2 directly contradicts this as the cause.

The passive interface status would not appear if the only issue were interval mismatches; the interface would still be active and sending hellos. This directly conflicts with the given show output.

A distribute-list requires explicit configuration; its absence makes this an unsubstantiated guess.

Area border routers receive all LSAs from non-backbone areas; the area boundary does not stop LSA propagation to the ABR itself.

The null0 route is a loop-prevention mechanism, not an absolute traffic blocker; more-specific entries in the routing table take precedence.

Neighbor adjacency failure due to timer mismatch would have prevented R2 from becoming BDR at all.

High priority increases the chance of being elected DR, not decrease it.

Point-to-point networks do not have DR/BDR elections, so R2 could not have been BDR.

MTU mismatch can cause OSPF adjacency problems during the database exchange phase, but it does not typically prevent the initial neighbor relationship from forming. Since the question states adjacency cannot form, MTU mismatch is unlikely the primary cause.

Missing router IDs do not prevent OSPF adjacency because routers automatically generate a router ID if none is configured. Therefore, this option is not a valid cause for adjacency failure.

A duplicate static route to 10.1.12.0/30 does not affect OSPF neighbor formation, as static routes are unrelated to OSPF adjacency processes. This option is irrelevant to the adjacency issue.

This is a common misconception; OSPFv3 uses the router ID for neighbor identification, not the process ID.

Link-local addresses are automatically configured and do not affect OSPFv3 adjacency as long as they are unique.

In this scenario, no neighbors are seen, indicating a more fundamental issue like OSPFv3 not being enabled on the interface.

The specific factual error is that the passive-interface command is applied on the wrong router (R2 instead of R1) and the timers are changed on R1 instead of R2.

The specific factual error is that the timer change is applied to the wrong interface (R1's G0/0 already has correct timers) and the passive-interface is applied to the wrong router.

The specific factual error is that the timer values are not changed; they remain mismatched with R1's timers.