CCNA Show IP Route 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.

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.

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.

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 specific factual error is that an AD of 1 does not create a floating static route; it matches the primary route's AD, so both routes are used.

The specific factual error is that AD 0 is used for directly connected routes; using it for a static route would override the primary route.

The specific factual error is that AD 255 means the route is not trusted and will not be installed; it cannot serve as a backup.

The AD must be greater than 90 to ensure the static route is only used when EIGRP fails. An AD of 90 does not create a floating static route.

A floating static route must have a higher AD than the primary route. An AD of 85 is lower than 90, so it would be preferred over EIGRP.

The default AD for static routes is 1, which is lower than EIGRP's 90. Without specifying a higher AD, the static route will be preferred and not act as a floating static route.

Static routes are not permanent; they are removed from the routing table if the next-hop interface goes down or the next-hop IP becomes unreachable, because the route is no longer valid.

A static route does not automatically change into a default route; default routes are explicitly configured (e.g., ip route 0.0.0.0 0.0.0.0 next-hop) and are not derived from other static routes.

A static route does not become an OSPF external route automatically; OSPF routes are learned through the OSPF protocol, and a static route remains static unless redistributed into OSPF via configuration.

The IPv6 static route should use a fully specified next-hop (IPv6 address) rather than just an exit interface to avoid recursive routing failures.

Floating static routes require a higher administrative distance (e.g., 200) so they are only used when the primary route is unavailable.

A fully specified IPv6 static route includes both the exit interface and the next-hop IPv6 address to ensure proper routing.

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.

The default route is incorrect because it is the least specific route and only used when no other matching routes exist; here, more specific routes are available.

The OSPF route to 10.1.1.0/24 is less specific than the /25 static route, so it is not selected despite matching the destination IP address.

The OSPF route to 10.1.0.0/16 is the least specific among the options and will not be chosen when more specific routes like /24 or /25 exist.

The specific factual error is that the default route configuration is correct as given; there is no need to modify it. Changing the AD of the default route could cause routing issues.

The specific factual error is swapping the administrative distances: the primary route should have a lower AD than the floating route. Here, the primary route has AD 150 and the floating route has AD 1, causing the backup to be preferred.

The specific factual error is that static routes without an AD default to 1, so both routes would have equal AD. The floating route must have a higher AD (e.g., 150) to act as a backup.

The specific factual error: An administrative distance of 255 is reserved for routes that are not considered valid; they are not installed in the routing table.

The specific factual error: The permanent keyword forces the route to stay in the routing table regardless of reachability, which is the opposite of what is needed.

The specific factual error: The AD values determine route preference; swapping them changes which route is preferred but does not address the removal of the route when the next-hop is unreachable.

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.

A default gateway is needed only for management traffic from the switch itself, not for DNS forwarding; the switch already communicates with the router via its default route.

A static default route is already present and unrelated to DNS resolution; adding another route would not solve the name resolution failure.

The 'ip domain-lookup' command only enables the DNS client on the switch itself, not DNS forwarding for clients like PC1.

The routing table shows a static route to 10.10.20.0/24 via 10.10.10.2, so the route is present. The issue is not a missing route.

The interface is shown as directly connected with a local address, indicating it is up and operational. An administratively down interface would show 'administratively down' in the status.

The output shows 'Gateway of last resort is 10.10.10.2 to network 0.0.0.0', confirming the default route is configured.

The administrative distance should be higher than the primary route's AD (1) to make it less preferred. Setting it to 1 makes it equal, not a backup.

The question explicitly states 'with an administrative distance of 150'. Using 250 is not what was asked, though it would be technically valid.

The default AD is 1, which equals the primary route's AD. This does not create a floating route; both routes are equally preferred.

This option is incorrect because metrics such as OSPF cost and RIP hop count are not compared across different routing protocols. Administrative distance is the primary factor in route selection between protocols.

This option is incorrect because the dynamic nature of BGP does not override the administrative distance rule. Static routes with AD 1 are always preferred over eBGP routes with AD 20.

This option is incorrect because simplicity of metric calculation (hop count) does not influence route preference. Administrative distance is the deciding factor, and RIP’s higher AD (120) makes it less preferred than OSPF (110).

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.

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.

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.

This option revisits a step already completed and verified, making it redundant. Candidates might think double-checking routing is safe, but the scenario explicitly states routing is working as expected.

