Show IP Route Output Practice Questions

The static route for 10.10.20.0/24 is missing from the routing table.

Why wrong: The routing table entry for 10.10.20.0/24 is visible in the output, showing 'via 10.10.10.2', so the static route is certainly not missing. This option misreads the table; the missing entry is actually the default route (0.0.0.0/0), not the static route to the 10.10.20.0 network. The presence of this specific static route does not affect the default route's reachability, which is the real issue.

The GigabitEthernet0/0 interface is administratively down.

Why wrong: The interface status in the exhibit is 'up/up' with IP address 10.10.10.1, and the connected route for 10.10.10.0/24 is present in the routing table. An administratively down interface would be 'shutdown' and would remove all connected routes, including the subnet that contains the next-hop. Since the next-hop is unreachable despite the interface being up, the problem lies with the remote router or Layer 2 connectivity, not the local interface state.

The default route is not configured; the gateway of last resort is missing.

Why wrong: The output includes the line 'Gateway of last resort is 10.10.10.2 to network 0.0.0.0', proving that a default route is configured and the router recognizes it as the gateway of last resort. However, the default route does not appear as an 'S*' entry in the routing table because the next-hop is unreachable. This option incorrectly assumes that the configuration is missing; in reality, the route is configured but not installed.

The static route overrides OSPF immediately because static routes always win.

Why wrong: Static routes do not 'always win' because route selection is based on administrative distance, not on the route type alone. By default, a static route has an AD of 1, which normally beats OSPF's 110, but here the static route's AD has been configured higher than OSPF's, allowing OSPF to remain preferred. Therefore, it is the specific numeric AD values that determine preference, not a blanket rule that static outranks dynamic routing.

Both routes must be installed simultaneously because they point to the same destination.

Why wrong: The router does not install both routes just because they point to the same destination; it installs only the one with the best (lowest) administrative distance for that prefix. Both routes would be installed only if they had equal AD and formed equal-cost multipath (ECMP), or if they addressed different prefixes. Since the same destination and differing ADs mean only OSPF is selected, simultaneous installation is not required.

The router removes the OSPF route because the static route has a manually configured distance.

Why wrong: A manually configured distance does not cause the router to remove the OSPF route. The router selects the route with the lowest AD for the destination; because the static route's manually configured distance is higher than OSPF's 110, OSPF remains the best route and stays in the routing table. The static route is simply not installed, and OSPF is not removed merely because a static route with a higher distance exists.

The OSPF route is installed because cost 20 is lower than metric 0

Why wrong: This statement incorrectly compares OSPF's cost (20) to the static route's metric (0) and assumes a lower number wins. In Cisco IOS, a router first compares administrative distance when multiple routing sources provide a path to the same network; only if AD values are equal are metrics compared. Since the static route's AD of 5 is much lower than OSPF's default AD of 110, the static route is installed into the routing table despite OSPF having a lower metric value. The OSPF cost is irrelevant until the static route is removed, at which point OSPF becomes the active route by default, not because its cost is lower.

Both routes are installed as equal-cost paths automatically

Why wrong: Equal-cost multipath (ECMP) only applies when multiple routes to the same prefix have the same administrative distance and the same metric, and they are usually from the same routing protocol. Here the static route has an AD of 5 while OSPF has an AD of 110, so they are not equal from the router's perspective. Moreover, their metrics—0 for the static and 20 for OSPF—are not comparable across different protocols. Therefore, the router does not install both; it selects only the static route as the single best path.

The path with the higher OSPF metric

Why wrong: Selecting the path with the higher OSPF metric would contradict OSPF's SPF calculation, which always chooses the least-cost path to a destination. A higher cost indicates a less desirable route, such as one traversing slower or more numerous links, and OSPF will never prefer it over a lower-cost alternative for the same prefix. The only time a higher-metric path is used is if the lower-metric path is absent from the routing table.

