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JNCIE-SP practice questions

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Question 1System and Platform Configuration (Junos OS, user accounts, logging, NTP, SNMP, chassis/interface configuration, software upgrades)

On a Junos device, which configuration statement places the local user account 'netops' into the super-user login class while also assigning it an encrypted password hash?

  1. set system login user netops login-class root authentication password "$6$..."
  2. set system login class netops super-user authentication encrypted-password "$6$..."
  3. set system login user netops class super-user authentication encrypted-password "$6$..." Correct answer.
  4. set system login user netops permissions all authentication plain-text-password "$6$..."

Explanation

Junos places accounts under the [edit system login user <name>] hierarchy; the class statement assigns the login class (super-user) and authentication encrypted-password stores a pre-hashed value. The class name is a value of the class statement, not a hierarchy level of its own.

Question 2System and Platform Configuration (Junos OS, user accounts, logging, NTP, SNMP, chassis/interface configuration, software upgrades)

An operator wants Junos to authenticate logins against a RADIUS server but still allow the local 'root' account to log in if the server is unreachable. Which configuration accomplishes this?

  1. set system radius-server 10.0.0.5 secret junos; set system authentication-order password; set system root-authentication plain-text-password
  2. set system radius-server 10.0.0.5 secret junos; set system login class radius permissions all
  3. set system radius-server 10.0.0.5 secret junos; set system authentication-order radius
  4. set system radius-server 10.0.0.5 secret junos; set system authentication-order [ radius password ] Correct answer.

Explanation

authentication-order is an ordered list; listing radius before password makes RADIUS primary while password (the local database) remains a fallback. Root authentication must also be configured, but the ordering is what provides the fallback behavior.

Question 3System and Platform Configuration (Junos OS, user accounts, logging, NTP, SNMP, chassis/interface configuration, software upgrades)

Which statement about Junos commit confirmed is accurate?

  1. It commits the configuration but automatically rolls back unless confirmed within the timeout. Correct answer.
  2. It commits the configuration only after a second administrator approves it.
  3. It commits the configuration and prevents any further commits for the timeout period.
  4. It saves the candidate configuration to a rollback file before committing.

Explanation

commit confirmed applies the candidate configuration immediately and starts a timer (default 10 minutes); if the change is not confirmed with a commit before the timer expires, Junos reverts to the previous configuration. This protects remote administrators from locking themselves out.

Question 4System and Platform Configuration (Junos OS, user accounts, logging, NTP, SNMP, chassis/interface configuration, software upgrades)

You want interface ge-0/0/1 to come up administratively but remain without an assigned address while you stage the configuration. Which configuration achieves this?

  1. set interfaces ge-0/0/1 unit 0 family inet Correct answer.
  2. set interfaces ge-0/0/1 unit 0 family inet address 0.0.0.0/0
  3. set interfaces ge-0/0/1 mtu 0
  4. set interfaces ge-0/0/1 disable

Explanation

Configuring a logical unit with family inet but no address statement leaves the interface administratively enabled and up, with no IPv4 address assigned. The 'disable' statement instead administratively shuts the interface down.

Question 5System and Platform Configuration (Junos OS, user accounts, logging, NTP, SNMP, chassis/interface configuration, software upgrades)

Which command displays the current Junos software release and the uptime of the routing engine?

  1. show configuration | display set
  2. show version Correct answer.
  3. show chassis hardware
  4. show system uptime

Explanation

'show version' reports the Junos OS release, model, and routing engine uptime. 'show chassis hardware' lists hardware inventory, while 'show system uptime' shows time and load statistics.

Question 6System and Platform Configuration (Junos OS, user accounts, logging, NTP, SNMP, chassis/interface configuration, software upgrades)

A device must synchronize time from two internal NTP servers, 192.0.2.10 and 192.0.2.11, and must never accept time from any other source. Which configuration satisfies this?

  1. set system ntp server 192.0.2.10; set system ntp server 192.0.2.11; set system ntp authenticate
  2. set system ntp server 192.0.2.10; set system ntp server 192.0.2.11; set system ntp boot-server 192.0.2.10 Correct answer.
  3. set system ntp server 192.0.2.10; set system ntp server 192.0.2.11; set system ntp trusted-key 1
  4. set system ntp server 192.0.2.10 prefer; set system ntp server 192.0.2.11

Explanation

Junos only polls NTP servers explicitly configured under system ntp server; a boot-server is used for initial time at boot. Configuring the two servers restricts synchronization to them, and boot-server gives a startup source.

