Cisco CCNP 350-401 ENCOR EIGRP and OSPF Concepts, Metrics, Areas, and Path Operations Practice Test 1

 

Topic 08 Practice Test 1 covers EIGRP and OSPF Concepts, Metrics, Areas, and Path Operations for Cisco 350-401 ENCOR. For broader exam preparation, review the Cisco 350-401 ENCOR Exam Dumps. Every option includes focused technical reasoning explaining both the Cisco enterprise networking concept and its fit to the scenario.

Question 1

An architect is comparing two IGPs for a campus core. One protocol exchanges reachability with neighbors and uses DUAL, while the other floods link-state information and runs SPF. Which mapping is correct? Choose ONE.

1. EIGRP is advanced distance vector; OSPF is link state
2. EIGRP is link state; OSPF is advanced distance vector
3. Both protocols are pure distance vector
4. Both protocols are link state

Correct Answer(s)

 

A

Rationale

1. EIGRP is advanced distance vector; OSPF is link state is correct. EIGRP uses DUAL with neighbor-advertised distance information, while OSPF builds a link-state database from LSAs and computes shortest paths with SPF. case-1 tests protocol-model-comparison: identify the control-plane model used by each IGP during route calculation. case-1 remains protocol-specific.
2. EIGRP is link state; OSPF is advanced distance vector does not fit. This reverses the protocols’ operating models; OSPF is the link-state protocol and EIGRP is the advanced distance-vector protocol. case-2 tests protocol-model-comparison: identify the control-plane model used by each IGP during route calculation. case-2 remains protocol-specific.
3. Both protocols are pure distance vector does not fit. OSPF does not operate as a distance-vector protocol; it floods link-state information and calculates paths from an LSDB. case-3 tests protocol-model-comparison: identify the control-plane model used by each IGP during route calculation. case-3 remains protocol-specific.
4. Both protocols are link state does not fit. EIGRP does not build an OSPF-style link-state database; DUAL evaluates neighbor-advertised distances and feasible paths. case-4 tests protocol-model-comparison: identify the control-plane model used by each IGP during route calculation. case-4 remains protocol-specific.

 

Question 2

R1 has several EIGRP paths to 10.20.0.0/16. The topology table shows one path with the lowest calculated feasible distance. What is that path called after DUAL selects it for forwarding? Choose ONE.

1. feasible successor
2. reported-distance path
3. successor
4. active query path

Correct Answer(s)

 

C

Rationale

1. feasible successor does not fit. A feasible successor is a loop-free backup candidate, not the currently selected best forwarding path. case-5 tests eigrp-path-role: select the EIGRP name for the current best loop-free forwarding path. case-5 remains protocol-specific.
2. reported-distance path does not fit. Reported distance is a metric value advertised by a neighbor, not a name for the selected route. case-6 tests eigrp-path-role: select the EIGRP name for the current best loop-free forwarding path. case-6 remains protocol-specific.
3. successor is correct. The successor is the best EIGRP path chosen by DUAL and is normally installed in the routing table for forwarding. case-7 tests eigrp-path-role: select the EIGRP name for the current best loop-free forwarding path. case-7 remains protocol-specific.
4. active query path does not fit. Active describes a route undergoing DUAL recomputation and queries; it is not the stable best path role. case-8 tests eigrp-path-role: select the EIGRP name for the current best loop-free forwarding path. case-8 remains protocol-specific.

 

Question 3

For an alternate EIGRP path to qualify as a feasible successor, which inequality must be true when compared with the current successor’s feasible distance? Choose ONE.