Both paths equally, because the administrative distance is the same

Why wrong: Administrative distance is a Cisco-specific trust rating assigned to the routing protocol as a whole, not a per-path metric for selecting among OSPF routes. When two OSPF paths to the same prefix have unequal metrics, the router compares the OSPF cost values directly, and the lower-cost path wins. Equal AD only means both routes are equally trusted as OSPF-learned; it does not enable load balancing, which would require the OSPF metrics to be exactly equal.

Neither path, because two OSPF routes to the same prefix are invalid

Why wrong: OSPF is fully capable of learning the same prefix through multiple paths, as occurs in redundant OSPF networks where the SPF algorithm evaluates all available routes. Having two OSPF routes to 10.10.10.0/24 is not invalid; rather, OSPF processes them and selects the one with the lowest metric for installation in the routing table, while potentially keeping equal-cost paths for ECMP. Discarding both routes would leave the network without a route, which OSPF would never do if any path exists.

The OSPF route, because dynamic routes always beat static routes

Why wrong: Dynamic routes do not automatically outrank static routes; that belief ignores how administrative distance works. Route preference is determined solely by the numeric administrative distance, not by whether the route was learned dynamically or configured manually. In this scenario, the static route's distance of 90 is lower than OSPF's 110, so the static route is more trusted. Therefore, OSPF is not installed because dynamic learning does not confer an inherent advantage.

Both routes equally, because the prefix is identical

Why wrong: Having the same prefix length does not mean both routes are equally preferred, because routes from different protocols are compared using administrative distance. OSPF's default administrative distance is 110, while this static route has a distance of 90. The router does not aggregate or load-balance across protocols; it installs only the route with the lower administrative distance. Thus the identical prefix length has no bearing on equality when the administrative distances differ.

Neither route, because duplicate information is dropped

Why wrong: Routers do not simply drop duplicate routing information; they perform a route-selection process. For the same destination prefix, the router compares administrative distances across different sources and installs the winning route in the forwarding table. The losing route remains in the originating protocol's database, not in the routing table. Therefore, duplicate information is not dropped; it is evaluated and only the best route is chosen.

Remove the incorrect static route 192.0.2.0 255.255.255.0 10.0.0.1 and add ip route 192.0.2.0 255.255.255.0 10.0.0.2 1

Why wrong: This is incorrect because the administrative distance of 1 is lower than the directly connected route's AD of 0, so the floating static route would be preferred over the directly connected route, defeating its purpose as a backup.

Keep the existing static route and add ip route 192.0.2.0 255.255.255.0 10.0.0.2 10

Why wrong: The existing static route cannot remain because it uses 10.0.0.1 — R1's own G0/0 address — as the next hop for the remote 192.0.2.0/24 network. When R1 processes this route, it performs a recursive lookup for 10.0.0.1 and finds itself, causing packets to be looped back out the same interface instead of being forwarded to R2; this route becomes the active route with AD 1, outcompeting the new AD 10 route. Adding the floating static route with next-hop 10.0.0.2 does not remove or override the bad route—the lower-AD bad route remains preferred, so traffic to 192.0.2.0/24 is still black-holed. You must delete the faulty static route first, then add the correct floating route with AD 10.

Remove the incorrect static route 192.0.2.0 255.255.255.0 10.0.0.1 and add ip route 192.0.2.0 255.255.255.0 g0/0

Why wrong: This is incorrect because using an exit interface (g0/0) instead of a next-hop IP address for a static route to a remote network can cause issues if the interface goes down, but more importantly, the question requires a floating static route with AD 10, which is not provided here. Additionally, the route would be directly connected? Actually, using an exit interface makes the route a directly connected static route, which has AD 0? No, static routes with exit interface have AD 1 by default. But the question specifies a floating static route with AD 10, so this does not meet the requirement.

The OSPF route because metric 20 is lower than 30720

Why wrong: Comparing OSPF's metric of 20 to EIGRP's feasible distance of 30720 is invalid because each routing protocol uses a completely different metric calculation. OSPF calculates cost from interface bandwidth, whereas EIGRP uses a composite formula based on bandwidth and delay, so these numbers are not directly comparable. The router does not attempt to compare metrics across protocols; it first selects the route with the lowest administrative distance. Since EIGRP's AD of 90 is lower than OSPF's 110, the metric values are irrelevant to the final decision.

