CCNA OSPF Questions

OSPFv2 supports only IPv4; OSPFv3 is required for IPv6 routing.

OSPFv3 uses a 32-bit router-id, which must be manually configured or derived from an IPv4 address; without it, the process cannot operate.

Verification commands like 'show ospfv3 neighbor' and 'show ipv6 route ospf' are necessary to ensure OSPFv3 is functioning correctly.

This statement is false because passive-interface does not prevent the network from being advertised; the prefix is still injected into the OSPF LSAs.

Passive-interface only stops OSPF control packets; data traffic forwarding continues normally on the interface.

The passive-interface command does not remove the network from the OSPF routing table; the network is still reachable via other interfaces.

Option B is incorrect because metrics like OSPF cost are only compared among routes from the same protocol; the router does not compare OSPF cost against static route administrative distance.

Option D is incorrect because routes from different sources with different administrative distances do not qualify for equal-cost multipath (ECMP), so both routes are not installed simultaneously.

Skips the more likely and fundamental subnet mask check, which would render timer issues irrelevant until resolved.

Ignores the more foundational IP addressing check that could also cause the issue, and area troubleshooting would be misleading if the subnet mask is incorrect.

Jumps to an OSPF-specific command without first verifying the fundamental IP subnet configuration, which is a more direct cause of failed adjacencies on broadcast links.

The 2-WAY state confirms bidirectional communication between OSPF neighbors but does not indicate that the full link-state database has been exchanged. It is an intermediate step before full adjacency.

EXSTART is the initial phase of database exchange where routers negotiate master-slave roles and sequence numbers. It does not mean the databases are fully synchronized yet.

INIT state means a router has received a hello packet from a neighbor but has not confirmed bidirectional communication, so full database exchange has not started.

The OSPF /24 route is less specific than the static /25 route. Since longest-prefix match prefers the more specific route, the OSPF route is not used for 192.168.1.200.

Both routes do not automatically load-balance because they have different prefix lengths. Load balancing requires equal prefix length and equal cost routes, which is not the case here.

Neither route is incorrect because overlapping routes are common and resolved by longest-prefix match. The router uses the more specific static /25 route, so traffic is forwarded correctly.

The passive-interface default command would block Hellos, preventing the adjacency from ever reaching the EXSTART/EXCHANGE state.

An OSPF area mismatch would cause Hellos to be ignored, so the adjacency would not progress past the Down or Init state.

Conflicting router IDs would prevent the routers from becoming neighbors at all, as OSPF requires unique router IDs within an area.

Static routes do not always win; they have a default administrative distance of 1, but in this scenario the static route was configured with AD 150, which is higher than OSPF's AD 110. Therefore, the OSPF route is preferred.

A router installs only the best route (lowest AD) for a given prefix into the routing table. Different AD values do not cause both routes to be installed; the route with the lower AD is chosen.

A floating static route is a static route with a higher AD than the dynamic route, so it remains inactive as a backup. In this case, the static route is floating, but it is still valid and will be used if the OSPF route is lost. The question asks which route is installed, and the OSPF route is installed, not neither.

Router ID duplication does not explain a completely empty neighbor table; neighbors would still be detected via hellos.

Network type mismatch would likely still result in hellos being received and a neighbor entry appearing, just not advancing to full adjacency. The complete absence of neighbors points to a transport issue.

Candidates often remember MTU mismatch as a frequent OSPF problem, but it manifests after neighbor discovery, not as a complete lack of neighbors.

Incorrect because OSPF fully supports GigabitEthernet interfaces. There is no restriction on running OSPF on these interfaces in Cisco IOS.

Incorrect because both routers being in area 0 is necessary for adjacency on that segment. Matching area IDs help form adjacency rather than prevent it.

Incorrect because router IDs must be unique, not identical. Matching router IDs do not cause adjacency to form; in fact, duplicate router IDs cause routing problems but not adjacency failure due to subnet mismatch.

Option B is incorrect because static routes do not always override OSPF routes regardless of specificity. Prefix length is evaluated before administrative distance, so a less specific static route would not override a more specific OSPF route.