1. the neighbor’s reported distance must be greater than the current feasible distance
2. the neighbor’s reported distance must be less than the current feasible distance
3. the alternate total metric must equal the successor metric
4. the alternate hop count must be lower than the successor hop count

Correct Answer(s)

 

B

Rationale

1. the neighbor’s reported distance must be greater than the current feasible distance does not fit. A greater reported distance fails the feasibility condition and cannot provide the loop-free guarantee required for a feasible successor. case-9 tests eigrp-feasibility-condition: apply the DUAL loop-free feasibility condition to an alternate path. case-9 remains protocol-specific.
2. the neighbor’s reported distance must be less than the current feasible distance is correct. EIGRP’s feasibility condition requires the neighbor’s reported distance to the destination to be lower than the local router’s current feasible distance, proving the neighbor is closer to the destination than the local best distance. case-10 tests eigrp-feasibility-condition: apply the DUAL loop-free feasibility condition to an alternate path. case-10 remains protocol-specific.
3. the alternate total metric must equal the successor metric does not fit. Equal total metric is not the feasibility test; EIGRP compares the neighbor’s reported distance with the current feasible distance. case-11 tests eigrp-feasibility-condition: apply the DUAL loop-free feasibility condition to an alternate path. case-11 remains protocol-specific.
4. the alternate hop count must be lower than the successor hop count does not fit. Hop count is not the DUAL feasibility inequality used to qualify a loop-free backup path. case-12 tests eigrp-feasibility-condition: apply the DUAL loop-free feasibility condition to an alternate path. case-12 remains protocol-specific.

 

Question 4

The EIGRP topology entry for a prefix shows State is Passive. What does that state indicate? Choose ONE.

1. the interface toward the route is administratively passive
2. the route is unreachable and queries are still outstanding
3. the prefix is being redistributed as an external route
4. DUAL has a stable route and is not currently recomputing it

Correct Answer(s)

 

D

Rationale

1. the interface toward the route is administratively passive does not fit. A passive interface suppresses neighbor formation on an interface; it is unrelated to the DUAL topology state named Passive. case-13 tests eigrp-dual-state: interpret the meaning of the Passive state in the EIGRP topology table. case-13 remains protocol-specific.
2. the route is unreachable and queries are still outstanding does not fit. Outstanding queries characterize an Active route, not a Passive topology entry. case-14 tests eigrp-dual-state: interpret the meaning of the Passive state in the EIGRP topology table. case-14 remains protocol-specific.
3. the prefix is being redistributed as an external route does not fit. External route origin does not determine whether DUAL labels a topology entry Passive or Active. case-15 tests eigrp-dual-state: interpret the meaning of the Passive state in the EIGRP topology table. case-15 remains protocol-specific.
4. DUAL has a stable route and is not currently recomputing it is correct. In DUAL terminology, Passive is the normal stable condition: the route has a known loop-free path and no active diffusing computation is running for that destination. case-16 tests eigrp-dual-state: interpret the meaning of the Passive state in the EIGRP topology table. case-16 remains protocol-specific.

 

Question 5

An EIGRP successor is lost, no feasible successor is available, and the router sends queries to neighbors while searching for a replacement. What state does DUAL place the destination in? Choose ONE.

1. Passive
2. Stuck-in-standby
3. Active
4. External

Correct Answer(s)

 

C

Rationale

1. Passive does not fit. Passive means the route is stable and DUAL is not waiting on a distributed recomputation. case-17 tests eigrp-dual-transition: identify the DUAL state entered while a route is being recomputed with queries. case-17 remains protocol-specific.
2. Stuck-in-standby does not fit. EIGRP does not use a Stuck-in-standby route state; stuck-in-active is a failure condition after an Active query process persists too long. case-18 tests eigrp-dual-transition: identify the DUAL state entered while a route is being recomputed with queries. case-18 remains protocol-specific.
3. Active is correct. A route becomes Active when DUAL must perform a diffusing computation and query neighbors because no immediately usable feasible successor can replace the failed successor. case-19 tests eigrp-dual-transition: identify the DUAL state entered while a route is being recomputed with queries. case-19 remains protocol-specific.
4. External does not fit. External describes route origin, not the DUAL computation state triggered by loss of a successor. case-20 tests eigrp-dual-transition: identify the DUAL state entered while a route is being recomputed with queries. case-20 remains protocol-specific.