Both routes because ECMP is automatic across different protocols

Why wrong: Equal-cost multipath (ECMP) only applies when multiple routes have the same metric and are learned from the same routing protocol. Here, OSPF and EIGRP are different protocols with different administrative distances, so the router will not consider them for load balancing. Only the single route with the lowest AD is installed in the routing table, and traffic is forwarded along that one path. ECMP cannot occur across different protocols because they are not evaluated on an equal footing.

Neither route until one is redistributed into the other protocol

Why wrong: Redistribution is not required for a router to install a route learned via OSPF or EIGRP; each protocol independently builds its IP routing table and selects its best route. Redistribution is only used when injecting routes from one routing protocol into another for downstream routers, but it has no bearing on which of the two current routes is chosen for this router. The router simply compares the administrative distance of the two protocols and installs the one with the lower AD. Therefore, route installation and redistribution are separate processes.

The static route because static routes always win over dynamic routes

Why wrong: A static route does not automatically override a dynamic route. The router compares administrative distance, and the default static route AD is 1, but a floating static route is deliberately set with a higher AD (e.g., 130) so that it yields to a more preferred dynamic route like OSPF (AD 110). Static routes only win when their AD is lower than the competing route's AD.

Both routes because the prefix length matches

Why wrong: Even when two routes share the same prefix length, the router installs only the single best route in the routing table. Route selection depends primarily on administrative distance, not just the subnet mask. Since the OSPF route has a lower AD than the floating static route, the router ignores the static route for this prefix and does not install both; both routes would be installed only if they had the same AD and metric.

Neither route until equal-cost load balancing is configured

Why wrong: Equal-cost load balancing requires two or more routes to the same destination with identical administrative distance and identical metric. Here the OSPF route and the floating static route have different ADs (110 vs. 130), so they are not equal-cost candidates. The router does not wait for load balancing to be configured; it immediately selects the OSPF route as the best path.

The OSPF 10.1.1.0/24 route

Why wrong: The OSPF route 10.1.1.0/24 does match the destination, but it describes a broader range of 256 addresses, whereas the static 10.1.1.128/25 describes a narrower range of 128 addresses that still includes the target. Longest-prefix match dictates that the more specific /25 route is preferred over the /24, regardless of the administrative distance or protocol; therefore, the OSPF route is not the one that gets used.

The default route

Why wrong: A default route is the ultimate prefix-length of 0.0.0.0/0, the least specific of all possible routes. In the routing table, it is used only when no other route matches the destination; because the /25 and /24 routes both match 10.1.1.130, the default route is never consulted, and even if it were, the /25's longer prefix would still take precedence.

The router load-balances across all three

Why wrong: Load balancing across equal-cost paths only applies to multiple routes that share the exact same prefix length and destination network. Here, the three candidates are 10.1.1.0/24, 10.1.1.128/25, and 0.0.0.0/0, each with a different prefix length, so they are not competing equal-cost routes; longest-prefix match selects exactly one route, so the router does not distribute the packet across them.

ip default-gateway 203.0.113.1

Why wrong: The command "ip default-gateway 203.0.113.1" is used on Layer 2 switches or when IP routing is disabled on a router. It configures the management interface's default gateway so that management traffic (e.g., Telnet, SNMP) can leave the device. It does not install a default route in the routing table, so it cannot forward transit traffic when Cisco IOS routing is enabled.

default-information originate 203.0.113.1

Why wrong: "default-information originate 203.0.113.1" is not used to create a static route. This command is issued within a routing protocol (e.g., OSPF) configuration mode to force the router to advertise a default route into the routing domain. It does not accept a next-hop address as an argument, and on its own it cannot insert a default static route into the local routing table.

route add 0.0.0.0 203.0.113.1

Why wrong: "route add 0.0.0.0 203.0.113.1" is not a valid Cisco IOS command. It resembles the Windows 'route' or Unix 'route add' utility syntax, which is used in operating systems, not on Cisco routers. In Cisco IOS, the mandatory prefix and mask parameters must be explicitly entered; there is no abbreviated form that omits the mask or uses this syntax.