Option C is incorrect because OSPF can route any IP address range, including Class B networks like 172.16.0.0/16. There is no limitation on OSPF routing based on IP class.

Option D is incorrect because the routing decision here is based on prefix length, not on comparing OSPF metric and static route administrative distance. The static route’s longer prefix length takes precedence.

This option is incorrect because OSPF’s administrative distance of 110 is higher than EIGRP’s 90, so OSPF routes are less preferred when both advertise the same prefix length.

This option is incorrect because routers do not treat routes from different protocols with equal administrative distance; they prefer the route with the lower administrative distance, so both routes are not equally preferred.

This option is incorrect because routers can and often do receive overlapping routes from multiple routing protocols and must compare administrative distance to choose the best route.

This option is incorrect because route preference is determined by administrative distance, not by a blanket rule that dynamic routes always beat static routes.

This option is incorrect because identical prefix length alone does not guarantee equal route preference; administrative distance is the deciding factor.

This option is incorrect because routers do not drop duplicate routing information; instead, they choose the best route based on administrative distance.

The question states the serial link is up/up on both sides, meaning the interface is not administratively down. An administratively down interface would show as 'administratively down' in the interface status, not 'up/up'.

Both interfaces have IPv6 addresses in the 2001:DB8:1:1::/64 subnet, so the subnet matches. OSPFv3 does not require interfaces to be in the same subnet for adjacency, but it does require link-local addresses to be reachable. However, the given addresses are global unicast, and the subnet match is not the issue here.

The router-id is configured on R2 as 2.2.2.2, as stated in the existing explanation. OSPFv3 requires a router-id, and it is present, so this is not the cause.

Using a static route with administrative distance 1 makes it the most preferred route immediately, overriding the OSPF-learned route. This does not meet the requirement of using the static route only when the OSPF route disappears.

Setting a static route with metric 0 does not influence route preference between static and OSPF routes because metrics affect path selection within routing protocols, not across different route sources.

Redistributing the static route into OSPF advertises it dynamically but does not create a backup route that activates only when the OSPF route disappears. Redistribution is unnecessary for this backup behavior.

Incorrect. While using a loopback interface as the router ID is recommended for stability, it is not required for OSPF neighbor adjacency to form.

Incorrect. A /30 subnet mask is valid for point-to-point OSPF links and does not prevent neighbor relationships from forming.

Incorrect. The Designated Router (DR) election occurs after adjacency formation and does not prevent neighbors from forming if area IDs mismatch.

Lowest administrative distance is incorrect because administrative distance is used to compare routes from different routing protocols, not to select between multiple OSPF-learned routes. Within OSPF, all routes have the same administrative distance, so this criterion does not apply.

Highest bandwidth of the first hop only is incorrect because OSPF considers the cumulative cost of the entire path, not just the bandwidth of the first hop. Focusing only on the first hop bandwidth ignores the cost of subsequent links.

Lowest next-hop IP address is incorrect because OSPF does not use the next-hop IP address as a criterion for route selection. The protocol relies exclusively on the cost metric to determine the best path.

Loopback0 is not enabled for OSPF, so its prefix is not advertised into OSPF.

The 'network' command is invalid in OSPFv3 for IPv6; only interface-level 'ipv6 ospf ... area' commands are used.

Applying 'passive-interface GigabitEthernet0/0' prevents OSPF from forming a neighbor adjacency on the link, breaking the verification of neighbor state.

The show ip route command does not provide interface-level details such as encapsulation or clock rate; it only shows routing information.

Ping does not provide detailed interface status or configuration information; it only indicates whether the neighbor is reachable, not why it is not.

The running-config shows the intended configuration but not the current operational state; for example, it won't show if the interface is administratively down unless you check the shutdown command.

Candidates assume that OSPF adjacency failures on Ethernet links are often due to network type mismatches, without considering that the default settings match.

Candidates may remember that duplicate router‑IDs break OSPF and jump to this conclusion without first analyzing the simpler configuration issue.

