CCNA Show IP Route Questions — Page 2 of 2

MCQhard

A router has a static route to 10.30.5.128/25, an OSPF route to 10.30.5.0/24, and a default route 0.0.0.0/0 in its routing table. Which route will the router use for destination 10.30.5.130?

A.The static route to 10.30.5.128/25

B.The OSPF route to 10.30.5.0/24

C.The default route

D.No route, because the destination is outside all prefixes shown.

AnswerA

The router will utilise the static route to 10.30.5.128/25 because it adheres to the longest prefix match principle. This rule dictates that when multiple routes match a destination IP address, the router selects the route with the longest subnet mask, representing the most specific network. For 10.30.5.130, the /25 mask is more specific than the OSPF route's /24 mask or the default route's /0 mask, ensuring it is prioritised for forwarding.

Why this answer

The router selects the route with the longest prefix match between the destination IP and the prefixes in the routing table. 10.30.5.130 matches both 10.30.5.0/24 (prefix length 24) and 10.30.5.128/25 (prefix length 25); the /25 is more specific and wins. Option D is wrong because 10.30.5.130 falls within the subnet range of 10.30.5.128/25 (hosts .129–.254), so a valid route does exist.

Exam trap

Always prioritize the longest prefix match over broader subnets or default routes.

Why the other options are wrong

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.

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MCQhard

A static default route is configured with an administrative distance of 250. What is the most likely design intention?

A.To keep the route as a backup of last resort behind normal learned routes

B.To make the route override all dynamic routing immediately

C.To disable default routing entirely

D.To convert the default route into a host route

AnswerA

Administrative distance 250 exceeds the default values for connected, static, EIGRP, OSPF and RIP routes, so the static default only enters the routing table when all preferred routes fail. This deliberately makes it a floating static backup of last resort.

Why this answer

The design intention is to make the static default route a very low-priority backup path. In plain language, the administrator wants the route to exist only as a last resort behind almost any normal learned path. By assigning such a high administrative distance, the route stays out of the active table unless better routes disappear.

This is a floating-static design concept. The route is not meant to be primary. It is intentionally configured to sit in reserve and become relevant only during failure conditions or severe loss of normal routing information.

Exam trap

A common exam trap is assuming that increasing the administrative distance disables the static route or forces it to override dynamic routes. In reality, a higher AD causes the static route to be less preferred, effectively floating it behind all other routes. Candidates might confuse the AD value with route priority or think that setting it to 250 disables the route, but the route remains active and is used only as a last resort.

Misinterpreting this can lead to incorrect answers about route behavior and fail to recognize the floating static route design pattern.

Why the other options are wrong

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.

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MCQmedium

Exhibit: R1 has learned 10.50.0.0/24 through OSPF and also has a floating static route to the same prefix with administrative distance 130. Which route is installed while OSPF is healthy?

A.The static route because static routes always win over dynamic routes

B.The OSPF route because its administrative distance is lower than the floating static route

C.Both routes because the prefix length matches

D.Neither route until equal-cost load balancing is configured

AnswerB

The OSPF route is preferred because Cisco routers select the route with the lowest administrative distance when multiple routing protocols or static routes provide the same prefix. OSPF has an AD of 110, while the floating static route is intentionally configured with an AD of 130 (higher than the default static AD of 1) to act as a backup. Since 110 < 130, the router installs the OSPF route in the routing table and keeps the static route in standby until OSPF fails.

Why this answer

A floating static route is meant to stay out of the table until the preferred route disappears. OSPF has administrative distance 110, which is lower than the static route AD 130, so the OSPF route is installed while the OSPF path is still present.

Exam trap

Remember that administrative distance determines route preference. A lower value means higher preference.

Why the other options are wrong

This option is incorrect because static routes do not always win over dynamic routes; the route with the lowest administrative distance is preferred. In this case, OSPF has a lower administrative distance (110) than the floating static route (130).

This option is incorrect because only one route can be installed in the routing table for a specific prefix, and in this case, OSPF has a lower administrative distance than the floating static route, so only the OSPF route will be installed.

This option is incorrect because OSPF is healthy and has a lower administrative distance than the floating static route, meaning the OSPF route will be preferred and installed in the routing table.

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MCQhard

A packet is destined for 192.168.40.130. The routing table contains 192.168.40.0/24, 192.168.40.128/25, and 0.0.0.0/0. Which route is used?

A.192.168.40.0/24

B.192.168.40.128/25

C.0.0.0.0/0

D.No route can be used because the entries overlap

AnswerB

The /25 prefix is the longest match for 192.168.40.130, since that address falls within the 192.168.40.128–192.168.40.255 range. Longest-prefix match governs route selection, so this entry beats both the /24 covering 192.168.40.0–192.168.40.255 and the default route.

Why this answer

The /25 route is used because it is the most specific matching prefix. In plain language, even though the /24 and the default route also technically match, the router prefers the entry that most precisely describes the destination range. Since 192.168.40.130 falls inside 192.168.40.128/25, that route wins under longest-prefix match.

This is a classic routing-table interpretation pattern. The router does not start with the default route when more specific routes exist, and it does not choose the /24 simply because it is familiar. Specificity comes first.

Exam trap

A common exam trap is assuming that the default route or a larger subnet like /24 will be chosen over a more specific subnet like /25. Candidates may incorrectly think the default route is preferred or that overlapping routes cause ambiguity. However, routers always use the longest prefix match rule, which means the route with the most specific subnet mask that includes the destination IP is selected.

Misunderstanding subnet mask lengths or ignoring longest prefix match leads to wrong answers in routing questions.

Why the other options are wrong

192.168.40.0/24 is a valid route but less specific than 192.168.40.128/25. Since the destination IP falls within both, the router prefers the more specific /25 route, so this option is incorrect.

