JNCIP-ENT Interior Gateway Protocols Practice Test 2 — 15 Questions

Question 1

Which THREE parameters must match between OSPF routers for an adjacency to successfully form on a point-to-point network? (Choose three)

Accepted Answer

Authentication parameters. For OSPF neighbors to form adjacencies, area ID, hello/dead intervals, and authentication settings (if enabled) must match. MTU size can also cause stuck in ExStart/Exchange if mismatched and enabled.

Answer

Interface IP address subnets

Answer

Router ID

Question 2

An engineer needs to prevent Type-5 LSAs from entering an OSPF stub area while still allowing external routes to be reached via a default route. Which configuration statement under [edit protocols ospf area] achieves this on a Juniper device?

Accepted Answer

set stub. Configuring 'stub' without the 'no-summaries' keyword makes the area a standard stub area, which blocks Type-5 LSAs and injects a default route (Type-3 summary default).

Answer

set totally-stubby

Answer

set stub default-metric 10

Answer

set nssa default-lsa type-7

Question 3

You want to filter OSPF Type-3 Summary LSAs leaving Area 1 on an ABR running Junos OS. Where must this export policy be applied?

Accepted Answer

Under [edit protocols ospf area area-range export]. To filter Type-3 summary LSAs generated by an ABR as they leave an area, you apply the export policy using the 'set protocols ospf area area-range export ' hierarchy.

Answer

Under [edit protocols ospf area <name> prefix-export]

Answer

Under [edit protocols ospf lsa-filter]

Answer

Under [edit protocols ospf export]

Question 4

An engineer is configuring OSPFv3 on Junos OS and notices that adjacencies are failing to form over a point-to-point link. Reviewing the interface configuration, what is a mandatory requirement for OSPFv3 interface configuration that differs fundamentally from OSPFv2?

Accepted Answer

Enabling the interface with an IPv6 link-local address for neighbor discovery.. OSPFv3 relies heavily on IPv6 link-local addresses for neighbor discovery and next-hop resolution, and interfaces must have an IPv6 link-local address assigned.

Answer

Disabling IPv6 stateless address autoconfiguration (SLAAC) on the underlying physical interface.

Answer

Explicit manual configuration of the Router ID using the global router-id statement.

Answer

Defining explicit neighbor statements using the neighbor command for all point-to-point links.

Question 5

You are designing a routing policy to tag routes being redistributed from OSPF into BGP. Where in the routing policy should the tag match condition be placed?

Accepted Answer

from ospf-tag <value>. When matching OSPF route tags in routing policies, the term must include the 'ospf-tag' match condition within the 'from' block.

Answer

from protocol ospf tag <value>

Answer

from route-tag <value>

Answer

term match-tag value <value>

Question 6

Which THREE parameters must match between two OSPF routers on a shared broadcast segment for an adjacency to successfully form? (Choose three)

Accepted Answer

Router ID. For an OSPF adjacency to form on a shared broadcast segment, the Area ID (Option B) must match because OSPF routers only become neighbors within the same OSPF area — a mismatch in Area ID prevents the Hello from being accepted and the adjacency stays down. The Hello and Dead interval timers (Option C) must also match, since OSPF Hello packets carry these values and a mismatch causes the routers to reject each other's Hellos, preventing the neighbor relationship from progressing past INIT. The Router ID (Option A) must be unique and is used to identify each router in the OSPF domain; on a broadcast segment, duplicate Router IDs cause adjacency formation to fail because OSPF cannot distinguish the routers, and the Router ID is carried in Hello packets and checked during neighbor establishment. Interface MTU size (Option D) does not have to match for an adjacency to reach the 2-Way or even ExStart state, though a mismatch can prevent the database exchange from completing (it is checked in DBD packets, not Hello packets). The Interface primary IP address subnet (Option E) does not need to match for OSPF adjacency formation on a broadcast segment, because OSPF uses multicast Hellos and the routers can still form a neighbor relationship even if their IP addresses are on different subnets, as long as the Layer 2 connectivity exists.

Answer

Interface MTU size

Answer

Interface primary IP address subnet

Question 7

Which TWO actions can you take in Junos OS to optimize OSPF convergence times in a large enterprise network? (Choose two)

Accepted Answer

Configure faster Hello and Dead intervals on transit interfaces.. OSPF convergence can be accelerated by tuning SPF schedule delays (spf-options) and adjusting interface-specific hello and dead intervals.

Answer

Disable link-state acknowledgement pacing globally.

Answer

Convert all backbone areas into completely stubby areas.

Answer

Increase the SPF hold-down timer to allow network stabilization before running computations.

Question 8

You are the network architect for a large enterprise running OSPF in a single area. The network has grown to over 200 routers, and you notice that the link-state database (LSDB) is large and SPF calculations are becoming frequent. You want to reduce the size of the LSDB and limit the scope of topology changes without introducing multiple areas. Which Junos OS feature should you implement?

Accepted Answer

OSPF flood reduction. OSPF flood reduction is designed for large single-area OSPF networks. It allows a router to filter LSAs received from a neighbor on a point-to-point link, reducing the LSDB size and limiting the scope of topology changes. This directly addresses the symptoms of a large LSDB and frequent SPF calculations without the complexity of multiple areas.

Answer

OSPF LSA refresh reduction

Answer

OSPF stub area

Answer

OSPF demand circuits

Question 9

You are deploying OSPF in a Junos OS environment where several routers connect to a shared Layer 2 segment through a non-broadcast WAN. The segment does not support multicast or broadcast, and you need to form OSPF adjacencies without manually configuring each neighbor. Which OSPF interface type should you configure on the Junos routers?