Many students learn that timer mismatches are a common OSPF problem and may incorrectly assume they are the cause when the real issue is a basic configuration oversight.

Both routers are explicitly in OSPF area 0, so they are not in different areas.

OSPF neighbor formation does not depend on matching hostnames; router IDs and interface parameters are what matter.

Since the routers can ping each other, IP reachability exists, indicating the subnet mask is not preventing OSPF multicast packets from being delivered.

Static routes do not always override dynamic routes; route selection is based on administrative distance. OSPF has a default AD of 110, which is lower than 200, so the OSPF route is preferred. The statement that static routes always win is incorrect because AD values determine preference.

Routers install only the best route (lowest AD) for a given destination in the routing table, unless equal-cost multipath (ECMP) is configured with identical metrics. Since OSPF and static routes have different ADs, they are not installed simultaneously; only the OSPF route is used.

The router does not remove the OSPF route because the static route has a manually configured distance. The OSPF route has a lower AD (110) than the static route's AD (200), so OSPF remains the preferred route and stays in the routing table.

This misinterprets AD: after the primary route is gone, any route with a higher AD (i.e., lower numeric value) is no longer present, so the floating static route should be installed if reachable.

Permanent is rarely needed and does not make a route usable when the interface is down; it only keeps the routing table entry present, but traffic cannot be forwarded.

Changing a static route metric is not possible, and even if it were, it would not change the fact that the specified interface is down.

An OSPF area mismatch prevents routers from forming a full adjacency; they typically remain in the INIT or 2-WAY state, not EXSTART. The EXSTART state indicates that the routers have already exchanged Hello packets and are attempting to negotiate the master/slave relationship, which requires matching area IDs.

Duplicate router IDs cause OSPF to behave unpredictably, often resulting in flapping adjacencies or multiple neighbors with the same ID, but they do not typically cause a stuck EXSTART state on a single link. The routers would still progress through the states, but the adjacency may be unstable.

A missing default route on R2 does not affect OSPF adjacency formation. OSPF neighbors exchange routing information using multicast Hello and DD packets, which do not require a default route. The adjacency process is independent of the routing table content.

This places the adjacency in area 1, not area 0 as required, and does not fix the timer mismatch on R2.

This does not fix the hello/dead timer mismatch; MTU is already matching at 1500.

This leaves the hello interval mismatched (10 vs 5) and alters the dead interval unnecessarily; R2 needs hello interval set to 5, not dead interval.

Metrics from different routing protocols are not comparable because each protocol uses its own metric calculation (e.g., OSPF uses cost based on bandwidth, EIGRP uses composite metric based on bandwidth and delay). The router uses administrative distance to choose between routes from different protocols, not metric values.

A router installs only the best route to a destination in the routing table, unless equal-cost load balancing is configured. Since OSPF and EIGRP have different administrative distances, only the route with the lower AD is installed. Both routes cannot be installed simultaneously for the same prefix.

The router does compare routes from different protocols using administrative distance, not metrics. Since the metrics are from different protocols, they are not directly comparable, but the router still selects one route based on AD. Therefore, one route will be installed.

This option is incorrect because a static route with an administrative distance of 250 does not override the OSPF default route, which has a lower AD of 110. The high AD prevents immediate override.

This option is incorrect because the static default route does not cause the router to ignore all default routes. Instead, it remains as a backup and only becomes active if the OSPF route disappears.

This option is incorrect because administrative distance does not change the route prefix or convert a default route into a host route. It only influences route preference and selection.

The OSPF 10.0.0.0/8 route is less specific than the static 10.10.0.0/16 route. Since the router uses longest-prefix match, the broader /8 route is not selected for traffic destined to 10.10.20.1.

The default route would only be used if no more specific matching routes exist. Since both OSPF and static routes match, and the static route is more specific, the default route is not used here.

Overlapping networks are common in routing tables and do not prevent route selection. The router resolves overlapping prefixes by choosing the longest-prefix match, so this option is incorrect.