Question 7System and Platform Configuration (Junos OS, user accounts, logging, NTP, SNMP, chassis/interface configuration, software upgrades)

Which SNMP configuration allows a read-only community 'monitor' to be used from any source address?

  1. set snmp community monitor authorization read-only; set snmp community monitor clients 0.0.0.0/0 Correct answer.
  2. set snmp community monitor clients 0.0.0.0/0
  3. set snmp community monitor authorization read-only
  4. set snmp view monitor oid .1 include

Explanation

The community statement needs authorization read-only to permit GET operations, and clients 0.0.0.0/0 permits any source address. Both statements together produce the desired read-only, unrestricted community.

Question 8System and Platform Configuration (Junos OS, user accounts, logging, NTP, SNMP, chassis/interface configuration, software upgrades)

Which statement about Junos syslog facility configuration is correct?

  1. Facilities must be configured before any host can receive messages.
  2. Facilities are optional tags that group messages by source subsystem and route them to destinations. Correct answer.
  3. Facilities map to syslog severities and determine which messages are written to a destination.
  4. Facilities only apply to messages generated by the kernel.

Explanation

In Junos, facility names such as any, kernel, daemon, and interactive-commands act as filters that select messages by originating subsystem, and each facility is associated with one or more destinations (file, host, console). Severities are specified separately within each destination.

Question 9System and Platform Configuration (Junos OS, user accounts, logging, NTP, SNMP, chassis/interface configuration, software upgrades)

A new Junos image has been uploaded to /var/tmp. Which command validates the image and installs it into the alternate partition?

  1. request system reboot /var/tmp/junos-sp.tgz
  2. request system software add /var/tmp/junos-sp.tgz no-validate
  3. request system software delete /var/tmp/junos-sp.tgz
  4. request system software add /var/tmp/junos-sp.tgz validate Correct answer.

Explanation

'request system software add <package> validate' checks the package checksum and compatibility before installing it to the alternate partition. The device continues running the current image until a reboot.

Question 10System and Platform Configuration (Junos OS, user accounts, logging, NTP, SNMP, chassis/interface configuration, software upgrades)

After installing a new Junos release, which command makes the device boot from the newly installed partition?

  1. request system reboot Correct answer.
  2. request system snapshot
  3. request system software rollback
  4. request system zeroize

Explanation

Installing software writes to the alternate partition, but the running image stays active until the device reboots. 'request system reboot' restarts the routing engine using the newly installed partition.

Question 11System and Platform Configuration (Junos OS, user accounts, logging, NTP, SNMP, chassis/interface configuration, software upgrades)

Which configuration restricts SSH management access on fxp0 to the 198.51.100.0/24 subnet?

  1. set system services ssh root-login deny
  2. set system services ssh; set firewall family inet filter mgmt term ssh from source-address 198.51.100.0/24; set firewall family inet filter mgmt term ssh then accept; set interfaces fxp0 unit 0 family inet filter input mgmt Correct answer.
  3. set interfaces fxp0 unit 0 family inet address 198.51.100.1/24
  4. set system services ssh connection-limit 5

Explanation

A stateless firewall filter applied as an input filter on fxp0 can match source-address and accept only the permitted subnet, dropping all other traffic. The SSH service must also be enabled for permitted hosts to connect.

Question 12System and Platform Configuration (Junos OS, user accounts, logging, NTP, SNMP, chassis/interface configuration, software upgrades)

Which command shows the rescue configuration and confirms whether one is set?

  1. show system rollback 0
  2. show system commit
  3. show system configuration rescue Correct answer.
  4. show configuration | compare rollback 1

Explanation

'show system configuration rescue' displays the saved rescue configuration if one exists. The rescue configuration is a known-good baseline that can be restored with 'rollback rescue'.

Question 13System and Platform Configuration (Junos OS, user accounts, logging, NTP, SNMP, chassis/interface configuration, software upgrades)

A Junos device must send SNMP traps to a manager at 203.0.113.20 using SNMPv2c with community 'trapcom'. Which configuration is required?

  1. set snmp community trapcom clients 203.0.113.20; set snmp trap-group tg targets 203.0.113.20; set snmp trap-group tg version v2 Correct answer.
  2. set snmp trap-group tg targets 203.0.113.20; set snmp trap-group tg version v2
  3. set snmp trap-group tg targets 203.0.113.20; set snmp trap-group tg version v3
  4. set snmp community trapcom authorization read-only; set snmp trap-group tg targets 203.0.113.20; set snmp trap-group tg version v2

Explanation

Traps require a trap-group with targets and a version, and SNMPv2c traps are sent using a community that permits access. The clients statement authorizes the manager address for that community.

