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CCNA Routing Fundamentals Questions

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76
MCQmedium

An administrator wants to drop traffic destined to the 10.10.10.0/24 network without sending an ICMP unreachable message back to the source. Which static route option should be used?

A.reject
B.discard
C.next-table
D.resolve
AnswerB

Discard drops traffic silently, no ICMP notification.

Why this answer

The correct answer is C. The 'discard' option drops traffic silently without generating ICMP unreachable, while 'reject' sends an ICMP unreachable. 'Next-table' forwards to another routing table, and 'resolve' requires a resolvable next-hop. Therefore, discard is the appropriate choice.

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77
MCQmedium

An administrator suspects that routing protocol updates are being sent to an incorrect next-hop. Which command can be used to capture and analyze the routing protocol packets on an interface?

A.show log messages | match ospf
B.show route forwarding-table
C.show ospf neighbor detail
D.monitor traffic interface ge-0/0/0.0
AnswerD

This command captures all packets on the interface for analysis.

Why this answer

The 'monitor traffic' command captures packets on an interface and allows analysis of routing updates. Option D is correct. Option A shows the forwarding table, not captures.

Option B shows log files but not real-time capture. Option C shows OSPF neighbor state, not packet contents.

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78
MCQmedium

An engineer configures two static routes to 172.16.0.0/16 with next-hops 10.0.1.1 and 10.0.2.1, both with the same preference and same metric. How does Junos handle traffic to this prefix?

A.It uses active/passive selection.
B.It load balances via ECMP.
C.It uses only the first configured route.
D.It drops traffic due to ambiguity.
AnswerB

Equal-cost multipath is enabled by default for static routes with equal preferences.

Why this answer

The correct answer is C. Junos supports equal-cost multipath (ECMP) by default for static routes with the same preference and metric. Traffic is load-balanced across both next-hops.

Option A is incorrect because active/passive is not default. Option B is incorrect because both routes are considered. Option D is incorrect because traffic is forwarded.

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79
MCQhard

You are the network engineer for a mid-sized enterprise with a Juniper MX router running Junos. The router has two uplinks to the internet: one to ISP-A via ge-0/0/0 (10.0.0.1/30) and one to ISP-B via ge-0/0/1 (10.0.0.5/30). You have configured static default routes to both ISPs: one to 10.0.0.2 and one to 10.0.0.6. Both routes have the same preference (default 5) and metric. You enabled ECMP to load-balance outbound traffic. After testing, you notice that all traffic is being sent only to ISP-A, and none to ISP-B. You verify that both interfaces are up and that the next-hop addresses are reachable. You check the routing table and see both routes are active but with different next-hop counts. What is the most likely cause of the traffic not being load-balanced?

A.One of the static routes resolves to multiple next hops, causing imbalance.
B.ECMP is not enabled in the forwarding-options.
C.The route to ISP-B is not active.
D.Hash-based load balancing requires per-packet configuration.
AnswerA

If one route resolves to multiple next hops, it may appear as multiple routes, skewing load balancing.

Why this answer

When both static default routes have the same preference and metric, Junos installs both in the routing table. However, ECMP load-balancing requires that each route resolve to a single next hop. If one static route resolves to multiple next hops (e.g., through a recursive lookup to a prefix with multiple paths), the route with a single next hop (ISP-A) becomes the sole active path for forwarding, while the multi-next-hop route (ISP-B) is not used for load balancing.

This explains why all traffic goes to ISP-A despite both routes being present.

Exam trap

The trap here is that candidates assume both routes are equally valid for ECMP simply because they appear in the routing table, but they overlook how recursive resolution can cause one route to have multiple next hops, breaking the equal-cost multipath condition.

How to eliminate wrong answers

Option B is wrong because ECMP is enabled by default in Junos when multiple equal-cost routes exist; no explicit 'forwarding-options' configuration is required for basic ECMP. Option C is wrong because the scenario states both routes are active in the routing table, so the route to ISP-B is indeed active. Option D is wrong because hash-based load balancing is the default behavior for ECMP in Junos; per-packet configuration is not needed for load balancing to occur, and the issue here is not about load-balancing mode but about next-hop resolution.