Some candidates might believe inter-VLAN communication requires a default route, but directly connected routes already provide full reachability without static routing. This action is overly drastic and misdirected.

Candidates often jump to VLAN misconfigurations when inter-VLAN communication fails, even when routing is confirmed. The scenario already establishes the VLAN 20 host's location; the next logical layer to inspect is ARP resolution.

Option A is incorrect because EIGRP-learned routes are marked with 'D' in Cisco IOS routing tables, not 'C'. The letter 'D' stands for 'Dynamically learned' via EIGRP, so 'C' cannot represent EIGRP routes.

Option C is incorrect because candidate default routes are not indicated by 'C'. Cisco uses 'S*' or other notations for candidate default routes, so 'C' does not represent default routes.

Option D is incorrect because static routes use the code 'S' in Cisco routing tables. The code 'C' never represents static routes, so this option is invalid.

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 10.1.0.0/16 route is less specific than the 10.1.10.0/24 route. Although it matches the destination IP, the router prefers the more specific /24 prefix, so this option is incorrect.

The 0.0.0.0/0 default route is only used when no other specific route matches the destination. Since both /16 and /24 routes match, the default route is not chosen here, so this option is incorrect.

Overlapping routes like 10.1.0.0/16 and 10.1.10.0/24 are common and do not prevent routing. The router resolves overlaps by selecting the longest prefix, so this option is incorrect.

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.

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.

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.

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.

This option is incorrect because the next-hop IP address does not influence route preference. Cisco routers do not consider the numeric value of the next-hop IP when selecting routes.

This option is incorrect because the router does not prefer routes based on the order they were configured. Route selection depends on administrative distance and metrics, not configuration sequence.

This option is incorrect because route names or descriptions are only for human readability and do not enforce policy-based routing. Policy-based routing requires explicit configuration beyond naming.

Replacing the Ethernet cable between R1 and R2 is unnecessary because R1 can already ping 10.1.23.2, indicating that the physical link and Layer 3 connectivity to the next-hop router are functioning correctly.

Changing the OSPF router ID on R1 is irrelevant here because the problem is not related to router ID conflicts or OSPF neighbor relationships but to missing route advertisements for the remote LAN.

Disabling CEF (Cisco Express Forwarding) will not help because CEF does not prevent routes from being learned or advertised; it only affects packet forwarding efficiency, so this option does not address the root cause.

The specific factual error: Administrative distance determines route preference; a lower AD is preferred. Setting the backup to AD 1 would make it the primary route, not a backup.

The specific factual error: The 'permanent' keyword prevents route removal when the interface goes down, which is not the solution here. The backup route needs to become active when the primary fails, not be forced to stay.

The specific factual error: The track command is used to conditionally remove a static route based on reachability, but it is not necessary if the primary route is correctly configured without 'permanent'. The existing backup route should work once the primary route is removed.

The router selects the route with the lower administrative distance, not higher. Administrative distance is a measure of trustworthiness; a lower value indicates a more reliable source. For example, a static route (AD 1) is preferred over an OSPF route (AD 110).

Directly connected routes have an administrative distance of 0, not 1. An AD of 0 is the most trustworthy and cannot be overridden by any dynamic route. The value 1 is used for static routes.

Directly connected routes have an AD of 0, which is lower than any dynamic routing protocol (e.g., OSPF AD 110, EIGRP AD 90). Therefore, directly connected routes are always preferred over dynamic routes, not the other way around.

This reflects a common misunderstanding that AD is the sole tie-breaker between routes from different sources, ignoring prefix length priority.

Candidates might assume that if the OSPF route is not used, it must be inactive; however, the exhibit does not show this.

Candidates may mistake metric for the primary selection criterion, not realizing prefix length dominates all other route comparison steps.

Incorrect. Static default routes can coexist with OSPF routes. The router uses administrative distance to determine which route to install, so static routes are not automatically ignored when OSPF is enabled.

Incorrect. A default route must use the destination 0.0.0.0 with a mask of 0.0.0.0. Using a /24 mask is invalid for a default route and would not solve the issue of route selection.

Incorrect. Floating static routes do not require the next hop to be a loopback address. The next hop can be any reachable IP address, so this is not the reason the route is not installed.

A lower AD would make it preferred, defeating the purpose of a floating route.

The primary route is removed from the table when the interface goes down.

Track objects are optional enhancements for faster failover but not mandatory for floating static operation.

Believing that a static route is removed from the routing table when a better route exists, rather than understanding it remains but is inactive.