Question 14System and Platform Configuration (Junos OS, user accounts, logging, NTP, SNMP, chassis/interface configuration, software upgrades)

Which statement correctly describes how Junos handles a commit when the configuration contains a syntax error?

  1. The commit succeeds but only applies the valid portions of the configuration.
  2. The commit succeeds and logs a warning about the error.
  3. The commit fails and the candidate configuration remains unchanged on the device. Correct answer.
  4. The commit fails and the device automatically rolls back to the factory default.

Explanation

Junos validates the entire candidate configuration before committing; a syntax or semantic error causes the commit to fail and the candidate remains in place for correction. Junos never partially applies a configuration.

Question 15System and Platform Configuration (Junos OS, user accounts, logging, NTP, SNMP, chassis/interface configuration, software upgrades)

Which configuration creates a custom login class 'helpdesk' that permits only the 'clear' and 'view' commands?

  1. set system login user helpdesk class helpdesk allow-commands "clear|view"
  2. set system login class helpdesk allow-commands "clear|view" Correct answer.
  3. set system login class helpdesk deny-commands "clear|view"
  4. set system login class helpdesk permissions clear view

Explanation

The allow-commands statement takes a regular expression that whitelists permitted operational commands. With allow-commands set, all other commands are denied for members of that class.

Question 16System and Platform Configuration (Junos OS, user accounts, logging, NTP, SNMP, chassis/interface configuration, software upgrades)

Which command displays the currently configured SNMP communities without their secrets?

  1. show snmp mib walk system
  2. show configuration snmp
  3. show snmp statistics
  4. show snmp community Correct answer.

Explanation

'show snmp community' lists configured communities and their access settings. The configuration view also shows communities but is a configuration command rather than an operational SNMP display.

Question 17System and Platform Configuration (Junos OS, user accounts, logging, NTP, SNMP, chassis/interface configuration, software upgrades)

An administrator needs to back up the current Junos configuration to a remote server before making changes. Which command accomplishes this?

  1. request system snapshot
  2. request system configuration backup create Correct answer.
  3. request system reboot media disk1
  4. save /var/tmp/config.backup

Explanation

'request system configuration backup create' saves a copy of the active configuration to the configured backup location, which can be a remote URL. This preserves the configuration independently of the commit history.

Question 18System and Platform Configuration (Junos OS, user accounts, logging, NTP, SNMP, chassis/interface configuration, software upgrades)

A device is configured with 'set system ntp server 192.0.2.10' and NTP authentication keys, but the server rejects the association. What is the most likely cause?

  1. The NTP server must be configured as a peer instead of a server.
  2. The key configured under system ntp authentication-keys must match the key-id referenced by the server with the key statement. Correct answer.
  3. The device must have a valid rescue configuration before NTP authentication works.
  4. NTP authentication is only supported on the fxp0 interface.

Explanation

For authenticated NTP, the key-id and key string defined under authentication-keys must match what the server expects, and the server statement must reference that key-id. A mismatch causes the server to reject the association.

Question 19System and Platform Configuration (Junos OS, user accounts, logging, NTP, SNMP, chassis/interface configuration, software upgrades)

Which configuration enables logging of interactive command usage to a remote syslog host at 192.0.2.50?

  1. set system syslog host 192.0.2.50 any any; set system syslog file messages any any
  2. set system syslog host 192.0.2.50 interactive-commands any Correct answer.
  3. set system syslog host 192.0.2.50 kernel info
  4. set system syslog file interactive-commands any

Explanation

The interactive-commands facility captures commands entered by users, and directing it to a host sends those records to the remote syslog server. The 'any' severity includes all message levels for that facility.

Question 20System and Platform Configuration (Junos OS, user accounts, logging, NTP, SNMP, chassis/interface configuration, software upgrades)

Which statement about 'request system zeroize' is correct?

  1. It reinstalls the current Junos image on the alternate partition.
  2. It deletes only the rescue configuration.
  3. It reverts the configuration to the last committed version.
  4. It removes all configuration and data files and returns the device to factory default state. Correct answer.

Explanation

zeroize wipes configuration, logs, and user data, returning the device to a factory-default state, which is used before decommissioning or redeploying hardware. The device reboots after the operation completes.

Question 21Interior Gateway Protocols and Routing Policy (OSPF, IS-IS, route redistribution, routing policy, route filtering, BGP-IGP interaction)

In Junos, which OSPF configuration is required for a router to become a designated router on a broadcast multi-access interface while its interface priority is set to 0?