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80
MCQmedium

A static route with a next-hop of 10.0.0.1 is configured, but the route is not appearing in the active routing table. The output of `show route 10.0.0.1` shows that 10.0.0.1 is reachable via an OSPF route with preference 10. What is the most likely reason the static route is not active?

A.The OSPF route has a lower metric than the static route.
B.The static route's next-hop is not directly connected.
C.The static route is configured with a qualified-next-hop that fails.
D.The static route has a higher preference than OSPF.
AnswerC

A qualified-next-hop condition can prevent the static route from becoming active.

Why this answer

Option A is correct because the static route may be configured with a qualified-next-hop that is not satisfied. Option B is wrong because static route preference (5) is lower than OSPF (10), so static should be active. Option C is wrong because next-hop reachable via OSPF should allow static route to be active.

Option D is wrong because metric is not compared across protocols.

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81
Multi-Selecthard

A route is present in the routing table but is not active. Which three conditions could explain this? (Choose three.)

Select 3 answers
A.A route with a lower preference exists for the same destination.
B.The route is hidden due to a firewall filter.
C.The route is an aggregate route.
D.The next-hop is unreachable.
E.The route is a static route with a qualified-next-hop that is not satisfied.
AnswersA, D, E

A route with lower preference (more preferred) will be active, making the other route inactive.

Why this answer

A route with a lower preference (administrative distance) is preferred for the same destination prefix. In JUNOS, the route with the lowest preference value is installed as the active route in the forwarding table. If a route has a higher preference, it remains in the routing table as a backup but is not marked as active.

Exam trap

The trap here is that candidates often confuse firewall filters with routing policy or route filters, thinking they can hide routes, but firewall filters operate on packet forwarding, not on the routing table itself.

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82
MCQeasy

What is the default preference of a direct route in Junos?

A.0
B.10
C.5
D.15
AnswerA

Direct routes have preference 0.

Why this answer

Direct routes in Junos have a default preference of 0, which is the highest possible preference (lowest numerical value). This ensures that directly connected routes are always preferred over any other route type, including static routes (preference 5) and OSPF internal routes (preference 10). The preference value is used by Junos to select the best route when multiple routes exist to the same destination.

Exam trap

The trap here is that candidates often confuse Junos route preferences with Cisco administrative distances, where directly connected routes have an AD of 0 in Cisco as well, but Junos uses the term 'preference' and the values differ for other route types (e.g., static is 5 in Junos vs. 1 in Cisco).

How to eliminate wrong answers

Option B (10) is wrong because 10 is the default preference for OSPF internal routes, not direct routes. Option C (5) is wrong because 5 is the default preference for static routes in Junos, not direct routes. Option D (15) is wrong because 15 is not a default preference for any common route type in Junos; it may be confused with the preference for IS-IS Level 1 routes (15) or OSPF external routes (150).

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83
MCQmedium

An engineer configures a static route to 192.168.0.0/16 with next-hop 172.16.1.1. The router has a directly connected route for 172.16.1.0/30 via interface ge-0/0/0.1. However, the static route appears as 'hidden' in the routing table. What is the most likely cause?

A.The static route preference is set too high
B.The next-hop address 172.16.1.1 is unreachable
C.The static route has not been committed
D.The static route is a discard route
AnswerB

If the next-hop is unreachable, the route is hidden because the router cannot resolve it.

Why this answer

A hidden static route typically means the next-hop is not reachable. Option D correctly identifies this. Option A is incorrect because high preference does not cause hidden; it may not be active but still visible.

Option B is incorrect because a discard route would be flagged as 'discard'. Option C is incorrect because the route is committed if it appears in the configuration.

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84
MCQmedium

Refer to the exhibit. Why is the route via 10.0.0.1 selected as the active route?

A.It has a lower metric
B.It has a lower cost
C.It is an older route
D.It has a lower preference
AnswerD

Preference 10 is lower than 150, so it is preferred.