Because static routes cannot reference exit interfaces.

Why wrong: Static routes may legitimately reference an exit interface, such as ip route 10.200.0.0 255.255.0.0 GigabitEthernet0/0, which is a common and valid configuration for point-to-point links. The problem in the exhibit is not that the configuration uses an exit interface, but that the referenced interface has been administratively shut down. When the interface is down, the route is removed from the routing table, whereas a healthy interface would allow the static route to appear.

Because the destination must be a /24, not a /16.

Why wrong: The prefix length /16 is perfectly valid for a static route, and there is no Cisco IOS requirement that a destination be a /24. Static routes accept any legitimate IPv4 prefix, and subnetted networks can be summarized into larger blocks like /16. The exhibit shows the route missing because the outgoing interface is down, not because the mask is too short or unsupported.

Because static routes require NTP before installation.

Why wrong: Network Time Protocol (NTP) is used for clock synchronization and does not affect the Routing Information Base or the installation of static routes. A static route is evaluated based on the administrative distance, metric, and the reachability of the configured next hop or exit interface, not on any time-based condition. NTP misconfiguration could impact logging or certificate validation but will never prevent a valid static route from being installed.

If two routes have the same prefix length, the route with the higher administrative distance is preferred.

Why wrong: This statement is the literal opposite of the correct behavior: when two routes share the same prefix length, the router uses administrative distance as a tie-breaker, and the lower AD value is preferred. A higher administrative distance indicates a less trustworthy route, so it will never win against a lower-AD route if both are in the routing table. For instance, an OSPF route with AD 110 beats a RIP route with AD 120 for the same /24 network because 110 is lower.

The metric is used to compare routes from different routing protocols.

Why wrong: Metrics are only comparable within a single routing protocol; each protocol uses its own metric (OSPF cost, EIGRP composite, RIP hop count) and these values are not interchangeable. When a router receives routes to the same destination from different protocols, it first compares administrative distance, not metric, because AD is designed to express the trustworthiness of the route's source. After a single protocol is chosen, the metric then selects the best route from that protocol's candidates. Therefore, saying the metric is used to compare routes from different routing protocols confuses the two distinct selection phases.

A static route configured with an administrative distance of 200 will be preferred over an OSPF route with AD 110 for the same network.

Why wrong: A static route with a configured administrative distance of 200 is a floating static route; it is not installed as long as any usable route with a lower AD exists. OSPF's default AD of 110 is lower than 200, so the OSPF route is preferred for the same network and the static route remains in the backup state. This technique is useful for providing a backup path, but in this scenario the OSPF route wins the comparison because a router always selects the route with the lower administrative distance when prefix lengths match.

1. Compare administrative distance of all routes 2. Compare metric of routes with lowest AD 3. Perform longest prefix match on remaining routes 4. Forward packet using the best route

Why wrong: This sequence incorrectly starts with administrative distance. A router never compares AD across all routes in the routing table; it first performs a longest prefix match on the destination IP to find the most specific route(s). The prefix length is the primary selection criterion, and only when two or more routes share the same prefix length does AD come into play to choose the protocol with lower distance. Placing AD first would, for example, incorrectly prefer a static default route over an OSPF route to a more specific subnet, which is the opposite of real behavior.

1. Compare metric of all routes 2. Compare administrative distance of routes with lowest metric 3. Perform longest prefix match on remaining routes 4. Forward packet using the best route

Why wrong: This order is flawed because metric is never the first criterion. Metric is a protocol-specific measure (e.g., OSPF cost vs. EIGRP composite metric), and comparing metrics from different protocols is meaningless—a low metric in one protocol does not indicate it should beat a route from another protocol. Also, longest prefix match must be performed first, and only among routes with the same prefix length is AD compared first; metric is the final tiebreaker and is only compared when AD is equal, not before it.