Assuming that a static route's next-hop must be directly attached, ignoring that recursive routing via another routing protocol or static route is allowed.

Thinking that recursive static routes are prone to loop suppression, rather than understanding that the route is simply withdrawn when the next-hop is no longer reachable.

The specific factual error is that an AD of 90 does not make the static route less preferred than EIGRP; it creates equal preference.

The specific factual error is that a lower AD makes the route more preferred, so the static route would override EIGRP.

The specific factual error is that AD 255 means the route is not trusted and is effectively ignored.

The specific factual error is that an administratively down interface results in a hard failure, not intermittent connectivity.

The specific factual error is that a complete ARP entry indicates no Layer 2 problem, contradicting the symptom of intermittent connectivity.

The specific factual error is that a missing route results in consistent unreachability, not intermittent problems.

The static default route has an administrative distance of 200, which is higher than OSPF's default distance of 110. Therefore, OSPF's route is preferred, and the static route does not override it. Manual configuration does not bypass administrative distance; the router always prefers the lower distance.

Load balancing requires multiple routes with equal administrative distance and metric. Here, OSPF and the static route have different administrative distances (110 vs. 200), so they are not equal. The router will only use the best route (OSPF) and not load-balance.

Overlapping default routes are common and do not cause the router to ignore them. The router uses the route with the lowest administrative distance (OSPF) and ignores the static route unless OSPF fails. There is no conflict that would cause both to be ignored.

The router does not discard the OSPF route; it installs both /16 and /24 entries because they represent different network-specific entries.

The traffic matches the /24 route, not the /16, so it would be forwarded via the EIGRP next-hop.

The /24 is a subset; traffic outside 172.16.10.0/24 matches only the /16 OSPF route.

When the next-hop IP is not directly connected, the router does recursively resolve the address to determine the outgoing interface.

The specific factual error: EIGRP does not use 'network 0.0.0.0' to advertise a default route; default routes are typically redistributed or generated via 'ip default-network' or redistribution. Removing the EIGRP default route would break the intended primary path.

The specific factual error: Administrative distance is the primary factor for route selection between different routing protocols or sources. Changing the EIGRP metric does not affect the comparison with a static route.

The specific factual error: The 'ip route' command syntax is 'ip route prefix mask {next-hop | interface} [distance] [name] [permanent] [tag tag]'. There is no metric parameter. The correct way to make a static route less preferred is to set a higher administrative distance.

This option is incorrect because metric values are only compared among routes learned from the same routing protocol. The OSPF metric of 30 is irrelevant when compared to a static route, which is a different routing source with a lower administrative distance.

This option is incorrect because routers do not install multiple routes to the same prefix from different routing protocols unless they have equal administrative distance and are configured for load balancing. Here, the static route’s lower AD prevents the OSPF route from being installed.

This option is incorrect because the router does not delay route installation until a full SPF recalculation. Route selection is immediate based on administrative distance and metric rules. SPF recalculation only affects OSPF route selection, not cross-protocol comparisons.

Candidates often assume OSPF is not working at all when a default route is missing, ignoring other OSPF routes in the table.

Candidates may assume any connectivity failure means an interface is disabled, but the routing table would show no connected network if the interface were shut down.

Candidates might think a misconfigured static route would cause the problem, but they overlook that the route would still appear in the table, just with a different next-hop.

This option is incorrect because the active route is determined by the administrative distance, not the metric. In this case, the EIGRP route has a lower administrative distance than the OSPF route, making it the active route.

This option is incorrect because only one route can be active for a given destination in a routing table, and having identical prefixes does not mean both routes can be active simultaneously. The router will select the route with the lower administrative distance, which is not addressed here.

This option is wrong because both routes are valid, and the router will select the route with the lower administrative distance, not the metric. The administrative distance of the EIGRP route is lower than that of the OSPF route, making it the active route.

This option is incorrect because Cisco routers do not install multiple default routes with different administrative distances simultaneously; only the route with the lowest AD is installed and used.

This option is incorrect because the backup route is not ignored permanently; it becomes active when the primary default route toward ISP-A fails, ensuring continuous connectivity.

The specific factual error is that OSPFv3 uses interface-level configuration, not network statements under the OSPF process.

The specific factual error is that setting a router ID alone does not activate OSPFv3 on an interface; OSPFv3 must be explicitly enabled on the interface.