Why this answer

The correct answer is B. The active route has preference 10, while the alternative has preference 150. In Junos, the route with the lower preference is preferred.

Option A is incorrect because metric (1 vs 20) is not considered since preferences differ. Option C is incorrect because cost is not a separate factor; metric is the OSPF cost. Option D is incorrect because route age is not a tie-breaker when preferences differ.

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85
MCQeasy

Refer to the exhibit. How many next hops are installed for the 10.1.1.0/24 route?

A.4
B.2
C.3
D.1
AnswerB

Two next hops are shown: one active (with '>') and another without.

Why this answer

The exhibit shows two next hops: 192.168.1.1 and 192.168.2.1. Both are installed as part of an ECMP or redundancy setup.

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86
MCQhard

Refer to the exhibit. A network administrator configured a static route to 10.0.0.0/24 with next-hop 192.168.1.1. The route is not appearing in the active routing table. What is the most likely reason?

A.The next-hop address is not reachable.
B.The route is a reject route.
C.The route is being overridden by an OSPF route with lower preference.
D.The static route preference is too high.
AnswerA

Correct: the exhibit shows 'Next hop type: Unreachable', meaning 192.168.1.1 is not reachable, so the route is not installed.

Why this answer

The exhibit shows the route's next-hop type as 'Unreachable', indicating that 192.168.1.1 is not reachable. Option B is correct. Option A is incorrect because the preference of 5 is low, and a higher preference would make it less preferred, but the route is not active due to next-hop unreachability.

Option C is incorrect: if an OSPF route with lower preference (higher priority) existed, it would be active, but the static route would still be present as a backup; the exhibit shows the route is not active because the next-hop is unreachable. Option D is incorrect: a reject route would show a next-hop of 'Reject' or 'Discard'.

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87
MCQeasy

A Juniper device receives several routes to the same destination prefix from different routing protocols. Which parameter is used first to select the active route?

A.Route preference (administrative distance)
B.Metric
C.AS path length
D.Local preference
AnswerA

Route preference is the primary tie-breaker for routes from different protocols.

Why this answer

Option C is correct because route preference (administrative distance) is compared first when routes are from different protocols. Options A and B are BGP-specific and used after preference. Option D is used within the same protocol only.

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88
MCQhard

An enterprise uses OSPF across multiple areas. To reduce routing table size in the backbone area, the engineer wants to advertise a single summary route for all subnets in area 2. Which configuration is appropriate?

A.Configure a virtual-link between area 2 and area 0
B.Configure a default route from area 2 using 'default-metric'
C.Use a static route for the summary and redistribute it into OSPF
D.Configure 'area 2 area-range 10.0.0.0/16' on the ABR
AnswerD

This summarizes area 2's routes into a single prefix for other areas.

Why this answer

Option D is correct because the 'area-range' command on an Area Border Router (ABR) allows you to summarize a set of routes from a specific area into the backbone (area 0) by advertising a single aggregate route (e.g., 10.0.0.0/16) instead of all individual subnets. This reduces the routing table size in area 0 while still providing reachability to all subnets in area 2.

Exam trap

The trap here is that candidates often confuse 'area-range' (which summarizes routes between areas) with 'virtual-link' (which fixes connectivity issues) or assume redistribution is needed for summarization, when OSPF's built-in ABR summarization is the correct and simplest method.

How to eliminate wrong answers

Option A is wrong because a virtual-link is used to connect a non-backbone area to area 0 when the area is physically disconnected, not for route summarization; it does not create a summary route. Option B is wrong because 'default-metric' is used to set the metric for default routes redistributed into OSPF, but it does not summarize area-specific subnets into a single route. Option C is wrong because using a static route and redistributing it into OSPF would create a separate external route (type 5 LSA) rather than a type 3 summary LSA, and it would not automatically summarize all subnets in area 2; it also adds administrative overhead and may cause suboptimal routing.

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89
MCQhard

Refer to the exhibit. Why is the static route not active?