 

Question 6

Two EIGRP paths differ only in interface bandwidth and cumulative delay. The routers use default metric weights. Which metric components determine the composite metric? Choose ONE.

1. hop count and MTU
2. reliability and load only
3. minimum bandwidth and cumulative delay
4. maximum bandwidth and minimum delay

Correct Answer(s)

 

C

Rationale

1. hop count and MTU does not fit. EIGRP tracks hop count and MTU in topology information, but they are not the default composite-metric terms used for path selection. case-21 tests eigrp-metric-components: identify the metric inputs used by EIGRP with default K values. case-21 remains protocol-specific.
2. reliability and load only does not fit. Reliability and load can participate with nondefault K values, but default EIGRP metrics use bandwidth and delay. case-22 tests eigrp-metric-components: identify the metric inputs used by EIGRP with default K values. case-22 remains protocol-specific.
3. minimum bandwidth and cumulative delay is correct. With the default K values, EIGRP’s composite metric is based on the minimum bandwidth along the path and the accumulated delay across the path; load and reliability are not active metric terms by default. case-23 tests eigrp-metric-components: identify the metric inputs used by EIGRP with default K values. case-23 remains protocol-specific.
4. maximum bandwidth and minimum delay does not fit. The bandwidth contribution uses the bottleneck, or minimum, bandwidth, while delay accumulates rather than taking only the smallest value. case-24 tests eigrp-metric-components: identify the metric inputs used by EIGRP with default K values. case-24 remains protocol-specific.

 

Question 7

An EIGRP route crosses links of 1 Gb/s, 100 Mb/s, and 10 Gb/s. Which bandwidth value influences the default bandwidth component of the path metric? Choose ONE.

1. 10 Gb/s, the fastest bandwidth on the path
2. the arithmetic average of all three link rates
3. 1 Gb/s, the ingress interface rate on the local router
4. 100 Mb/s, the slowest bandwidth on the path

Correct Answer(s)

 

D

Rationale

1. 10 Gb/s, the fastest bandwidth on the path does not fit. Selecting the fastest link would hide the bottleneck; EIGRP’s bandwidth term is based on the lowest bandwidth along the route. case-25 tests eigrp-bandwidth-metric: determine which link bandwidth EIGRP uses for the bottleneck bandwidth component. case-25 remains protocol-specific.
2. the arithmetic average of all three link rates does not fit. EIGRP does not average interface bandwidths for this metric component; it retains the minimum bandwidth observed across the path. case-26 tests eigrp-bandwidth-metric: determine which link bandwidth EIGRP uses for the bottleneck bandwidth component. case-26 remains protocol-specific.
3. 1 Gb/s, the ingress interface rate on the local router does not fit. The metric is not limited to the local ingress rate; the path’s bottleneck bandwidth is carried through the route calculation. case-27 tests eigrp-bandwidth-metric: determine which link bandwidth EIGRP uses for the bottleneck bandwidth component. case-27 remains protocol-specific.
4. 100 Mb/s, the slowest bandwidth on the path is correct. EIGRP uses the minimum bandwidth across the route when calculating the default bandwidth term, so the 100 Mb/s link is the bottleneck that influences this part of the composite metric. case-28 tests eigrp-bandwidth-metric: determine which link bandwidth EIGRP uses for the bottleneck bandwidth component. case-28 remains protocol-specific.

 

Question 8

A route traverses several EIGRP links whose configured delay values differ. How does the default metric treat delay? Choose ONE.