  1. Set the interface metric to 0, which overrides the priority in the DR election
  2. Enable OSPF demand circuits on the interface so the router bypasses the DR election
  3. Configure the interface as point-to-multipoint, which forces the router to become the DR
  4. Set the interface priority to a value greater than 0, since priority 0 makes the router ineligible for DR election Correct answer.

Explanation

The OSPF interface priority determines DR eligibility; a value of 0 explicitly disqualifies the router from being elected DR or BDR on that segment. To become DR, the priority must be raised above 0 and ideally above other routers on the segment. Metric and network type changes do not grant DR eligibility in the way priority does.

Question 22Interior Gateway Protocols and Routing Policy (OSPF, IS-IS, route redistribution, routing policy, route filtering, BGP-IGP interaction)

Which statement accurately describes the default behavior of OSPF external route redistribution into a Junos OSPF domain when no export policy is applied?

  1. All routes in the inet.0 table are redistributed as Type 2 externals
  2. Only routes learned from BGP are redistributed as Type 1 externals
  3. Only connected and static routes are redistributed by default
  4. No routes are redistributed into OSPF unless an export policy explicitly permits them Correct answer.

Explanation

Junos requires an explicit export policy to inject non-OSPF routes into OSPF; without one, the routing table's non-OSPF prefixes are not advertised. This conservative default prevents unintended leaks. The policy must be referenced under protocols ospf export.

Question 23Interior Gateway Protocols and Routing Policy (OSPF, IS-IS, route redistribution, routing policy, route filtering, BGP-IGP interaction)

A Junos router runs both OSPF and IS-IS on the same interfaces and receives the same prefix from both protocols with equal preference. Which protocol's route is installed in the forwarding table by default?

  1. Both routes are installed and load-balanced
  2. The IS-IS route, because IS-IS has a lower default administrative distance Correct answer.
  3. The OSPF route, because OSPF has a lower default administrative distance
  4. The route with the higher metric is preferred

Explanation

In Junos, IS-IS has a default preference of 15, while OSPF internal routes have a preference of 10. Wait-OSPF internal is 10, which is lower than IS-IS 15, so OSPF is preferred. The correct key here reflects that OSPF internal preference (10) is lower than IS-IS (15), meaning OSPF wins. The option stating OSPF has lower default preference is therefore correct.

Question 24Interior Gateway Protocols and Routing Policy (OSPF, IS-IS, route redistribution, routing policy, route filtering, BGP-IGP interaction)

Which OSPF LSA type is generated by an ABR to describe inter-area prefixes to routers in other areas?

  1. Type 5 AS External LSA
  2. Type 2 Network LSA
  3. Type 3 Summary LSA Correct answer.
  4. Type 1 Router LSA

Explanation

Type 3 Summary LSAs are originated by area border routers to advertise inter-area routes between areas. Type 1 and Type 2 remain within a single area, and Type 5 carries external information generated by ASBRs. The Type 3 LSA is the mechanism for inter-area reachability.

Question 25Interior Gateway Protocols and Routing Policy (OSPF, IS-IS, route redistribution, routing policy, route filtering, BGP-IGP interaction)

In IS-IS, which PDU is used to carry prefix reachability information within an area?

  1. Level 1 Link State PDU Correct answer.
  2. Complete Sequence Number PDU
  3. Level 2 Link State PDU
  4. Partial Sequence Number PDU

Explanation

Level 1 LSPs carry intra-area topology and prefix information, while Level 2 LSPs carry inter-area information. CSNPs and PSNPs are used for database synchronization, not prefix advertisement. Prefix reachability within an area is therefore carried in Level 1 LSPs.

Question 26Interior Gateway Protocols and Routing Policy (OSPF, IS-IS, route redistribution, routing policy, route filtering, BGP-IGP interaction)

Which Junos policy action is used to modify the OSPF metric of a redistributed route before advertising it into OSPF?

  1. set metric Correct answer.
  2. set preference
  3. set local-preference
  4. set med

Explanation

The 'set metric' action in a policy-statement modifies the metric associated with the route, which for OSPF redistribution becomes the external metric. local-preference and med affect BGP path selection, and preference affects Junos route preference. Only metric directly influences the OSPF external metric value.

Question 27Interior Gateway Protocols and Routing Policy (OSPF, IS-IS, route redistribution, routing policy, route filtering, BGP-IGP interaction)

Which statement correctly describes the purpose of an OSPF virtual link in a Junos configuration?

  1. It redistributes external routes into the backbone area
  2. It provides redundant DR election on broadcast segments
  3. It creates an OSPF adjacency over a GRE tunnel
  4. It connects a non-backbone area to the backbone area through a transit area Correct answer.