A.The OSPF route has a lower metric.
B.The static route's next-hop is not reachable.
C.The static route is not committed.
D.The static route has a higher preference than the OSPF route.
AnswerD

Static preference 15 is higher (less preferred) than OSPF preference 10, so OSPF is active.

Why this answer

Option C is correct because the static route has a preference of 15, which is higher than OSPF's preference of 10, making OSPF the active route. Option A is wrong because metric is not compared across protocols. Option B is wrong because the next-hop is reachable (via ge-0/0/0.0).

Option D is wrong because the route is present in the table, so it is committed.

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90
Multi-Selecthard

Which TWO configuration statements are valid for defining a static route on a Junos device?

Select 2 answers
A.set routing-options static route 10.0.0.0/8 discard
B.set routing-options static route 10.0.0.0/8 reject-all
C.set routing-options static route 10.0.0.0/8 qualified-next-hop 192.168.1.1 preference 10
D.set routing-options static route 10.0.0.0/8 next-hop 192.168.1.1 metric 10
E.set routing-options static route 10.0.0.0/8 passive
AnswersA, C

Valid: discard is a valid next-hop action.

Why this answer

Valid static route configurations include next-hop (IP, interface), discard, reject, qualified-next-hop, next-table, etc. Invalid include metric, passive, and misspelled keywords.

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91
MCQmedium

You configure an aggregate route for 172.16.0.0/16. What must exist for this aggregate to be active in the routing table?

A.A directly connected interface on that subnet
B.A static route to the aggregate prefix
C.A contributing route (more specific route within the aggregate range)
D.Nothing; the aggregate is always active once committed.
AnswerC

Aggregates are active only when a more specific route exists in the routing table.

Why this answer

The correct answer is A. An aggregate route requires at least one contributing route (a more specific route within the aggregate's range) to become active. Without a contributing route, the aggregate remains inactive.

Option B is not required, though a static route can serve as contributor. Option C is not required. Option D is false; a contributing route must exist.

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92
MCQhard

A service provider is migrating from a legacy core network to Juniper MX series routers. In the new design, each MX router runs OSPF as the IGP with a single backbone area 0 and multiple non-backbone areas for customer aggregation. The network uses route summarization at area border routers (ABRs) to reduce routing table size. During testing, engineers notice that some customer prefixes from area 1 are not being propagated to the backbone area, even though the ABR has a valid route to those prefixes and has been configured with 'area 1 range 192.168.0.0/16'. The ABR is an MX240 running Junos 21.4R1. The 'show ospf route' command on the ABR shows the individual customer prefixes (e.g., 192.168.1.0/24) in the OSPF routing table, but the summary route is not present in the backbone area's database. Additionally, 'show ospf database summary' on a backbone router does not show the summary LSA for 192.168.0.0/16. What is the most likely cause?

A.The summary LSA is being suppressed because the ABR is also advertising a type 5 external route for the same prefix.
B.The ABR has no interface in area 1 that matches the summary range; the 'area range' command requires a directly connected interface.
C.The 'area range' command only works after a routing process restart; a 'clear ospf database' is required to regenerate LSAs.
D.The individual prefixes from area 1 may not be installed in the inet.0 routing table on the ABR, possibly due to a missing OSPF adjacency or a route filter blocking them.
AnswerD

Without a valid inter-area route, the ABR cannot generate the summary.

Why this answer

Option D is correct because the 'area range' command requires an active inter-area route to exist in the routing table; if the ABR does not have a route to the individual prefixes in the inet.0 table (perhaps due to filtering or no OSPF adjacency), the summary is not generated. Option A is incorrect; the area range command itself works, but a restart is not required. Option B is incorrect; the area range does not need a matching interface; it summarizes routes learned from the area.

Option C is incorrect; the summary LSA is type 3, not type 5.

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93
Multi-Selectmedium

Which THREE conditions must be met for a route to be considered active in the JunOS routing table? (Choose three.)

