JNCIP-ENT Interior Gateway Protocols Practice Test 4 — 15 Questions

Question 1

You need to adjust the OSPF cost on a specific interface to manipulate path selection. Which command sets the OSPF cost on an interface?

Accepted Answer

set protocols ospf area 0.0.0.0 interface xe-0/0/0.0 cost 50. OSPF interface cost is explicitly configured under the interface hierarchy within protocols ospf using the 'cost' statement.

Answer

set routing-options interface xe-0/0/0.0 ospf-cost 50

Answer

set interfaces xe-0/0/0.0 ospf-cost 50

Answer

set protocols ospf area 0.0.0.0 interface xe-0/0/0.0 metric 50

Question 2

You are configuring OSPF database overflow protection to prevent a router from running out of memory due to an excessive number of external LSAs in the LSDB. Which configuration enables this feature globally?

Accepted Answer

set protocols ospf database-overflow limit 5000 external-timer 300. Database overflow protection in Junos OSPF is configured using the 'database-overflow' statement under protocols ospf, specifying the limit and external timer.

Answer

set protocols ospf max-external-lsas 5000

Answer

set protocols ospf area 0.0.0.0 overflow-limit 5000

Answer

set routing-options ospf overflow-protection limit 5000

Question 3

Which TWO actions can be performed by an OSPF routing policy export filter when redistributing routes into OSPF? (Choose two)

Accepted Answer

Modify the OSPF route metric using the metric action.. Routing policies when exporting into OSPF can set metric types (Type 1 or Type 2) and modify route metrics. They cannot directly change area ID during redistribution without area design changes.

Answer

Change the OSPF hello timer interval via routing policy.

Answer

Alter the OSPF router ID of neighboring routers.

Answer

Change the OSPF area ID of external routes dynamically.

Question 4

Which THREE types of LSAs are blocked from entering an OSPF Totally Stubby Area? (Choose three)

Accepted Answer

Type 4 ASBR Summary LSAs. Totally stubby areas block summary LSAs (Type 3), ASBR summary LSAs (Type 4), and AS external LSAs (Type 5). Router (Type 1) and Network (Type 2) LSAs are allowed within the area.

Answer

Type 1 Router LSAs

Answer

Type 2 Network LSAs

Question 5

When configuring OSPF sham-links in Junos to support MPLS VPN back-door links, which TWO characteristics apply? (Choose two)

Accepted Answer

Sham-links are configured as point-to-point links between PE router loopback addresses within the VPN routing instance.. Sham-links are treated as intra-area links between PE routers and require a separate /32 IP address configured under the loopback or routing instance, appearing as unnumbered or numbered point-to-point links.

Answer

Sham-links are advertised as Type-5 external LSAs across the network.

Answer

Sham-links require physical interfaces dedicated solely to the backdoor connection.

Answer

Sham-links are only supported in OSPFv3, not OSPFv2.

Question 6

Which TWO commands are used to troubleshoot OSPF issues on Junos devices? (Choose two)

Accepted Answer

show ospf neighbor. Operational commands like 'show ospf neighbor' and 'show ospf database' are standard for troubleshooting OSPF adjacencies and LSDB status.

Answer

show ip ospf interface

Answer

show protocols ospf status

Answer

show route ospf-table

Question 7

Which TWO types of OSPF areas allow the generation of Type-7 LSAs? (Choose two)

Accepted Answer

Not-So-Stubby Area (NSSA). Option B (Not-So-Stubby Area, NSSA) is correct because an NSSA is defined as a stub area that can import external routes via an Autonomous System Boundary Router (ASBR), and those external routes are flooded within the area as Type-7 LSAs (NSSA External LSAs). Option D (NSSA Totally Stubby Area) is also correct because it is simply an NSSA variant that additionally blocks Type-3 and Type-4 summary LSAs from the backbone, but it still permits an ASBR and therefore still generates Type-7 LSAs for redistributed external routes. Option A (Standard OSPF Non-backbone Area) is incorrect because a normal non-backbone area uses Type-5 LSAs for external routes, not Type-7. Option C (Standard OSPF Backbone Area, Area 0) is incorrect because the backbone is a standard area that floods external routes as Type-5 LSAs and never uses Type-7. Option E (OSPF Stub Area) is incorrect because a stub area does not allow an ASBR or external route redistribution, so no Type-7 LSAs can be generated there.

Answer

Standard OSPF Non-backbone Area

Answer

Standard OSPF Backbone Area (Area 0)

Answer

OSPF Stub Area

Question 8

Which THREE mechanisms are utilized by Junos to protect OSPF routing operations and control plane resources? (Choose three)

Accepted Answer

OSPF cryptographic authentication (MD5 or keychain-based authentication). Control plane protection for OSPF includes Routing Engine firewall filters (lo0 filters), OSPF cryptographic authentication (MD5/SHA), and OSPF graceful restart helper mode / overload control.

