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JNCIP-SP practice questions

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Question 1Service Provider Routing and Switching

In Junos, which routing table holds the routes that the forwarding table is populated from for IPv4 unicast traffic after route preference selection?

  1. inet.0 Correct answer.
  2. inet.3
  3. inet6.0
  4. mpls.0

Explanation

inet.0 is the primary IPv4 unicast routing table where the best routes selected by preference are installed and from which the forwarding table (kernel) is built. Other tables such as inet.3 hold resolution routes for BGP next hops and inet6.0 handles IPv6.

Question 2Service Provider Routing and Switching

A service provider wants to verify which next hop a BGP route in inet.0 will resolve to before it is installed. Which command shows the route resolution details for a specific destination in Junos?

  1. show route forwarding-table destination 203.0.113.0/24
  2. show route table inet.3
  3. show route 203.0.113.0/24 detail Correct answer.
  4. show bgp neighbor

Explanation

The 'show route <prefix> detail' command displays the selected route along with its resolved next-hop information, including the indirect next hop and the resolved forwarding next hop. This lets an engineer confirm resolution before troubleshooting forwarding.

Question 3Service Provider Routing and Switching

Which BGP attribute is used by Junos as the tiebreaker after Local Preference and before Origin when selecting the best path?

  1. Router ID
  2. Cluster list length
  3. MED
  4. AS Path length Correct answer.

Explanation

Junos best-path selection order places higher Local Preference first, then shorter AS Path length, then lower Origin, then lower MED. AS Path length therefore precedes Origin and MED in the decision process.

Question 4Service Provider Routing and Switching

An engineer configures 'set protocols bgp group EBGP type external' and 'set protocols bgp group EBGP peer-as 65001' but the session stays in Active state. Which is the most likely cause?

  1. The local router has no export policy configured
  2. The BGP router ID is not set
  3. The remote peer is unreachable or not listening on TCP port 179 Correct answer.
  4. The group is missing a multihop configuration

Explanation

An Active state indicates the local router is trying to establish the TCP session but cannot complete the three-way handshake, typically because the peer is unreachable or not accepting connections on port 179. Missing export policy or router ID would not prevent the TCP session from forming.

Question 5Service Provider Routing and Switching

Which statement accurately describes the default behavior of a Junos export policy on a BGP session with no policy explicitly configured?

  1. Only directly connected routes are advertised
  2. No routes are advertised because the default export policy rejects everything Correct answer.
  3. Only routes learned from the same AS are advertised
  4. All routes are advertised by default

Explanation

Junos applies an implicit deny-all export policy when no export policy is configured, so no routes are advertised to the BGP peer. An explicit policy accepting routes must be applied for advertisements to occur.

Question 6Service Provider Routing and Switching

Which Junos configuration element determines the preference value assigned to routes learned via OSPF internal versus external?

  1. The reference-bandwidth under protocols ospf
  2. The external-preference under protocols ospf
  3. The preference statement under protocols ospf Correct answer.
  4. The metric-type under the export policy

Explanation

The 'preference' statement under [edit protocols ospf] sets the route preference for OSPF routes, and external-preference separately sets the value for external routes. Route preference influences which protocol's route is installed in inet.0.

Question 7Service Provider Routing and Switching

A provider uses IS-IS level 2 only in its core. Which statement describes the default behavior of an IS-IS level 1-2 router regarding leaking?

  1. Level 1 routes are automatically leaked into level 2
  2. Level 2 routes are automatically leaked into level 1
  3. Leaking is enabled by default only when wide metrics are used
  4. Level 1 routes are not leaked into level 2 by default in Junos Correct answer.

Explanation

Junos does not leak level 1 routes into level 2 by default; leaking must be explicitly configured with an export policy or the 'level 1 disable' combined with policy. Understanding this prevents unintended transit through level 1 areas.

Question 8Service Provider Routing and Switching

Which MPLS signaling protocol is used by default in Junos when LDP is enabled on an interface?

  1. LDP Correct answer.
  2. Static label-switched paths
  3. BGP labeled unicast
  4. RSVP

Explanation

Enabling LDP under [edit protocols ldp] with interfaces configured causes Junos to signal label bindings using LDP by default. RSVP and BGP labeled unicast must be configured separately.