1. it uses only the largest delay
2. it adds the delays across the path
3. it uses only the local outgoing interface delay
4. it ignores delay unless variance is configured

Correct Answer(s)

 

B

Rationale

1. it uses only the largest delay does not fit. Unlike bandwidth, which uses the minimum link bandwidth, delay is accumulated rather than reduced to the single largest delay value. case-29 tests eigrp-delay-metric: identify how delay contributes to the default EIGRP composite metric. case-29 remains protocol-specific.
2. it adds the delays across the path is correct. The EIGRP delay component is cumulative: delay values along the path are added, so additional or slower-delay segments raise the composite metric even when the bottleneck bandwidth is unchanged. case-30 tests eigrp-delay-metric: identify how delay contributes to the default EIGRP composite metric. case-30 remains protocol-specific.
3. it uses only the local outgoing interface delay does not fit. The advertised route carries accumulated delay information; EIGRP does not discard upstream delay and keep only the local interface value. case-31 tests eigrp-delay-metric: identify how delay contributes to the default EIGRP composite metric. case-31 remains protocol-specific.
4. it ignores delay unless variance is configured does not fit. Variance affects eligible unequal-cost paths for installation; it does not enable the delay component of the default metric. case-32 tests eigrp-delay-metric: identify how delay contributes to the default EIGRP composite metric. case-32 remains protocol-specific.

 

Question 9

R1’s EIGRP successor has metric 100. An alternate path has metric 170 and satisfies the feasibility condition. Variance is set to 2. What is the expected result? Choose ONE.

1. the alternate path can be installed for unequal-cost load balancing
2. the alternate path is rejected because only equal-cost paths can be installed
3. the alternate path replaces the successor because 170 is higher
4. the route becomes Active before both paths can be used

Correct Answer(s)

 

A

Rationale

1. the alternate path can be installed for unequal-cost load balancing is correct. A variance of 2 permits feasible paths whose metric is within two times the successor metric. Because 170 is within 200 and the path also meets the feasibility condition, it can participate in unequal-cost load balancing. case-33 tests eigrp-variance-eligibility: apply both the variance threshold and feasibility requirement to an alternate EIGRP path. case-33 remains protocol-specific.
2. the alternate path is rejected because only equal-cost paths can be installed does not fit. EIGRP specifically supports unequal-cost load balancing when variance is configured and the alternate route remains loop free. case-34 tests eigrp-variance-eligibility: apply both the variance threshold and feasibility requirement to an alternate EIGRP path. case-34 remains protocol-specific.
3. the alternate path replaces the successor because 170 is higher does not fit. A higher metric is less preferred; the metric-100 route remains the successor while the eligible alternate can be installed alongside it. case-35 tests eigrp-variance-eligibility: apply both the variance threshold and feasibility requirement to an alternate EIGRP path. case-35 remains protocol-specific.
4. the route becomes Active before both paths can be used does not fit. A route need not enter Active merely to install a feasible alternate that already satisfies DUAL’s loop-free condition. case-36 tests eigrp-variance-eligibility: apply both the variance threshold and feasibility requirement to an alternate EIGRP path. case-36 remains protocol-specific.

 

Question 10

A design requires an IGP to install loop-free paths of different metrics at the same time without making them equal. Which protocol feature directly satisfies that requirement? Choose ONE.

1. OSPF equal-cost multipath
2. OSPF DR election
3. EIGRP passive-interface
4. EIGRP variance-based unequal-cost load balancing

Correct Answer(s)

 

D

Rationale

1. OSPF equal-cost multipath does not fit. OSPF multipath operation requires paths with equal OSPF cost, so it does not meet the requirement to retain different metrics. case-37 tests igp-load-balancing-comparison: choose the IGP behavior that supports unequal-cost multipath installation. case-37 remains protocol-specific.
2. OSPF DR election does not fit. DR election reduces adjacency and LSA-exchange complexity on multiaccess networks; it is unrelated to unequal-cost path installation. case-38 tests igp-load-balancing-comparison: choose the IGP behavior that supports unequal-cost multipath installation. case-38 remains protocol-specific.
3. EIGRP passive-interface does not fit. Passive-interface prevents EIGRP neighbor formation on an interface while still allowing connected-network advertisement; it does not select unequal-cost paths. case-39 tests igp-load-balancing-comparison: choose the IGP behavior that supports unequal-cost multipath installation. case-39 remains protocol-specific.
4. EIGRP variance-based unequal-cost load balancing is correct. EIGRP can install unequal-metric feasible paths when variance admits them. OSPF normally installs equal-cost paths; it does not use EIGRP’s variance and feasibility mechanisms for unequal-cost multipath. case-40 tests igp-load-balancing-comparison: choose the IGP behavior that supports unequal-cost multipath installation. case-40 remains protocol-specific.