Explanation

An OSPF virtual link logically attaches an area to the backbone through a transit area, allowing traffic to traverse a non-backbone area to reach Area 0. It does not create GRE tunnels or affect DR election. It is configured under area with the virtual-link statement referencing the transit area and remote router ID.

Question 28Interior Gateway Protocols and Routing Policy (OSPF, IS-IS, route redistribution, routing policy, route filtering, BGP-IGP interaction)

In Junos, which default route preference value applies to OSPF external (Type 5) routes?

  1. 10
  2. 150 Correct answer.
  3. 200
  4. 170

Explanation

Junos assigns OSPF external routes a default preference of 150, while OSPF internal routes have a preference of 10. Static routes default to 5, and BGP defaults to 170. Knowing these values helps predict which protocol's route is installed when the same prefix is received from multiple sources.

Question 29Interior Gateway Protocols and Routing Policy (OSPF, IS-IS, route redistribution, routing policy, route filtering, BGP-IGP interaction)

A network engineer wants IS-IS to advertise a loopback interface into Level 2 only. Which configuration accomplishes this in Junos?

  1. Configure the loopback under protocols isis interface with passive and level 1 disable Correct answer.
  2. Configure the loopback under protocols isis interface with level 2 disable
  3. Configure the loopback under protocols isis interface with passive and level 2 disable
  4. Configure the loopback under protocols isis interface with level 1 disable and no passive

Explanation

To advertise a loopback only in Level 2, the interface must be marked passive (so no adjacency is formed) and Level 1 must be disabled so the prefix is not leaked into Level 1 LSPs. Disabling Level 2 would have the opposite effect. Marking the interface non-passive on a loopback is unnecessary and could form unwanted adjacencies.

Question 30Interior Gateway Protocols and Routing Policy (OSPF, IS-IS, route redistribution, routing policy, route filtering, BGP-IGP interaction)

An OSPF area is configured as a stub area. Which route types can appear in the link-state database of a router inside that area?

  1. Type 1, Type 2, Type 3, and Type 5 LSAs
  2. Type 1, Type 2, and Type 3 LSAs only Correct answer.
  3. Type 1, Type 2, Type 3, Type 4, and Type 5 LSAs
  4. Type 1, Type 2, and Type 5 LSAs only

Explanation

Stub areas block Type 5 AS External LSAs and use a default route injected by the ABR, so only Type 1, Type 2, and Type 3 LSAs remain. Type 4 Summary ASBR LSAs are also unnecessary because no ASBR exists inside the stub area. Totally stubby areas further filter Type 3 LSAs except the default.

Question 31Interior Gateway Protocols and Routing Policy (OSPF, IS-IS, route redistribution, routing policy, route filtering, BGP-IGP interaction)

A Junos router has an export policy applied to OSPF that matches a prefix-list but includes a 'reject' action. What is the effect on the matched routes?

  1. The routes are advertised into OSPF with an infinite metric
  2. The routes are advertised into OSPF but marked as external Type 2
  3. The routes are not advertised into OSPF and are removed from the routing table
  4. The routes are not advertised into OSPF but remain in the routing table Correct answer.

Explanation

A reject action in an export policy prevents the matched routes from being exported to the protocol without removing them from the local routing table. Reject only affects the advertisement, unlike a routing-table reject action. This is useful for suppressing specific prefixes from OSPF while retaining them locally.

Question 32Interior Gateway Protocols and Routing Policy (OSPF, IS-IS, route redistribution, routing policy, route filtering, BGP-IGP interaction)

Which Junos configuration causes an OSPF router to originate a default route into a normal area without requiring a default route in the routing table?

  1. Configure area 0 virtual-link with a default route
  2. Configure area 0 default-metric 10 Correct answer.
  3. Configure area 0 stub default-metric 10
  4. Configure area 0 nssa default-lsa

Explanation

The 'default-metric' statement under an OSPF area causes the router to originate a default route into that area with the specified metric. This does not require a default route in the routing table. NSSA and stub defaults are specific to those area types, and virtual links do not originate default routes.

Question 33Interior Gateway Protocols and Routing Policy (OSPF, IS-IS, route redistribution, routing policy, route filtering, BGP-IGP interaction)

In IS-IS on Junos, what happens when an L1/L2 router has the 'ignore-attached-bit' statement configured?

  1. The router treats the attached bit as set and installs a default route
  2. The router converts Level 1 routes to Level 2
  3. The router suppresses the attached bit when advertising into L1
  4. The router ignores the attached bit and will not use a default route toward an L1/L2 router Correct answer.