Question 9Service Provider Routing and Switching

An engineer wants to verify that LDP label bindings have been received from a peer. Which command best shows the label bindings learned from a specific neighbor?

  1. show ldp database Correct answer.
  2. show ldp neighbor
  3. show mpls lsp
  4. show route table mpls.0

Explanation

The 'show ldp database' command displays the label bindings exchanged with LDP neighbors, showing both input and output label mappings. This confirms whether label distribution is working correctly.

Question 10Service Provider Routing and Switching

Which RSVP configuration parameter must match on both ends of a traffic-engineering LSP for the session to establish?

  1. The metric value only
  2. The bandwidth reservation only
  3. The admin-group color only
  4. The LSP name and the tunnel endpoints Correct answer.

Explanation

RSVP-TE LSPs are identified by the tunnel endpoint and the LSP name (extended tunnel ID) which must be consistent for the session to form. Bandwidth, admin groups, and metrics influence path selection but do not define the session identity.

Question 11Service Provider Routing and Switching

Which statement describes the role of the route reflector cluster ID in BGP?

  1. It determines the local preference of reflected routes
  2. It sets the MED value for reflected routes
  3. It replaces the router ID for the reflector
  4. It prevents routing loops by identifying the cluster and is carried in the cluster list Correct answer.

Explanation

The cluster ID identifies a route reflector cluster and is added to the cluster list attribute when routes are reflected, allowing other reflectors to detect loops. It is independent of router ID and does not affect local preference or MED.

Question 12Service Provider Routing and Switching

A provider wants to prevent a customer's routes from being advertised to another customer. Which BGP mechanism provides the most direct control in Junos?

  1. An export policy applied to the relevant BGP group Correct answer.
  2. A larger AS path prepend
  3. A higher MED on the customer routes
  4. A lower local preference on the customer routes

Explanation

An export policy applied to the BGP group controls exactly which routes are advertised to that peer, providing direct and deterministic filtering. MED, local preference, and AS path prepending influence path selection but do not prevent advertisement.

Question 13Service Provider Routing and Switching

Which Junos command displays the BGP routes received from a specific neighbor before policy is applied?

  1. show bgp summary
  2. show route receive-protocol bgp <neighbor> Correct answer.
  3. show route protocol bgp
  4. show route advertising-protocol bgp <neighbor>

Explanation

The 'show route receive-protocol bgp <neighbor>' command shows routes received from that neighbor prior to import policy evaluation, which is valuable for verifying what the peer is sending. The advertising-protocol variant shows what is being sent instead.

Question 14Service Provider Routing and Switching

Which statement describes the default behavior of OSPF on a Junos interface that has no explicit OSPF configuration but is included in an OSPF area?

  1. The interface participates in OSPF with a default metric of 1 Correct answer.
  2. The interface uses the bandwidth-based metric automatically
  3. The interface uses a metric of 10 by default
  4. The interface is excluded from OSPF until a metric is set

Explanation

Junos assigns a default OSPF metric of 1 to interfaces included in an OSPF area unless a metric is explicitly configured. Bandwidth-based metrics require reference-bandwidth configuration.

Question 15Service Provider Routing and Switching

An engineer needs to summarize OSPF inter-area routes from area 1 into area 0. Which configuration accomplishes this on the ABR?

  1. area 1 nssa with a range statement
  2. area 1 range <prefix> Correct answer.
  3. area 0 range <prefix>
  4. export policy with a summary route

Explanation

On an ABR, the 'area <area-id> range <prefix>' statement summarizes routes from that area into the backbone. To summarize area 1 routes into area 0, the range is configured under area 1.

Question 16Service Provider Routing and Switching

Which statement is true about the Junos forwarding table versus the routing table?

  1. The forwarding table contains only the active next hops used by the kernel for packet forwarding Correct answer.
  2. The routing table is used directly for packet forwarding
  3. The forwarding table is rebuilt only when the router reboots
  4. The forwarding table contains all routes including inactive ones

Explanation

The forwarding table (kernel) contains the active forwarding next hops derived from the best routes in the routing table. Inactive routes remain only in the routing table, and the forwarding table is updated dynamically as routes change.