Accepted Answer

p2mp. The p2mp interface type is designed for non-broadcast multi-access segments where multicast is unavailable but dynamic neighbor discovery is still desired. It uses multicast Hellos and treats the segment as a set of point-to-point links, eliminating the need for manual neighbor statements. This makes it the correct choice for forming OSPF adjacencies automatically on such a WAN.

Answer

broadcast

Answer

nbma

Answer

p2p

Question 10

You are deploying OSPFv3 in a dual-stack Juniper Networks environment. You need to ensure that IPv6 prefix information is propagated within a single area without requiring a separate area for each prefix. Which TWO OSPFv3 LSA types are used to carry IPv6 prefix information within an area? (Choose two.)

Accepted Answer

Intra-Area-Prefix-LSA (Type 0x2009). OSPFv3 separates prefix information from router and network LSAs. The Intra-Area-Prefix-LSA (Type 0x2009) is used to advertise IPv6 prefixes within the same area, associating them with a router or network LSA. The Inter-Area-Prefix-LSA (Type 0x2003) is used by ABRs to advertise prefixes from other areas into the local area. Together, these two LSA types carry IPv6 prefix information for intra-area and inter-area reachability, respectively.

Answer

Link-LSA (Type 0x2008)

Answer

Router-LSA (Type 0x2001)

Answer

Network-LSA (Type 0x2002)

Question 11

You are troubleshooting an OSPF adjacency that remains in ExStart state on a Junos router. The interface is a Gigabit Ethernet link with a default MTU of 1500 bytes. Which configuration change is most likely to resolve the issue?

Accepted Answer

Configure the ignore-mtu-mismatch statement under the OSPF interface.. An OSPF adjacency stuck in ExStart is commonly caused by an MTU mismatch between the two routers. The ignore-mtu-mismatch statement under the OSPF interface configuration allows the routers to skip MTU checking during Database Description exchange, enabling the adjacency to progress to Exchange and Full. This is the correct resolution when you cannot or do not want to change the actual MTU.

Answer

Set the OSPF interface type to p2p on both routers.

Answer

Change the OSPF hello interval to 10 seconds on both routers.

Answer

Set the interface MTU to 1500 on both routers.

Question 12

You are deploying OSPF in a Juniper EX Series switch stack that connects to a service provider. The provider requires that your OSPF process not send any external LSAs into the provider's area, and that your internal routers not receive external LSAs from the provider. You need to configure the OSPF area on your edge router to prevent Type-5 LSAs from being flooded into the area. Which OSPF area type should you configure?

Accepted Answer

Stub area. A stub area prevents Type-5 external LSAs from entering, which exactly matches the need to isolate internal routers from external LSAs. The ABR generates a default route to maintain connectivity. Other area types either allow external LSAs or block additional LSA types unnecessarily.

Answer

Totally stubby area

Answer

Backbone area

Answer

Not-so-stubby area (NSSA)

Question 13

You are configuring OSPF on a Juniper Networks router. You want to ensure that the router never becomes the designated router (DR) on a broadcast network, but it can still become the backup designated router (BDR). Which configuration statement accomplishes this?

Accepted Answer

set protocols ospf area 0 interface ge-0/0/0.0 priority 0. In OSPF, the interface priority determines DR/BDR election. A priority of 0 makes the router ineligible to become DR or BDR. To ensure a router never becomes DR, setting priority to 0 is the correct configuration. Other priorities do not prevent DR election; they only influence the likelihood. Therefore, the correct statement is to set the priority to 0.

Answer

set protocols ospf area 0 interface ge-0/0/0.0 priority 1

Answer

set protocols ospf area 0 interface ge-0/0/0.0 priority 100

Answer

set protocols ospf area 0 interface ge-0/0/0.0 priority 255

Question 14

You are configuring OSPFv3 on a Juniper SRX Series firewall to support IPv6 routing. You need to enable OSPFv3 on an interface and ensure that it participates in the correct area. Which two configuration steps are required to enable OSPFv3 on a specific interface in Junos? (Choose two.)

Accepted Answer

Assign an IPv6 address to the interface.. To enable OSPFv3 on an interface, you must configure the interface under the OSPFv3 area hierarchy and ensure the interface has IPv6 enabled, typically via an IPv6 address. These two steps allow the interface to form adjacencies and participate in OSPFv3. Other steps like router ID are global and not interface-specific.

Answer

Configure an OSPFv3 router ID.

Answer

Set the OSPFv3 interface type to point-to-point.

Answer

Enable OSPFv3 globally with the [edit protocols ospf3] statement.

Question 15

You are configuring an OSPF NSSA on a Juniper Networks router. You want to prevent the ABR from translating Type-7 LSAs into Type-5 LSAs because another ABR is already performing the translation. Which configuration statement should you use?

Accepted Answer

set protocols ospf area 1 nssa translator-role never. In an NSSA, Type-7 LSAs are translated to Type-5 by the NSSA ABR with the highest router ID, unless configured otherwise. To prevent an ABR from translating, you set its translator role to 'never'. This is done with the 'translator-role never' statement under the NSSA area configuration. This ensures that only the intended ABR performs translation, preventing duplicate Type-5 LSAs and potential routing loops.

Answer

set protocols ospf area 1 nssa translate-role never

Answer

set protocols ospf area 1 nssa no-translations

Answer

set protocols ospf area 1 nssa no-summaries