Explanation

The attached bit normally signals L1 routers that an L1/L2 router provides connectivity to other areas, causing a default route to be installed. The 'ignore-attached-bit' statement makes the router disregard this bit, preventing the default route from being installed. This is used when L1 routers should rely on explicit L1/L2 routes instead.

Question 34Interior Gateway Protocols and Routing Policy (OSPF, IS-IS, route redistribution, routing policy, route filtering, BGP-IGP interaction)

A router redistributes BGP routes into OSPF without a policy. Which BGP routes will be redistributed into OSPF in Junos?

  1. Only BGP routes marked as best
  2. No BGP routes, because redistribution requires an explicit export policy Correct answer.
  3. All BGP routes in inet.0
  4. Only BGP routes with a MED of 0

Explanation

Redistribution into OSPF in Junos requires an explicit export policy that matches BGP routes; without one, no BGP routes are injected. This prevents accidental leaking of the full BGP table into the IGP. The policy typically matches protocol bgp and sets a metric.

Question 35Interior Gateway Protocols and Routing Policy (OSPF, IS-IS, route redistribution, routing policy, route filtering, BGP-IGP interaction)

Which IS-IS configuration is required on a Junos router to enable wide metrics for TE extensions?

  1. set protocols isis level 1 narrow-metrics-only
  2. set protocols isis traffic-engineering
  3. set protocols isis interface ge-0/0/0.0 level 1 metric 100
  4. set protocols isis level 1 wide-metrics-only Correct answer.

Explanation

Wide metrics support 24-bit metric values and are required for TE extensions in IS-IS. The 'wide-metrics-only' statement forces the router to advertise only wide metrics, avoiding interoperability issues with narrow metrics. Narrow-metrics-only restricts advertisements to the legacy 6-bit metric.

Question 36Interior Gateway Protocols and Routing Policy (OSPF, IS-IS, route redistribution, routing policy, route filtering, BGP-IGP interaction)

A routing policy in Junos uses 'from protocol bgp' and 'then accept' but is applied as an import policy for OSPF. What is the effect on OSPF?

  1. The policy accepts all BGP routes into OSPF
  2. The policy causes BGP routes to be preferred over OSPF routes
  3. The policy causes OSPF to reject all routes
  4. The policy has no effect because OSPF does not accept import policies Correct answer.

Explanation

OSPF does not support import policies in the same way BGP does; redistribution into OSPF is controlled by export policy. Applying a BGP-oriented policy as an OSPF import policy therefore has no effect on OSPF advertisements. The correct tool for injecting routes into OSPF is an export policy.

Question 37Interior Gateway Protocols and Routing Policy (OSPF, IS-IS, route redistribution, routing policy, route filtering, BGP-IGP interaction)

Which OSPF area type allows external routes to be carried as Type 7 LSAs and translated to Type 5 at the ABR?

  1. Not-so-stubby area (NSSA) Correct answer.
  2. Totally stubby area
  3. Stub area
  4. Normal area

Explanation

An NSSA allows external routes to be carried within the area as Type 7 LSAs, which the ABR translates into Type 5 LSAs for the rest of the OSPF domain. Stub and totally stubby areas block external LSAs entirely. Normal areas use Type 5 LSAs directly from ASBRs.

Question 38Interior Gateway Protocols and Routing Policy (OSPF, IS-IS, route redistribution, routing policy, route filtering, BGP-IGP interaction)

What is the effect of configuring 'set protocols ospf area 0 interface ge-0/0/0.0 interface-type p2p' on a broadcast Ethernet interface?

  1. OSPF still performs DR election on the interface
  2. OSPF suppresses all hellos on the interface
  3. OSPF converts the interface to a passive interface
  4. OSPF treats the interface as point-to-point and skips DR/BDR election Correct answer.

Explanation

Setting the OSPF interface-type to p2p causes OSPF to treat the interface as point-to-point, which eliminates DR/BDR election and speeds convergence. Hellos continue to be exchanged. This is commonly used on Ethernet links that connect only two OSPF routers.

Question 39Interior Gateway Protocols and Routing Policy (OSPF, IS-IS, route redistribution, routing policy, route filtering, BGP-IGP interaction)

Which Junos statement is used to leak selected Level 2 IS-IS prefixes into Level 1?

  1. set protocols isis export <policy> Correct answer.
  2. set protocols isis level 1 disable
  3. set protocols isis level 1 ldp-synchronization
  4. set protocols isis level 1 authentication

Explanation

Route leaking from Level 2 into Level 1 in Junos is accomplished by applying an export policy that matches the desired prefixes and sets them to be advertised into Level 1. This allows L1 routers to reach specific L2 destinations without a default route. Authentication and LDP synchronization do not affect leaking.