Answer

Strict TCP handshake validation for OSPF hello packets

Answer

IPsec tunnel encapsulation mandatory for all intra-area OSPFv2 packets

Question 9

Which THREE configuration tasks are required when implementing OSPFv3 on Junos devices? (Choose three)

Accepted Answer

Enabling OSPFv3 under the protocols ospf3 hierarchy. Configuring OSPFv3 requires specifying protocols ospf3, configuring areas, and enabling OSPFv3 on specific interfaces (IPv6 enabled).

Answer

Configuring BGP autonomous system numbers for OSPFv3 operation

Answer

Enabling IPv4 address families inside protocols ospf3

Question 10

You are redistributing BGP routes into OSPF on an MX Series router. By default, what metric type and cost are assigned to these redistributed routes when they enter the OSPF domain?

Accepted Answer

Metric-type 2 with a cost of 1. By default, routes redistributed into OSPF are assigned metric-type 2 (E2) and a default metric value of 1.

Answer

Metric-type 1 with a cost of 20

Answer

Metric-type 1 with a cost of 0

Answer

Metric-type 2 with a cost of 10

Question 11

Which OSPFv3 LSA type is responsible for carrying IPv6 prefix information within the same area, replacing the role of Router and Network LSAs carrying IP addresses in OSPFv2?

Accepted Answer

Type 9 (Intra-Area-Prefix LSA). OSPFv3 separates topology information from IP prefix information. Type-9 (Intra-Area-Prefix-LSA) carries IPv6 prefixes associated with routers or transit networks within the area.

Answer

Type 1 (Router LSA)

Answer

Type 5 (AS-External LSA)

Answer

Type 3 (Inter-Area-Prefix LSA)

Question 12

Which Junos configuration hierarchy is used to disable the generation of OSPF Type-7 to Type-5 LSA translation on an NSSA Area Border Router (ABR)?

Accepted Answer

set protocols ospf area nssa translator-role never. To prevent an NSSA ABR from translating Type-7 LSAs into Type-5 LSAs, you use the 'no-summaries' or 'nssa translator never' commands. Specifically, disabling translation is done via 'set protocols ospf area nssa translator-role never'.

Answer

set protocols ospf area <name> stub no-translate

Answer

set protocols ospf translate-type7 off

Answer

set protocols ospf area <name> nssa no-translation

Question 13

Which TWO statements are correct regarding OSPF NSSA (Not-So-Stubby Area) behavior and configuration in Junos OS? (Choose two)

Accepted Answer

NSSAs allow the injection of external routes into the area using Type-7 LSAs.. NSSA areas allow external routes to be injected via Type-7 LSAs. By default, an NSSA does not flood default routes unless explicitly configured with 'default-lsa'.

Answer

Virtual links are fully supported to transit across an NSSA area.

Answer

An NSSA ABR automatically floods a default summary route into the NSSA by default.

Answer

NSSAs fully support external Type-5 LSAs originating from normal areas directly within the NSSA.

Question 14

You are troubleshooting an OSPF adjacency between two Juniper Networks routers on a broadcast Ethernet segment. The routers are in the same area and have matching hello and dead intervals. The adjacency remains in ExStart state. Which OSPF parameter mismatch is the most likely cause?

Accepted Answer

MTU mismatch. OSPF adjacency formation progresses through Down, Init, 2-Way, ExStart, Exchange, Loading, and Full. A stall in ExStart indicates that the routers cannot agree on the master/slave relationship and initial sequence number for database description packets. The most common cause is an MTU mismatch, because the router with the larger MTU may send packets that the other router cannot process, or the DBD packets are rejected. Matching MTU or using the 'ignore-mtu' statement resolves the issue.

Answer

Authentication mismatch

Answer

Area ID mismatch

Answer

Hello interval mismatch

Question 15

You manage a Juniper Networks enterprise network using OSPF. Router R1 and Router R2 are connected via a point-to-point link. R1 is configured with the interface ge-0/0/0.0 in area 0 with a hello interval of 10 seconds and a dead interval of 40 seconds. R2 has the same interface in area 0 but with a hello interval of 30 seconds and a dead interval of 120 seconds. After configuration, the OSPF adjacency does not form. Which action will resolve the issue?

Accepted Answer

Change the hello interval on R1 to 30 seconds and the dead interval to 120 seconds.. OSPF requires that the hello and dead intervals match on both routers for an adjacency to form. In this scenario, R1 has hello 10 and dead 40, while R2 has hello 30 and dead 120. Changing R1's timers to match R2's will allow the adjacency to establish. The other options would not resolve the timer mismatch and could introduce additional issues.

Answer

Change the OSPF router ID on R1 to be higher than R2's router ID.

Answer

Change the network type on R1 to non-broadcast.

Answer

Change the OSPF area on R1 to area 1.