This option is incorrect because static routes do not always beat dynamic routes; the static route must have a lower administrative distance to be preferred, which is not the case here due to the floating static’s higher AD.

This option is incorrect because routing protocols are compared first by administrative distance, not by their internal metrics; RIP’s metric does not override OSPF’s lower AD.

This option is incorrect because equal prefix length alone does not guarantee load balancing; routes must have matching attributes and equal administrative distances for equal-cost multipath (ECMP) to occur.

The specific factual error is that the adjacency is stuck due to timer mismatch, not network type mismatch.

The specific factual error is that the configuration should be applied to R1, not R2, as per the question context.

The specific factual error is that both hello and dead intervals must match; changing only one leaves a mismatch.

The specific factual error: Changing hello intervals is not the standard fix for a point-to-point link not forming adjacency; the network type is the primary issue.

The specific factual error: Setting priority to 0 does not eliminate the DR/BDR election process; it only ensures the router does not participate as DR/BDR.

The specific factual error: The broadcast network type is already the default on Ethernet; the command is redundant and does not address the need for a point-to-point network type.

OSPFv2 does not natively support IPv6; OSPFv3 is required for IPv6 routing.

Link-state advertisements (LSAs) are refreshed every 30 minutes by default, not every 30 seconds.

OSPF router IDs must be unique throughout the OSPF domain; routers in the same area can have different router IDs.

This option incorrectly states that static routes always override dynamic routes. In Cisco routing, static routes only override dynamic routes if their administrative distance is lower. Since the floating static route has a higher AD (150) than OSPF (110), it is not preferred here.

This option is incorrect because load balancing only occurs between routes with equal administrative distances and metrics. Here, the OSPF and floating static routes have different ADs, so only the route with the lower AD is active.

This option is false because OSPF can advertise and learn default routes using the 'default-information originate' command. Therefore, OSPF can carry a default route, making this statement incorrect.

The exhibit shows the static route is configured, so the issue is not that it is missing.

An administrative distance of 200 is appropriate for a floating static route to be less preferred than OSPF (AD 110) but still usable as a backup.

A default route (0.0.0.0/0) does not override a more specific route like 10.10.10.0/24; the longest prefix match rule ensures the specific route is preferred.

The specific factual error is that OSPFv3 uses interface-level configuration, not network statements like OSPFv2 for IPv4.

The specific factual error is that OSPFv3 must be enabled on all interfaces that should participate in the routing process, including loopback interfaces.

The specific factual error is that OSPF router-ids must be unique. Using the same router-id on both routers prevents proper neighbor formation.

This option is incorrect because router hostnames do not affect OSPF neighbor relationships. OSPF adjacency depends on interface-level parameters, not device names, so identical hostnames are not required.

This option is incorrect because converting the link to a trunk is irrelevant for OSPF adjacency on routed interfaces. OSPF operates on Layer 3 interfaces, and trunking is a Layer 2 concept used for VLAN tagging, not required for OSPF neighbor formation.

This option is incorrect because static routes are not necessary for OSPF adjacency. OSPF dynamically discovers neighbors and exchanges routing information without requiring preconfigured static routes.

Incorrect because router IDs must be unique within the OSPF domain, not identical. Identical router IDs cause routing conflicts and prevent proper operation.

Incorrect because the OSPF process ID is locally significant to each router and does not need to match between neighbors for adjacency formation.

The 2-Way state is a normal OSPF neighbor state on broadcast multiaccess networks for non-DR/BDR routers (DROTHERs). It indicates that bidirectional communication has been established, but full adjacency is not required because they do not exchange LSAs directly. This is not a failure.

A duplicate router ID would cause OSPF neighbor state to oscillate or remain in EXSTART/EXCHANGE, not stabilize in 2-Way. The output shows a stable 2-Way state, which is normal for DROTHERs. Duplicate IDs would also generate error messages in the logs.

A passive interface in OSPF does not send Hello packets and therefore cannot form any neighbor adjacency. The output shows two neighbors in valid states (FULL and 2-Way), which proves the interface is active and sending Hellos.