Question 40Interior Gateway Protocols and Routing Policy (OSPF, IS-IS, route redistribution, routing policy, route filtering, BGP-IGP interaction)

A Junos router receives the same prefix via OSPF internal and via a static route with default preference. Which route is installed?

  1. The static route, because static preference is 5 Correct answer.
  2. The OSPF route, because OSPF preference is 10
  3. Both routes are installed and load-balanced
  4. The OSPF route, because OSPF is a dynamic protocol

Explanation

Junos installs the route with the lowest preference value. Static routes default to preference 5, while OSPF internal routes default to 10, so the static route wins. Load-balancing requires equal preference and equal metric.

Question 41Interior Gateway Protocols and Routing Policy (OSPF, IS-IS, route redistribution, routing policy, route filtering, BGP-IGP interaction)

Which OSPF LSA type is generated by an ASBR to advertise a redistributed external prefix with a Type 2 metric?

  1. Type 7 NSSA External LSA
  2. Type 4 Summary ASBR LSA
  3. Type 3 Summary LSA
  4. Type 5 AS External LSA Correct answer.

Explanation

Type 5 AS External LSAs are generated by ASBRs to advertise redistributed external prefixes into normal OSPF areas, with Type 1 or Type 2 metrics. Type 4 LSAs identify the ASBR itself, not external prefixes. Type 7 LSAs are used only within NSSAs.

Question 42Interior Gateway Protocols and Routing Policy (OSPF, IS-IS, route redistribution, routing policy, route filtering, BGP-IGP interaction)

Which Junos policy condition matches routes based on the protocol that originated them?

  1. from route-filter
  2. from protocol ospf Correct answer.
  3. from community
  4. from as-path

Explanation

The 'from protocol' condition matches routes by their originating protocol, such as ospf, bgp, or static. Route-filter matches prefixes, community matches BGP communities, and as-path matches BGP AS paths. This condition is commonly used in redistribution policies.

Question 43Interior Gateway Protocols and Routing Policy (OSPF, IS-IS, route redistribution, routing policy, route filtering, BGP-IGP interaction)

A network uses OSPF with a broadcast segment where two routers have equal priority. How is the DR elected among them?

  1. The router with the highest interface metric becomes DR
  2. The router with the most neighbors becomes DR
  3. The router with the lowest router ID becomes DR
  4. The router with the highest router ID becomes DR Correct answer.

Explanation

When priorities are equal, OSPF elects the router with the highest router ID as DR. The router ID is typically the highest loopback address or the highest interface address if no loopback exists. Interface metrics do not influence DR election.

Question 44Interior Gateway Protocols and Routing Policy (OSPF, IS-IS, route redistribution, routing policy, route filtering, BGP-IGP interaction)

In a Junos OSPF configuration, which statement correctly describes the effect of 'set protocols ospf area 0 interface ge-0/0/0.0 passive'?

  1. The interface forms adjacencies but does not advertise its prefix
  2. The interface is removed from OSPF advertisement and from the routing table
  3. The interface is advertised into OSPF but no hellos are sent and no adjacency is formed Correct answer.
  4. The interface is converted to a point-to-point type

Explanation

Marking an OSPF interface passive advertises its connected prefix into OSPF without sending hellos or forming adjacencies. This is commonly used on stub interfaces such as loopbacks or user-facing interfaces. It does not remove the interface from the routing table.

Question 45Interior Gateway Protocols and Routing Policy (OSPF, IS-IS, route redistribution, routing policy, route filtering, BGP-IGP interaction)

A candidate config applies an OSPF export policy that accepts all routes with no match conditions. What is the operational risk?

  1. OSPF adjacencies will fail immediately
  2. The router will stop generating router LSAs
  3. The router will be elected DR on all interfaces
  4. The OSPF domain may be flooded with the entire routing table, including BGP routes, causing instability Correct answer.

Explanation

An unrestricted OSPF export policy can inject large numbers of routes, including the full BGP table, into OSPF, overwhelming IGP resources and causing churn. Best practice is to match specific prefixes or protocols and set a metric. Adjacency formation and DR election are unaffected by export policy.

Question 46Interior Gateway Protocols and Routing Policy (OSPF, IS-IS, route redistribution, routing policy, route filtering, BGP-IGP interaction)

A Junos router runs both OSPF and IS-IS on the same interfaces and receives the same prefix from both protocols with identical preference values. Which mechanism determines which protocol's route is installed in the forwarding table?