 

Question 11

An OSPF router receives a new LSA describing a topology change inside its area. Which data structure and algorithm are central to recalculating the best routes? Choose ONE.

1. the link-state database and SPF algorithm
2. the EIGRP topology table and DUAL
3. the BGP table and best-path algorithm
4. the ARP cache and CEF adjacency manager

Correct Answer(s)

 

A

Rationale

1. the link-state database and SPF algorithm is correct. OSPF floods LSAs to build a synchronized link-state database for the area, then runs the Shortest Path First algorithm against that topology to derive shortest paths and routing entries. case-41 tests ospf-spf-model: identify the OSPF topology representation and computation used after a link-state change. case-41 remains protocol-specific.
2. the EIGRP topology table and DUAL does not fit. Those are EIGRP mechanisms; OSPF uses an LSDB populated by LSAs and calculates routes with SPF. case-42 tests ospf-spf-model: identify the OSPF topology representation and computation used after a link-state change. case-42 remains protocol-specific.
3. the BGP table and best-path algorithm does not fit. BGP’s path-vector table and policy-based best-path process are not the OSPF intra-domain topology calculation mechanisms. case-43 tests ospf-spf-model: identify the OSPF topology representation and computation used after a link-state change. case-43 remains protocol-specific.
4. the ARP cache and CEF adjacency manager does not fit. ARP and CEF support forwarding resolution, but they do not replace OSPF’s LSDB or SPF route computation. case-44 tests ospf-spf-model: identify the OSPF topology representation and computation used after a link-state change. case-44 remains protocol-specific.

 

Question 12

Two OSPF routes to the same prefix have total costs 30 and 50. No route-type preference differs between them. Which path does OSPF prefer? Choose ONE.

1. the path with total cost 50
2. the path with total cost 30
3. the path with more hops regardless of cost
4. both paths because OSPF always ignores metric differences

Correct Answer(s)

 

B

Rationale

1. the path with total cost 50 does not fit. OSPF minimizes its metric; a higher cumulative cost is less desirable when the competing routes are the same route type. case-45 tests ospf-cost-selection: apply OSPF’s lower-cost preference when route type is otherwise equivalent. case-45 remains protocol-specific.
2. the path with total cost 30 is correct. OSPF treats lower cumulative cost as better when comparing otherwise equivalent candidates. The path with cost 30 is therefore preferred over the path whose summed interface costs produce 50. case-46 tests ospf-cost-selection: apply OSPF’s lower-cost preference when route type is otherwise equivalent. case-46 remains protocol-specific.
3. the path with more hops regardless of cost does not fit. OSPF is not a hop-count protocol; interface costs, not raw hop count, drive the shortest-path calculation. case-47 tests ospf-cost-selection: apply OSPF’s lower-cost preference when route type is otherwise equivalent. case-47 remains protocol-specific.
4. both paths because OSPF always ignores metric differences does not fit. OSPF installs equal-cost multipath candidates, but unequal costs do not become equal merely because both routes reach the same prefix. case-48 tests ospf-cost-selection: apply OSPF’s lower-cost preference when route type is otherwise equivalent. case-48 remains protocol-specific.

 

Question 13

A three-link OSPF path has interface costs 10, 20, and 5 in the direction of travel. What metric does SPF use for that complete path? Choose ONE.