1. Perform longest prefix match on destination IP address 2. If multiple routes match, compare metric 3. If metric is equal, compare administrative distance 4. Forward packet using the best route

Why wrong: This sequence correctly starts with longest prefix match but then swaps the tiebreaker order. After determining the most specific matching route(s), the router compares administrative distance (AD) first; only if AD is equal is the metric considered. Metric is a within-protocol preference, while AD is a cross-protocol trust value. Placing metric before AD could allow a high-AD route (e.g., EIGRP external at 170) to be chosen over a low-AD route (e.g., OSPF at 110) solely because its metric is numerically smaller, which is wrong because the router first needs to decide which routing protocol is more trustworthy.

Change the AD of the static route via 192.0.2.2 to 200 and the AD of the route via 198.51.100.2 to 1.

Why wrong: This is incorrect because it suggests modifying both routes, but the primary route already has AD 1 (default) and the backup has AD 1 as well; the fix is to increase the backup's AD, not change the primary's.

Add a static route to 192.168.10.0/24 via 192.0.2.2 with AD 1 and remove the existing route via 198.51.100.2.

Why wrong: Simply adding a primary static route via 192.0.2.2 with AD 1 and removing the existing 198.51.100.2 route eliminates all redundancy. If the 192.0.2.2 next-hop fails, there is no backup route to 192.168.10.0/24, so traffic is dropped instead of automatically failing over. The requirement explicitly calls for automatic failover, which necessitates keeping a backup path with a higher AD. Removing the backup route defeats the entire purpose of floating static routes, making this option incorrect.

Configure a policy-based route to prefer the next-hop 192.0.2.2 for traffic to 192.168.10.0/24.

Why wrong: Policy-based routing (PBR) is designed to steer traffic based on complex conditions like source addresses, packet sizes, or application protocols, not for simple primary/backup path selection. In contrast, floating static routes with differing AD values are the intended, low-overhead mechanism for basic failover to a single destination prefix. PBR would also require route-map and next-hop configuration that does not automatically track the reachability of the primary next-hop the same way as AD-based static route failover. Additionally, PBR adds CPU overhead and configuration complexity, whereas the scenario's goal is straightforward path redundancy, making static route AD manipulation the correct answer.

1. Match the destination IP address with the longest prefix in the routing table. 2. If multiple routes match, select the route with the lowest metric. 3. If still multiple routes, select the route with the lowest administrative distance.

Why wrong: Although it correctly uses longest prefix first, this sequence inverts the subsequent tie-breakers. Administrative distance is the first tie-breaker among equally specific prefixes because it indicates the protocol's trustworthiness; a route with a higher AD but lower metric would not be selected over a lower-AD route. The router only considers metric when comparing routes from the same protocol or same AD, so this ordering is impossible in practice.

1. Match the destination IP address with any prefix in the routing table (first match). 2. If multiple routes match, select the route with the lowest administrative distance. 3. If still multiple routes, select the route with the lowest metric.

Why wrong: This is incorrect because IP routing uses longest prefix match, not first match. The forwarding table is structured to select the prefix with the most network bits matching the destination, ensuring the most specific network entry takes precedence. First-match semantics are characteristic of ACLs, where entries are evaluated in order, not of routing tables. Even if AD and metric were correctly ordered, using first match could send packets toward a less specific, incorrect next hop.

1. Match the destination IP address with the longest prefix in the routing table. 2. If multiple routes match, select the route with the lowest metric. 3. If still multiple routes, select the route with the highest administrative distance.

Why wrong: This sequence makes two errors. It places metric before administrative distance, but AD is the primary tie-breaker for equally specific prefixes because it reflects the trustworthiness of the route source. Additionally, it says to select the highest AD, which is opposite of the correct behavior: a lower AD indicates a more trusted source, so it is always preferred. Therefore, this option would incorrectly favor less reliable routing information.