A higher OSPF metric indicates a less desirable path, as OSPF uses cost as its metric where lower cost is preferred. Selecting a higher metric path would contradict the fundamental routing principle of choosing the best path based on lowest metric.

Equal administrative distance does not imply equal preference when metrics differ. The router compares metrics within the same routing protocol; if metrics are different, the lower metric path is chosen, not both.

OSPF can learn the same prefix via multiple paths; this is normal. The router selects the best path based on metric, and the other paths are kept in the routing table as backup or for equal-cost load balancing if metrics are equal.

This option is incorrect because OSPF’s default administrative distance (110) is higher than EIGRP’s (90), making OSPF routes less preferred when both advertise the same prefix.

This option is incorrect because equal prefix length does not cause routers to install both routes equally; administrative distance determines which route is preferred and installed.

This option is incorrect because routers can receive and compare the same prefix from multiple routing protocols; they do not reject prefixes simply because they come from different sources.

This option is incorrect because passive interfaces do not convert OSPF routes into static routes; OSPF routing remains dynamic and active elsewhere.

This option is incorrect because the passive-interface command does not affect the router ID selection, which is determined by other OSPF rules.

This option is incorrect because passive-interface affects only the specified interface unless configured globally; it does not disable OSPF on all interfaces.

The OSPF router ID is determined by the highest IP address on a loopback interface or the highest active physical interface IP at the time of OSPF process startup, not by passive-interface configuration. A passive interface does not influence router ID selection.

The passive-interface command only suppresses OSPF hello packets on that specific interface; OSPF continues to operate normally on other interfaces, forming adjacencies and exchanging routing information. It does not disable OSPF globally.

The passive-interface command is specific to OSPF and does not change the routing protocol. OSPF remains OSPF; it simply stops sending hellos on that interface. EIGRP has its own passive-interface command with similar behavior but does not convert protocols.

The specific factual error is that a floating static route must have a higher AD than the dynamic protocol to act as a backup; setting it equal or lower would disrupt the primary route.

The specific factual error is that removing OSPF is an extreme measure that breaks connectivity, whereas a floating static route is meant to be a seamless backup.

The specific factual error is that adding an extra static route is not the standard solution; Cisco recommends using the exit interface for directly connected next-hops to ensure route validity.

The specific factual error is that a reload is not required to apply MTU changes; the interface MTU is applied immediately, and the OSPF process can be cleared to re-establish adjacencies.

The specific factual error is that OSPF network type does not affect MTU requirements; MTU must match regardless of network type.

The specific factual error is that timer mismatches affect the INIT and 2-WAY states, while EXSTART is associated with MTU or database descriptor (DBD) packet issues.

The specific factual error is that the network statement for the transit link is necessary for OSPF adjacency; removing it would break the OSPF neighbor relationship.

The specific factual error is that applying passive-interface to the transit link would prevent the OSPF neighbor relationship from forming, which is not the goal.

The specific factual error is that adding a network statement does not suppress hello messages; it only includes the interface in the OSPF process.

OSPFv3 adjacency formation does not depend on hostnames; hostnames are only used for identification in show commands and have no impact on routing protocol operation.

OSPFv3 can use any valid IPv6 prefix length, including /64, /126, or /127, for the link between routers. The /64 requirement is for SLAAC, not for routing protocols.

OSPFv3 is specifically designed to run on directly connected interfaces, just like OSPFv2. It forms adjacencies over directly connected links to exchange routing information.

Duplicate router IDs cause adjacency problems but usually result in neighbor states other than INIT or generate specific error messages. INIT state more commonly indicates one-way Hello communication rather than duplicate router ID issues.

Incorrect. FULL is the final OSPF neighbor state indicating full adjacency and route exchange completion. INIT is an early state and does not mean routers are waiting to install routes.

Incorrect. The OSPF process ID is locally significant and does not affect neighbor adjacency formation. Using the same or different process IDs on routers does not cause them to remain stuck in the INIT state.