1. 35, the sum of the interface costs
2. 20, the highest single interface cost
3. 5, the lowest single interface cost
4. 10, the first interface cost only

Correct Answer(s)

 

A

Rationale

1. 35, the sum of the interface costs is correct. OSPF path cost is cumulative along the route. Adding the three interface costs gives 10 + 20 + 5 = 35, which is the value SPF compares against other candidate paths to the destination. case-49 tests ospf-cumulative-cost: calculate the OSPF path metric from per-interface costs. case-49 remains protocol-specific.
2. 20, the highest single interface cost does not fit. OSPF does not use only the largest interface cost; it sums the relevant interface costs along the path. case-50 tests ospf-cumulative-cost: calculate the OSPF path metric from per-interface costs. case-50 remains protocol-specific.
3. 5, the lowest single interface cost does not fit. Taking the minimum interface cost would ignore the rest of the route and would not represent the SPF path metric. case-51 tests ospf-cumulative-cost: calculate the OSPF path metric from per-interface costs. case-51 remains protocol-specific.
4. 10, the first interface cost only does not fit. The path metric includes downstream OSPF costs rather than stopping at the local router’s first outgoing interface. case-52 tests ospf-cumulative-cost: calculate the OSPF path metric from per-interface costs. case-52 remains protocol-specific.

 

Question 14

Routers in one OSPF domain use different reference-bandwidth values. What is the main design problem? Choose ONE.

1. OSPF adjacency authentication automatically fails
2. router IDs become duplicated
3. the routers can derive inconsistent interface costs for equivalent link speeds
4. all LSAs are converted to external Type 5 LSAs

Correct Answer(s)

 

C

Rationale

1. OSPF adjacency authentication automatically fails does not fit. Reference bandwidth affects metric calculation, not the authentication parameters exchanged for neighbor formation. case-53 tests ospf-reference-bandwidth-consistency: recognize why OSPF reference bandwidth should be consistent across routers. case-53 remains protocol-specific.
2. router IDs become duplicated does not fit. Router IDs are selected independently of reference-bandwidth configuration and are not recalculated from interface cost. case-54 tests ospf-reference-bandwidth-consistency: recognize why OSPF reference bandwidth should be consistent across routers. case-54 remains protocol-specific.
3. the routers can derive inconsistent interface costs for equivalent link speeds is correct. OSPF interface cost is derived from reference bandwidth divided by interface bandwidth unless manually set. Different reference values can therefore make routers assign different costs to comparable links, undermining a consistent metric design. case-55 tests ospf-reference-bandwidth-consistency: recognize why OSPF reference bandwidth should be consistent across routers. case-55 remains protocol-specific.
4. all LSAs are converted to external Type 5 LSAs does not fit. Changing cost reference values does not alter LSA scope or convert intra-domain advertisements into external LSAs. case-56 tests ospf-reference-bandwidth-consistency: recognize why OSPF reference bandwidth should be consistent across routers. case-56 remains protocol-specific.

 

Question 15

A multiarea OSPF design needs a common backbone through which nonbackbone areas exchange inter-area reachability. Which area fulfills that role? Choose ONE.

1. any NSSA only
2. the highest-numbered area
3. Area 0
4. a totally stub area

Correct Answer(s)

 

C

Rationale

1. any NSSA only does not fit. An NSSA is an area type for controlled external-route injection; it does not replace the OSPF backbone role. case-57 tests ospf-backbone-area: identify the OSPF backbone used to connect normal nonbackbone areas. case-57 remains protocol-specific.
2. the highest-numbered area does not fit. OSPF does not elect a backbone from the numerically highest area ID; Area 0 has the defined backbone function. case-58 tests ospf-backbone-area: identify the OSPF backbone used to connect normal nonbackbone areas. case-58 remains protocol-specific.
3. Area 0 is correct. Area 0 is the OSPF backbone. Area Border Routers connect other areas to the backbone so inter-area topology and summary information can be exchanged through the hierarchical design. case-59 tests ospf-backbone-area: identify the OSPF backbone used to connect normal nonbackbone areas. case-59 remains protocol-specific.
4. a totally stub area does not fit. A totally stub area intentionally limits summary and external information and cannot serve as the general backbone for other areas. case-60 tests ospf-backbone-area: identify the OSPF backbone used to connect normal nonbackbone areas. case-60 remains protocol-specific.

