JNCIP-ENT Interior Gateway Protocols — 20 Questions

Question 1

You want to tune OSPF convergence by reducing the hello and dead intervals on a point-to-point interface. Which configuration is valid?

Accepted Answer

set protocols ospf area 0.0.0.0 interface xe-0/0/0.1 hello-interval 1. OSPF interface timers such as hello-interval and dead-interval are configured directly under the interface hierarchy within protocols ospf.

Answer

set protocols ospf area 0.0.0.0 timers hello-interval 1

Answer

set interfaces xe-0/0/0.1 ospf hello-interval 1

Answer

set protocols ospf hello-interval 1 dead-interval 4

Question 2

You are redistributing static routes into OSPF on a Junos device and want to assign a specific metric type to the resulting External LSAs. Where is this metric-type defined?

Accepted Answer

set policy-options policy-statement REDIST-STATIC term 1 then metric-type type-1. External route metric types (Type 1 or Type 2) when redistributing into OSPF are defined under the export policy term's then clause using 'metric-type'.

Answer

set policy-options policy-statement REDIST-STATIC term 1 from external-type 1

Answer

set protocols ospf export REDIST-STATIC metric-type 1

Answer

set protocols ospf redistribute static metric-type 1

Question 3

An OSPF area in your network contains multiple ABRs. You need to suppress the generation of Type-4 summary LSAs into a totally stubby area. How does Junos handle this natively?

Accepted Answer

Totally stubby areas automatically block Type-4 LSAs by design without additional configuration.. Totally stubby areas automatically block Type-3, Type-4, and Type-5 LSAs. No separate command is needed to suppress Type-4 LSAs once an area is defined as a totally stubby area.

Answer

You must apply an export policy on the ABR blocking Type-4 LSAs.

Answer

You must use set protocols ospf suppress-fa to remove Type-4 LSAs.

Answer

You must configure set protocols ospf area <area> stub no-summary-asbr.

Question 4

You need to configure OSPFv2 graceful restart as a helper on a Junos router to assist neighboring routers during their routing engine switchover. Which command enables helper mode?

Accepted Answer

set protocols ospf graceful-restart helper. By default, OSPF graceful restart helper mode is enabled on Junos routers. To explicitly configure or modify it, you use the 'graceful-restart helper' command under protocols ospf.

Answer

set routing-options graceful-restart ospf helper

Answer

set protocols ospf graceful-restart router-role helper

Answer

set protocols ospf helper-mode enable

Question 5

When configuring OSPFv3 authentication, which mechanism is natively utilized in modern Junos implementations since OSPFv3 relies on IPv6 AH/ESP or OSPFv3 Authentication Trailer (RFC 7166)?

Accepted Answer

set protocols ospf3 authentication-trailers sa-name AUTH-KEY. Junos supports the OSPFv3 Authentication Trailer defined in RFC 7166, configured via the authentication-trailers command under protocols ospf3.

Answer

set protocols ospf3 area 0.0.0.0 interface xe-0/0/0.0 md5 key 123

Answer

set protocols ospf3 security ipsec spi 256

Answer

set protocols ospf3 interface xe-0/0/0.0 password 123

Question 6

You need to ensure that an OSPF interface does not send or receive OSPF hellos, but its subnet is still advertised into the OSPF domain. What configuration achieves this in Junos?

Accepted Answer

set protocols ospf area 0.0.0.0 interface em0.0 passive. Configuring an interface as passive prevents OSPF protocol packets from being sent or received on that interface while still including its network prefix in the routing updates.

Answer

set protocols ospf area 0.0.0.0 interface em0.0 silent

Answer

set protocols ospf passive-interface em0.0

Answer

set protocols ospf area 0.0.0.0 interface em0.0 disable-hellos

Question 7

You are configuring OSPF domain-id when redistributing routes between OSPF and BGP (or multiarea setups). Which configuration statement sets the OSPF domain identifier?

Accepted Answer

set protocols ospf domain-id 10.0.0.1. The domain-identifier for OSPF (often used in MPLS VPNs or inter-AS scenarios) is configured under protocols ospf using the domain-id statement.

Answer

set protocols ospf area 0.0.0.0 domain-identifier 10.0.0.1

Answer

set routing-options autonomous-system 65000 ospf-domain 10.0.0.1

Answer

set protocols ospf bgp-domain-identifier 10.0.0.1

Question 8

You are troubleshooting an OSPF network where virtual links are deployed to connect a non-backbone area to Area 0 across a transit area. Which statement is true regarding virtual link configuration in Junos?