OSPF neighbor formation does not depend on hostnames; it relies on matching parameters such as area ID, authentication, hello/dead intervals, and network type. Hostnames are only used for local identification and do not affect OSPF adjacency.

OSPF can operate over any VLAN or routed interface; there is no requirement to use VLAN 1. The adjacency issue is unrelated to VLAN numbering, and OSPF works independently of VLAN assignments on routed ports.

OSPF is designed to run on routed interfaces (Layer 3 interfaces) and does not require trunking. Trunk ports are used for carrying multiple VLANs between switches, not for OSPF adjacency between routers.

Incorrect because the static route has a higher administrative distance (200) than OSPF (110), making it less preferred and preventing it from being installed while the OSPF route is available.

Incorrect because routers do not install multiple routes with different administrative distances to the same prefix simultaneously; only the route with the lowest administrative distance is installed.

Incorrect because routers can and do choose one preferred route when multiple routes to the same prefix exist; conflicting routes do not cause both to be rejected.

Incorrect. Dynamic routes do not always override static routes; route preference depends on administrative distance, not just whether a route is dynamic or static.

Incorrect. Equal destination networks do not automatically cause load balancing if the routes have different administrative distances; only routes with equal AD and metrics are load-balanced.

Incorrect. Overlapping destinations from different sources are common and do not prevent route installation; the router uses administrative distance to choose the preferred route.

The specific factual error is that 'show ip route ospf' shows only existing OSPF routes, not neighbor states. Redistribution is not needed for directly connected interfaces in the same OSPF area.

The specific factual error is that debugging is not the initial diagnostic step; it should be used after verifying neighbor states and interface parameters. Changing the router ID is unnecessary unless there is a duplicate router ID issue.

The specific factual error is that 'show ip protocols' does not display per-interface OSPF parameters. The problem is likely at the interface level, not the process level.

The specific factual error is that OSPFv3 uses interface-level commands ('ipv6 ospf area') rather than the network statement used in OSPFv2.

The specific factual error is that OSPFv3 interface configuration is required on each interface, not just globally.

The specific factual error is that 'router ospf' is for IPv4 OSPF; OSPFv3 requires 'ipv6 router ospf'.

The network statement 10.0.0.0 0.255.255.255 area 0 matches any IP in the 10.0.0.0/8 range, which likely includes the interface IP. Therefore, the network statement is not the issue.

A router-id is automatically selected from the highest loopback or physical interface IP if not manually configured. Lack of manual configuration does not prevent adjacency formation; OSPF will still function.

The running-config does not show any authentication configuration, and the symptom (no neighbors) is consistent with passive interfaces, not authentication mismatches. An authentication mismatch would typically show neighbors in EXSTART/EXCHANGE state, not missing entirely.

This option is incorrect because a higher metric indicates a less preferred path in OSPF. The route with metric 30 is less optimal than the one with metric 20 and therefore not preferred.

This option is incorrect because OSPF does not reject routes simply because their metrics differ. Differing metrics are normal and help the router choose the best path rather than causing route rejection.

This option is incorrect because the router already has specific OSPF routes to the destination. A default route is not preferred when a more specific route with a valid metric exists.

OSPFv3 uses link-local addresses, not global unicast addresses, for neighbor formation.

OSPFv3 requires explicit interface configuration under the routing process; it is not automatically enabled.

The neighbor ID shown is the Router ID, not the IPv6 address of the neighbor's interface.

Incorrect because duplicate default routes affect routing decisions but do not impact the OSPF neighbor formation process, which depends on hello packets and network type compatibility.

Incorrect since VLAN trunking applies to Layer 2 switch ports, not routed interfaces running OSPF. The problem described involves OSPF adjacency, not VLAN or trunk configuration.

Incorrect because OSPF process IDs are locally significant identifiers and do not need to match between routers for neighbor relationships to form. This does not cause adjacency failure.

Adding a global 'router ospfv3 1' command is unnecessary; OSPFv3 can be enabled directly on the interface without a separate global configuration.