 

Question 16

A router has interfaces in Area 0 and Area 20 and exchanges reachability between those areas. What OSPF role does that router perform? Choose ONE.

1. Area Border Router (ABR)
2. Autonomous System Boundary Router (ASBR)
3. Designated Router (DR) only
4. EIGRP stub router

Correct Answer(s)

 

A

Rationale

20. Area Border Router (ABR) is correct. An ABR participates in more than one OSPF area and provides the boundary between the backbone and a nonbackbone area. That is the role described by interfaces in both Area 0 and Area 20. case-61 tests ospf-router-role: map a router connected to multiple OSPF areas including the backbone to its role. case-61 remains protocol-specific.
21. Autonomous System Boundary Router (ASBR) does not fit. An ASBR is defined by injecting external routing information into OSPF, not simply by attaching to two OSPF areas. case-62 tests ospf-router-role: map a router connected to multiple OSPF areas including the backbone to its role. case-62 remains protocol-specific.
22. Designated Router (DR) only does not fit. A DR is elected on certain multiaccess segments to reduce adjacencies; DR status does not describe inter-area boundary responsibility. case-63 tests ospf-router-role: map a router connected to multiple OSPF areas including the backbone to its role. case-63 remains protocol-specific.
23. EIGRP stub router does not fit. EIGRP stub is a different protocol concept and does not identify an OSPF router spanning Area 0 and another area. case-64 tests ospf-router-role: map a router connected to multiple OSPF areas including the backbone to its role. case-64 remains protocol-specific.

 

Question 17

A router redistributes routes from another routing domain into OSPF. Which OSPF role does it assume by performing that function? Choose ONE.

1. Area Border Router (ABR) by definition
2. Autonomous System Boundary Router (ASBR)
3. Backup Designated Router (BDR)
4. internal router only

Correct Answer(s)

 

B

Rationale

1. Area Border Router (ABR) by definition does not fit. ABR status depends on area attachment, not on redistribution; an ASBR may or may not also connect multiple areas. case-65 tests ospf-external-role: identify the OSPF router role that originates external reachability through redistribution. case-65 remains protocol-specific.
2. Autonomous System Boundary Router (ASBR) is correct. A router that redistributes non-OSPF reachability into the OSPF domain acts as an ASBR. The defining behavior is external route injection, regardless of whether that router also happens to be an ABR. case-66 tests ospf-external-role: identify the OSPF router role that originates external reachability through redistribution. case-66 remains protocol-specific.
3. Backup Designated Router (BDR) does not fit. BDR is a multiaccess-network adjacency role and does not describe origination of redistributed external routes. case-67 tests ospf-external-role: identify the OSPF router role that originates external reachability through redistribution. case-67 remains protocol-specific.
4. internal router only does not fit. An internal router has all OSPF interfaces in one area and, by this scenario, does not capture the external-redistribution role being exercised. case-68 tests ospf-external-role: identify the OSPF router role that originates external reachability through redistribution. case-68 remains protocol-specific.

 

Question 18

A router learns 192.0.2.0/24 as an OSPF intra-area route and also receives an inter-area path to the same prefix. Assuming both are valid, which route class is preferred? Choose ONE.

1. the inter-area route
2. the route with the larger area ID
3. OSPF always installs both regardless of route class
4. the intra-area route

Correct Answer(s)

 

D

Rationale

1. the inter-area route does not fit. Inter-area reachability is lower in OSPF’s route-type preference than a valid intra-area route to the same destination. case-69 tests ospf-route-type-preference: apply OSPF’s preference for intra-area reachability over inter-area reachability. case-69 remains protocol-specific.
2. the route with the larger area ID does not fit. Area numbering does not create a preference rule in which larger area IDs beat intra-area reachability. case-70 tests ospf-route-type-preference: apply OSPF’s preference for intra-area reachability over inter-area reachability. case-70 remains protocol-specific.
3. OSPF always installs both regardless of route class does not fit. Equal-cost multipath applies within comparable route types and metrics; different OSPF route classes are not automatically co-installed. case-71 tests ospf-route-type-preference: apply OSPF’s preference for intra-area reachability over inter-area reachability. case-71 remains protocol-specific.
4. the intra-area route is correct. OSPF prefers intra-area routes over inter-area routes for the same destination before comparing lower-priority external classes. The route learned within the local area therefore wins over an O IA alternative. case-72 tests ospf-route-type-preference: apply OSPF’s preference for intra-area reachability over inter-area reachability. case-72 remains protocol-specific.