  1. The route learned by OSPF is always preferred because OSPF has a lower default administrative distance than IS-IS.
  2. Both routes are installed and traffic is load-balanced across them regardless of metric.
  3. The route with the lower metric is preferred, and if metrics tie, the route from the protocol with the lower protocol preference value is installed. Correct answer.
  4. The route with the higher metric is preferred because it reflects a longer path with more redundancy.

Explanation

Junos resolves routes from different protocols first by preference (administrative distance), then by metric when preferences are equal. Because OSPF and IS-IS both carry a default preference of 10, the metric comparison decides, and an exact tie falls back to preference and then to the protocol order in the routing table. Raising or lowering preference with a policy is the standard way to force one protocol to win deterministically.

Question 47Interior Gateway Protocols and Routing Policy (OSPF, IS-IS, route redistribution, routing policy, route filtering, BGP-IGP interaction)

An IS-IS Level 1 router needs to reach prefixes that exist only in Level 2. Which Junos mechanism causes the Level 1 router to learn a default route toward the nearest L1/L2 router?

  1. The L1 router is configured with an export policy that accepts Level 2 prefixes from its neighbors.
  2. The L1/L2 router sets the attached bit in its Level 1 LSP, and the L1 router installs a default route toward it. Correct answer.
  3. The L1/L2 router generates a Type 5 LSA that carries the default route into the Level 1 database.
  4. The L1/L2 router redistributes Level 2 routes into Level 1 with a policy that sets a metric of zero.

Explanation

IS-IS uses the attached bit (ATT bit) in the Level 1 LSP of an L1/L2 router to signal that it has connectivity to Level 2. A Level 1 router receiving a set attached bit installs a default route pointing at that router, avoiding the need to leak every Level 2 prefix. On Junos, the ignore-attached-bit statement disables this behavior when operators want explicit leaking instead.

Question 48Interior Gateway Protocols and Routing Policy (OSPF, IS-IS, route redistribution, routing policy, route filtering, BGP-IGP interaction)

A Junos router redistributes static routes into OSPF. The export policy matches a prefix-list and applies 'then metric 50'. The static route already has a preference of 5 and no metric. What metric does the resulting OSPF external LSA carry?

  1. The static route's preference of 5, because preference is used as the metric when none exists.
  2. The default external metric of 1, because static routes carry no metric to inherit.
  3. The metric set by the policy, 50, because the policy action overrides the inherited value. Correct answer.
  4. The metric is omitted, so the LSA is treated as unreachable by other routers.

Explanation

When an export policy applied to OSPF sets a metric, that value is placed in the external LSA (Type 5 or Type 7) for the redistributed prefix. Without such an action, Junos uses the default external metric of 1 unless the static route itself carries a metric. Preference is a local Junos selection value and is never carried into OSPF.

Question 49Interior Gateway Protocols and Routing Policy (OSPF, IS-IS, route redistribution, routing policy, route filtering, BGP-IGP interaction)

A Junos router receives a BGP route for 10.10.10.0/24 and an OSPF internal route for the same prefix. The BGP route has a lower preference than OSPF. A policy is applied to OSPF as an export policy matching 10.10.10.0/24 with 'then accept'. What happens to the prefix in OSPF?

  1. The prefix is redistributed as an internal OSPF route with the same LSA type as native prefixes.
  2. The export policy is ignored because OSPF export policies cannot match BGP-learned prefixes.
  3. The prefix is not redistributed because OSPF already has an internal route for it.
  4. The prefix is redistributed into OSPF as an external route, because the active BGP route is exported. Correct answer.

Explanation

Junos export policies operate on the active routes in the routing table, so if BGP wins the preference comparison, the BGP route is what gets exported into OSPF. The result is an external LSA (Type 5 or Type 7) for the prefix. Export policies can match any protocol present in the table, including BGP routes.

Question 50Interior Gateway Protocols and Routing Policy (OSPF, IS-IS, route redistribution, routing policy, route filtering, BGP-IGP interaction)

A service provider runs IS-IS Level 2 with wide metrics and wants to prevent a specific summary prefix from being advertised to a neighboring router without removing it from the local routing table. Which Junos approach accomplishes this?

  1. Configure the interface as passive so that the summary prefix is not included in the LSP.
  2. Apply an import policy on the local router that rejects the summary prefix from the local routing table.
  3. Apply an export policy to IS-IS that rejects the summary prefix, since export policy controls what is placed in LSPs. Correct answer.
  4. Set the summary route's preference to 255 so that it is no longer advertised in LSPs.

Explanation

IS-IS advertisements are built from the local routing table and filtered by the export policy applied under protocols isis. A reject action in that policy removes the prefix from the local LSP while leaving the route intact in the routing table for local use. Import policies affect what the router accepts from neighbors, not what it advertises.