Using 'show ip ospf neighbor' and 'show ip route ospf' are IPv4 OSPFv2 commands, not valid for OSPFv3 which requires 'show ospfv3 neighbor' and 'show ipv6 route ospf'.

The 'show ipv6 route' command displays all IPv6 routes, not just OSPF-learned ones; the filter 'ospf' is required to see OSPF routes specifically.

Passive-interface does not influence router-ID selection, which is based solely on highest active loopback IP address at process initialization.

Confusing DR election parameters with router-ID election leads candidates to a parameter that is irrelevant to router-ID stability.

Changing area type does not address router-ID fluctuation; it targets LSDB optimization, which is unrelated to the dynamic router-ID re-election after loopback addition.

The OSPF process ID is locally significant and does not affect which networks are advertised. Changing the process ID to 50 is unnecessary and does not solve the problem of missing routes.

OSPF can advertise directly connected LANs if their interfaces are included in the OSPF network statements. This option is incorrect because directly connected LANs are advertised when properly configured.

A default route is not required for a router to learn intra-area OSPF routes. OSPF routers exchange routing information through link-state advertisements without needing a default route first.

The OSPF 10.1.1.0/24 route matches the destination IP but has a shorter prefix length than the static /25 route. Since longest-prefix match takes priority, this route is not used.

The default route is a last-resort route used only when no other specific routes match the destination IP. Since more specific routes exist, it is not selected here.

The router does not load-balance across routes with different prefix lengths because longest-prefix match selects a single best route, so this option is incorrect.

A standard static route with the default administrative distance of 1 would override the OSPF route (AD 110) because a lower AD is preferred. This would replace the primary OSPF path with the static route, not provide a backup that only activates upon failure.

Removing OSPF entirely eliminates the primary dynamic routing protocol, which is not a backup solution. The question requires preserving OSPF as the normal path and only providing an automatic backup when OSPF fails.

Disabling the routing table is not a valid operational practice; routers require the routing table to forward packets. This option does not provide any automatic backup mechanism and would break connectivity entirely.

This option is incorrect because dynamic routes like OSPF are not automatically preferred over static routes. Administrative distance determines preference, and static routes have a lower AD than OSPF by default.

This option is incorrect because having the same prefix length does not mean both routes are installed. The router uses administrative distance to choose a single best route.

This option is incorrect because a normal static default route is valid and installed immediately. A floating static route is only needed if you want a backup route with a higher AD.

Area ID identifies OSPF areas, which are logical subdivisions within the OSPF domain, but it does not uniquely identify individual routers. Selecting area ID confuses the concept of router identification with area grouping.

Hello timer controls how often OSPF routers send hello packets to maintain neighbor adjacency. It does not serve as a unique identifier for routers.

Wildcard mask is used in OSPF network statements to specify which IP addresses belong to an OSPF area. It does not identify routers uniquely.

The specific factual error is that the permit statement does not exclude ports 80 and 443. It allows all TCP ports, which is too permissive.

The specific factual error is that the permit statements allow the very ports that should be denied for VLAN 20. This misinterprets the requirement.

The specific factual error is that the permit statement is too broad and overrides the deny statements. The correct approach is to permit only non-HTTP/HTTPS ports, not all ports.

Incorrect because OSPF does not always override static routes. Administrative distance matters only when prefix lengths are equal, and longest-prefix match takes precedence over route source.

Incorrect because the static route does not have an administrative distance of 255; it is valid and installed in the routing table. The issue is the static route’s broader prefix, not its administrative distance.

Incorrect because the destination IP 198.51.100.70 falls within both the /24 static route and the /26 OSPF route. The router chooses based on prefix specificity, not exclusion from the routes.

Option B is incorrect because RIP routes can still be installed in the routing table even when OSPF is running; the router does not automatically suppress RIP routes.

Option C is wrong because both OSPF and RIP routes shown have the same prefix length (/16), so prefix length does not influence the choice here.

Option D is incorrect because cross-protocol route selection is based on administrative distance, not metric comparison; RIP's metric being lower does not make it preferred over OSPF.