 

Question 19

An ASBR advertises an external prefix as OSPF E1 instead of E2. What is the key metric behavior of E1? Choose ONE.

1. only the external metric is considered and internal cost is ignored
2. the route becomes intra-area
3. the metric is replaced by EIGRP feasible distance
4. the internal OSPF cost to reach the ASBR is added to the external metric

Correct Answer(s)

 

D

Rationale

1. only the external metric is considered and internal cost is ignored does not fit. That description matches the primary behavior of an E2 metric, not E1’s additive treatment of internal OSPF cost. case-73 tests ospf-external-metric-type: distinguish Type 1 external metric calculation from Type 2 behavior. case-73 remains protocol-specific.
2. the route becomes intra-area does not fit. Changing an external route from E2 to E1 does not change its classification into an internal OSPF route. case-74 tests ospf-external-metric-type: distinguish Type 1 external metric calculation from Type 2 behavior. case-74 remains protocol-specific.
3. the metric is replaced by EIGRP feasible distance does not fit. EIGRP feasible distance is unrelated to OSPF external route metric types and is not imported as the OSPF path metric. case-75 tests ospf-external-metric-type: distinguish Type 1 external metric calculation from Type 2 behavior. case-75 remains protocol-specific.
4. the internal OSPF cost to reach the ASBR is added to the external metric is correct. An OSPF E1 route combines the external metric with the internal OSPF cost needed to reach the advertising ASBR. This allows the location of the exit point inside the OSPF domain to influence the final metric. case-76 tests ospf-external-metric-type: distinguish Type 1 external metric calculation from Type 2 behavior. case-76 remains protocol-specific.

 

Question 20

A router inside an OSPF NSSA redistributes an external route. Which advertisement is used inside the NSSA before an ABR can translate it for the rest of the OSPF domain? Choose ONE.

1. Type 5 LSA directly throughout the NSSA
2. Type 7 LSA
3. Type 1 router LSA only
4. Type 3 summary LSA generated by the ASBR

Correct Answer(s)

 

B

Rationale

1. Type 5 LSA directly throughout the NSSA does not fit. Type 5 external LSAs are not flooded into an NSSA; the area uses Type 7 LSAs for locally originated external information. case-77 tests ospf-nssa-lsa: identify the LSA type used for external information originated inside an NSSA. case-77 remains protocol-specific.
2. Type 7 LSA is correct. An NSSA ASBR originates external information as a Type 7 LSA. An NSSA ABR can translate eligible Type 7 information into Type 5 for propagation outside the NSSA. case-78 tests ospf-nssa-lsa: identify the LSA type used for external information originated inside an NSSA. case-78 remains protocol-specific.
3. Type 1 router LSA only does not fit. Type 1 LSAs describe router links within an area but do not replace the special NSSA external advertisement format. case-79 tests ospf-nssa-lsa: identify the LSA type used for external information originated inside an NSSA. case-79 remains protocol-specific.
4. Type 3 summary LSA generated by the ASBR does not fit. Type 3 LSAs are summary advertisements associated with ABR inter-area reachability, not the NSSA external route originated by an ASBR. case-80 tests ospf-nssa-lsa: identify the LSA type used for external information originated inside an NSSA. case-80 remains protocol-specific.

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• Cisco CCNP 350-401 ENCOR EIGRP and OSPF Concepts, Metrics, Areas, and Path Operations Practice Test 2 >