Accepted Answer

set protocols ospf area 0.0.0.1 virtual-link transit-area 0.0.0.2 neighbor-id 192.168.10.1. Virtual links require you to specify the area ID of the transit area and the router ID of the remote endpoint (the other ABR) under protocols ospf.

Answer

set protocols ospf area 0.0.0.2 transit-link neighbor 192.168.10.1

Answer

set protocols ospf virtual-link neighbor 192.168.10.1 area 0.0.0.1

Answer

set protocols ospf virtual-router 192.168.10.1 transit-area 0.0.0.2

Question 9

You are tasked with summarizing internal OSPF routes on an Area Border Router (ABR). Which configuration statement accomplishes route summarization for an area?

Accepted Answer

set protocols ospf area 0.0.0.1 area-range 10.10.0.0/16. Internal route summarization on an OSPF ABR in Junos is configured using the 'area-range' statement under the specific area hierarchy.

Answer

set protocols ospf summary 10.10.0.0/16 area 0.0.0.1

Answer

set protocols ospf area 0.0.0.1 aggregate 10.10.0.0/16

Answer

set routing-options aggregate route 10.10.0.0/16 ospf

Question 10

You need to prevent an OSPF interface from participating in Designated Router (DR) election, forcing it to always act as a DROTHER, even if it has the highest priority. How is this achieved in Junos?

Accepted Answer

set protocols ospf area 0.0.0.0 interface xe-0/0/0.0 no-dr-election. Setting the OSPF interface priority to 0 prevents the router from participating in DR/BDR elections and forces it to become a DROTHER.

Answer

set protocols ospf area 0.0.0.0 interface xe-0/0/0.0 disable-dr

Answer

set protocols ospf area 0.0.0.0 interface xe-0/0/0.0 drother-only

Question 11

You want to tune the speed at which OSPF processes link-state updates by modifying the SPF calculation delay and hold timers. Where are these timers configured?

Accepted Answer

set protocols ospf spf-delay 200 spf-holdtime 1000. SPF calculation timers (delay and hold) are configured under the protocols ospf hierarchy using the spf-delay and spf-holdtime statements.

Answer

set routing-options ospf spf-timers delay 200 hold 1000

Answer

set protocols ospf area 0.0.0.0 timers spf 200 1000

Answer

set protocols ospf interface xe-0/0/0.0 spf-timer 200

Question 12

Which command allows you to view the real-time tracing of OSPF packet exchanges and state changes on a Junos device?

Accepted Answer

set protocols ospf traceoptions file ospf-log size 10m files 5. OSPF tracing is configured and viewed using standard Junos traceoptions, and operational debugging is viewed using 'clear' or 'show log' or real-time tracing commands. For checking active traces or running traces, traceoptions are configured under protocols ospf.

Answer

set debug ospf packets enable

Answer

monitor protocols ospf debug

Answer

set system tracing ospf enable

Question 13

When redistributing BGP routes into OSPF, what is the default OSPF metric assigned to the redistributed routes in Junos if no metric is specified in the export policy?

Accepted Answer

A default metric of 5 is assigned.. When routes are redistributed into OSPF without an explicit metric set in the policy, Junos assigns a default metric of 5 for external routes.

Answer

A default metric of 10 is assigned.

Answer

A default metric of 0 is assigned.

Answer

A default metric of 20 is assigned.

Question 14

Which TWO attributes are required to establish an OSPF adjacency on a broadcast multi-access network? (Choose two)

Accepted Answer

Membership in the same OSPF area. To form an OSPF adjacency on a broadcast network, interfaces must share matching hello and dead intervals, and be in the same OSPF area. Subnet masks must match as well.

Answer

Identical OSPF reference bandwidths

Answer

Matching process IDs

Question 15

Which TWO statements are true regarding Junos OSPF routing policies and policy evaluation? (Choose two)

Accepted Answer

Policy terms are evaluated in sequential order from top to bottom.. Junos routing policies are evaluated top-to-bottom per term, and if no match is found, the default action depends on the context (reject for export policies, accept for import policies in some contexts, but let's review exact Junos behavior: export policies default to reject, import policies default to accept). Also, route filtering can match specific prefixes.

Answer

Routing policies cannot match route prefixes, only protocol types.

Answer

OSPF import policies evaluate routing updates before they enter the Junos forwarding table.

Answer

Policy evaluation stops immediately upon matching a 'next-term' action.

Question 16

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 17

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 18

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 19

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 20

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>