Select 3 answers
A.The route is the only route for the prefix
B.The route is from a trusted protocol
C.The route is preferred based on protocol preference
D.The route is installed in the forwarding table
E.The next-hop is reachable
AnswersC, D, E

Only the route with the lowest preference among all routes for the prefix is active.

Why this answer

A route is active if it is the best route (lowest preference), its next-hop is reachable, and it is installed in the forwarding table. Options A, B, and D are correct. Option C is incorrect because multiple routes can exist for the same prefix (only one active).

Option E is incorrect because 'trusted protocol' is not a condition.

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94
Multi-Selecteasy

Which two statements are true about static routes on Juniper devices? (Choose two.)

Select 2 answers
A.A static route with a next-hop of an IP address requires that the next-hop be reachable.
B.Static routes can be configured with a qualified-next-hop to provide conditional routing.
C.A static route with a next-hop of an interface will be active even if the interface is down.
D.A static route with a preference of 10 is preferred over a static route with a preference of 5.
E.Static routes cannot be used for load balancing.
AnswersA, B

The route becomes active only if the next-hop is reachable in the routing table.

Why this answer

Options B and E are correct. Option A is false because a static route with a next-hop of an interface is not active if the interface is down. Option C is false because static routes can be used for load balancing.

Option D is false because a lower preference number indicates a more preferred route.

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95
MCQeasy

What is the default preference value of a directly connected (direct) route in JunOS?

A.10
B.170
C.0
D.100
AnswerC

Direct routes have a preference of 0.

Why this answer

In JunOS, directly connected routes have a default preference value of 0, which is the highest possible preference (lowest numerical value). This ensures that directly connected routes are always preferred over routes learned from any dynamic routing protocol, as they represent interfaces that are directly reachable on the local device.

Exam trap

The trap here is that Cisco uses a default administrative distance of 0 for directly connected routes as well, but candidates often confuse JunOS preference values with Cisco administrative distances, leading them to incorrectly select 10 (OSPF) or 100 (static) as the default for direct routes.

How to eliminate wrong answers

Option A is wrong because 10 is the default preference for OSPF internal routes in JunOS, not for directly connected routes. Option B is wrong because 170 is the default preference for BGP routes (both EBGP and IBGP) in JunOS, not for directly connected routes. Option D is wrong because 100 is the default preference for static routes in JunOS, not for directly connected routes.

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96
MCQeasy

A network administrator configures a default route using 'set routing-options static route 0.0.0.0/0 next-hop 10.0.0.1 preference 10' and later enables OSPF which also advertises a default route with default preference 150. Which route becomes active in the routing table?

A.Neither route becomes active due to conflicting protocols
B.Both routes are active for ECMP load balancing
C.Static route to 0.0.0.0/0 with next-hop 10.0.0.1
D.OSPF route to 0.0.0.0/0
AnswerC

Static route has lower preference (10) and becomes active.

Why this answer

The static route with preference 10 is preferred over the OSPF route with preference 150 because JunOS selects the route with the lowest preference value. Option A is correct. Option B is incorrect because higher preference is less preferred.

Option C is incorrect because ECMP requires equal cost routes, not different preference. Option D is incorrect because the static route is valid.

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97
Multi-Selectmedium

Which THREE statements are true regarding static routes in Junos?

Select 3 answers
A.A static route can have a next-hop of a directly connected interface.
B.Static routes require OSPF to be enabled on the router.
C.Static routes automatically generate ICMP redirect messages.
D.A static route can be configured to discard traffic.
E.The default preference for a static route is 5.
AnswersA, D, E

Static routes can use a next-hop of an interface, e.g., 'set route 0.0.0.0/0 next-hop ge-0/0/0.0'.

Why this answer

A static route can have a next-hop of a directly connected interface, meaning the router will consider the destination as directly reachable out that interface without needing an explicit IP next-hop. This is valid in Junos and is often used for point-to-point links or when the next-hop address is not required.

Exam trap

The trap here is that candidates may confuse the default preference of static routes in Junos (5) with Cisco's default administrative distance (1), leading them to incorrectly reject option E or assume static routes require a dynamic protocol like OSPF.

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