0.0.0.0/0 is the default route and only used when no other route matches. Since more specific routes exist for the destination IP, this option is incorrect.

Overlapping routes like /24 and /25 are common and resolved by longest prefix match. The presence of overlapping entries does not prevent route selection, so this option is incorrect.

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MCQhard

Refer to the exhibit. A network engineer is verifying OSPF routing on R1. All routers in the topology are expected to reside in OSPF area 0, and the network 172.16.0.0/16 should be advertised from R2 within the same area. The engineer issues the show ip route 172.16.0.0 command on R1 and sees the output in the exhibit. The engineer expected to see an intra-area route (O) instead of an inter-area route (O IA). What is the most likely cause of this discrepancy?

A.R1 has a mismatched OSPF process ID compared to the ABR.

B.The network type on GigabitEthernet0/0 is configured as non-broadcast, preventing full adjacency.

C.The metric for the route is too high, causing OSPF to treat it as an inter-area route.

D.The destination network 172.16.0.0/16 is located in a different OSPF area.

AnswerD

The routing table entry shows 'type inter area'. This indicates the prefix is being learned via an OSPF Type-3 summary LSA, which is only generated when the network is in a different area than the local router. Therefore, the network is indeed in a different area, contradicting the assumption that R1 and the destination are both in area 0.

Why this answer

The route 172.16.0.0/16 appears as O IA (inter-area) on R1, which means R1 learned it via a Type 3 LSA from an ABR. For the route to be intra-area (O), the destination network must reside in the same OSPF area (area 0) as R1. Since R2 is advertising this network, if it were truly in area 0, R1 would see an O route.

The O IA designation indicates that the network is in a different area, likely because R2's interface connected to 172.16.0.0/16 is configured in a different OSPF area, or R2 is acting as an ABR.

Exam trap

Cisco often tests the distinction between intra-area and inter-area OSPF routes, and the trap here is that candidates mistakenly think a high metric or mismatched process ID can change the route type, when in fact only the area configuration determines whether a route is O or O IA.

Why the other options are wrong

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

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

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

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MCQhard

A router has a static route configured: ip route 10.200.0.0 255.255.0.0 GigabitEthernet0/1. The output of show ip interface brief shows that interface GigabitEthernet0/1 is administratively down. Why is the route to 10.200.0.0/16 present in the running configuration but absent from the routing table?

A.Because the route points to an interface that is administratively down.

B.Because static routes cannot reference exit interfaces.

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

D.Because static routes require NTP before installation.

AnswerA

A static route that specifies only an exit interface is installed in the routing table only when that interface is in an up/up state. An administratively down interface (shutdown) makes the route invalid because the router cannot use that path for packet forwarding, even though the configuration exists. Therefore the route is absent from the show ip route output and no traffic is sent to 10.200.0.0/16.

Why this answer

The static route is absent because the outgoing interface is down. In practical terms, when a static route depends on an interface that is not operational, the router cannot use that path, so the route is not installed as usable forwarding state. The configuration line alone is not enough; the forwarding path also has to be viable.

This is a realistic static-route troubleshooting pattern because it distinguishes between configured intent and operational state.

Exam trap

A frequent exam trap is to confuse the presence of a static route in the configuration with its presence in the routing table. Candidates often overlook the fact that a static route pointing to an administratively down interface will not be installed, leading to the mistaken belief that the route is missing due to mask length or protocol requirements. Another trap is assuming static routes cannot use exit interfaces or require time synchronization, which is false.

This question tests the candidate's understanding of the difference between configured routes and operationally valid routes, focusing on interface state as the critical factor for route installation.

Why the other options are wrong

Incorrect because static routes can reference exit interfaces directly; Cisco routers support static routes with either next-hop IP addresses or exit interfaces.

Incorrect because the subnet mask length (such as /16 vs /24) does not prevent a static route from being installed; the issue is the interface state, not the mask.

Incorrect because static routes do not depend on NTP or time synchronization for installation; this is unrelated to static routing behavior.

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Multi-Selectmedium

Which TWO statements about interpreting routing table output are true? (Choose two.)

Select 2 answers

A.A route with a longer prefix length is always preferred over a route with a shorter prefix length, regardless of administrative distance.

B.A directly connected route has an administrative distance of 0 and is always preferred over any dynamic route for the same network.

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

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

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

AnswersA, B

The longest-prefix match rule is the first criterion in the routing table lookup: a route with a longer subnet mask (e.g., /32) is always selected over a less specific route (e.g., /24) for the same destination, even if that less specific route has a much lower administrative distance. Administrative distance becomes relevant only after the router identifies the set of routes with the longest matching prefix length. For example, a static route to 10.0.0.0/24 with AD 1 will lose to an OSPF route to 10.0.0.0/32 with AD 110, because specificity determines the winning route before AD is ever considered.

Why this answer

Longest-prefix match always wins regardless of AD or route source (A correct), and directly connected routes have AD 0 (B correct). C is incorrect because among equal prefix lengths, lower AD wins. D is wrong because metric only compares same-protocol routes, while AD compares across protocols.

E fails because a higher AD (200) is less preferred than OSPF's 110.

Exam trap

Cisco often tests the misconception that administrative distance is the primary tie-breaker, but the trap here is that the longest prefix match rule always takes precedence, even over a directly connected route with AD 0.

Why the other options are wrong

A lower AD indicates a more trustworthy source, so the route with the lower AD is preferred, not the higher one.

Metrics are only comparable within the same routing protocol (e.g., OSPF cost vs. EIGRP composite metric). For different protocols, AD is used to select the best route.

A lower AD is preferred; OSPF AD 110 is lower than 200, so the OSPF route would be chosen.

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