The specific factual error is that 'passive-interface default' would actually prevent adjacency, not help form it.

Administrative distance is only compared when two routes have the same prefix length. Here, the /32 route has a longer prefix, so it is chosen first.

Load balancing requires routes with identical prefix lengths and metrics. The /32 and /24 routes are treated as different destinations.

AD is only compared when routes have the exact same prefix length. The routing table can hold multiple overlapping routes as long as they differ in prefix length.

Misunderstanding of route preference: a higher AD value does not keep a floating static installed when a better OSPF route becomes available.

Troubleshooting should follow the OSI model bottom‑up; immediately resetting processes skips basic interface‑level verification.

It targets a different root cause (OSPF adjacency failure due to MTU) that would manifest constantly, not only after interface recovery.

The question says R3 advertises the network via OSPF; a missing network command would contradict that, so the failure must be in adjacency formation.

The presence of other OSPF routes on the same interface disproves a blanket multicast ACL; the issue is specific to R3’s adjacency.

A duplicate router ID could prevent adjacency, but the scenario’s focus on passive-interface default provides a more common and direct cause for a total lack of adjacency when OSPF is correctly configured on the network.

Candidates may misinterpret a failed ping as indicating no default route exists, overlooking that the route is present but unusable.

Candidates may think a higher AD is blocking the route, but the AD is standard and not the issue.

A common troubleshooting step is to verify ip routing, but the exhibit clearly shows an active routing table.

The specific factual error: The incorrect static route remains in the routing table, causing recursive routing failure. The router will still try to resolve the next-hop 10.0.0.1, which is its own interface, leading to a loop.

The specific factual error: The route does not have an administrative distance of 10, and using an exit interface instead of a next-hop IP is not the intended configuration. Also, the route would be installed with default AD 1, not 10.

The specific factual error is using an incorrect subnet mask and omitting the next-hop IP in the directly connected static route. The mask should match the point-to-point link (typically /30 or /31), and the next-hop must be specified to ensure the route is directly connected.

The specific factual error is using a /32 mask instead of the subnet mask of the link. A /32 route to the next-hop IP is a valid workaround but is not the standard practice; the question expects a directly connected route to the network containing the next-hop, not a host route.

The specific factual error is using the floating route's next-hop as the next-hop for the directly connected route. The directly connected route must be to the network containing 192.0.2.2, not to the backup next-hop.

This option is wrong because the OSPF route to 10.60.4.0/24 does not directly match the destination 10.60.4.17, which falls under the static route to 10.60.4.16/28. OSPF would not be preferred if a more specific static route exists.

The EIGRP route to 10.60.0.0/16 is not used for the destination 10.60.4.17 because it does not match the more specific subnet of 10.60.4.16/28, which is preferred in routing decisions.

This option is wrong because there is a valid static route to the destination 10.60.4.17 via the static route to 10.60.4.16/28, making it reachable. Therefore, stating 'no route at all' is incorrect in this context.

Setting the floating route AD to 1 makes it equal to the primary route's AD, defeating the purpose of a floating static route.

The primary route must have a lower AD than the floating route to be preferred. Setting it to 200 makes it equal to the backup, causing ambiguity.

The question states 'IPv4 and IPv6 static routes, default routes' and specifies an IPv6 next-hop. Ignoring IPv6 is a direct violation of the requirements.

Candidates often assume that a route pointing to an interface requires that interface to be up, but Null0 is always available.

A misconception that the default route is special and cannot be used with Null0, but any valid IP prefix can be directed to Null0 to create a discard route.

Confusing Null0 routes with Ethernet interface routes, which require a next hop, leads to the incorrect belief that a next hop is mandatory for all static routes.

Swapping the ADs would keep the backup route preferred, failing to make the primary path active when available.

The OSPF route to 10.30.5.0/24 is less specific than the /25 static route, so the router prefers the longest mask.

The default route (0.0.0.0/0) has the shortest prefix length and would be used only if no other route matches.

10.30.5.130 is inside the 10.30.5.128/25 subnet range, meaning a route exists for this destination.

Incorrect. A high administrative distance does not make a route override dynamic routes; it makes the route less preferred. Therefore, the static route will not immediately override dynamic routes.

Incorrect. Assigning a high administrative distance does not disable the route; it remains configured and available as a backup. The route is not conceptually disabled but deprioritized.

Incorrect. Administrative distance affects route preference, not the route prefix or mask. Changing AD does not convert a default route into a host route.