Question 17Service Provider Routing and Switching

Which BGP feature allows a provider to receive only a default route from a customer while still applying policy to that default?

  1. A route reflector configuration
  2. A receive policy that accepts only 0.0.0.0/0 Correct answer.
  3. A default-originate statement on the customer session
  4. An export policy that prepends the AS path

Explanation

A receive (import) policy that accepts only the default route filters incoming advertisements so only 0.0.0.0/0 is retained. Default-originate is used to send a default to a peer, not to filter received routes.

Question 18Service Provider Routing and Switching

Which command verifies the MPLS label stack imposed on packets for a specific RSVP LSP in Junos?

  1. show ldp database
  2. show interfaces ge-0/0/0 extensive
  3. show route table inet.0
  4. show mpls lsp detail Correct answer.

Explanation

The 'show mpls lsp detail' command displays LSP state including the outgoing label and next hop, confirming the label stack imposed for the tunnel. This helps verify that the LSP is up and forwarding correctly.

Question 19Service Provider Routing and Switching

Which statement describes the purpose of the BGP 'local-preference' attribute in a service provider network?

  1. It sets the MPLS label for the route
  2. It influences outbound path selection within the local AS Correct answer.
  3. It controls the TCP port used for the session
  4. It influences inbound path selection at the remote AS

Explanation

Local preference is a well-known discretionary attribute used within an AS to influence which exit point is chosen for outbound traffic. It is not advertised to external peers, so it does not affect inbound path selection at remote ASes.

Question 20Service Provider Routing and Switching

A provider wants to ensure that a specific prefix is preferred over an equal-length prefix learned from another peer. Which attribute should be manipulated first in Junos best-path selection?

  1. Router ID
  2. Origin
  3. MED
  4. Local preference Correct answer.

Explanation

Local preference is the earliest tiebreaker among the attributes listed, so setting a higher local preference on the desired route ensures it is selected before MED, Origin, or Router ID are considered. This provides deterministic control within the local AS.

Question 21Service Provider Routing and Switching

Which statement describes the default Junos behavior for an interface configured with 'family inet' but no explicit OSPF hello interval?

  1. The default hello interval is 5 seconds
  2. The default hello interval is 30 seconds
  3. The default hello interval is 1 second
  4. The default hello interval is 10 seconds Correct answer.

Explanation

Junos uses a default OSPF hello interval of 10 seconds on broadcast and point-to-point interfaces, with a dead interval of 40 seconds. These defaults can be modified per interface if needed.

Question 22Service Provider Routing and Switching

Which Junos feature allows a router to advertise a summary route for a set of BGP prefixes while suppressing the more specific advertisements?

  1. A default-originate statement
  2. Aggregate routes with the summary-only option Correct answer.
  3. Static routes with no-readvertise
  4. An AS path prepend policy

Explanation

The 'aggregate' statement with 'summary-only' creates an aggregate route and suppresses the contributing more-specific routes from advertisement. This reduces the size of the BGP table advertised to peers.

Question 23Service Provider Routing and Switching

A provider uses BGP labeled unicast to distribute labels for prefixes. Which statement describes how this differs from LDP?

  1. Labels are distributed via BGP rather than a separate LDP session Correct answer.
  2. Labels are distributed only within a single OSPF area
  3. Labels are assigned per interface rather than per prefix
  4. Labels are distributed only for directly connected prefixes

Explanation

BGP labeled unicast carries label bindings inside BGP updates for the labeled-unicast address family, eliminating the need for a separate LDP session. It is commonly used for seamless MPLS and inter-AS label distribution.

Question 24Service Provider Routing and Switching

Which statement describes the effect of the Junos 'multipath' statement under a BGP group when multiple equal-cost paths exist?

  1. It allows multiple BGP paths to be installed in the forwarding table for load balancing Correct answer.
  2. It selects only the oldest path
  3. It forces all paths to use the same next hop
  4. It disables best-path selection

Explanation

The 'multipath' statement permits multiple equal-cost BGP paths to be installed in the forwarding table, enabling load balancing across them. Without it, only a single best path is used for forwarding.

Question 25Service Provider Routing and Switching

Which statement best describes the role of the Junos 'route-preference' value when two protocols advertise the same prefix?

  1. The route with the higher preference value is preferred
  2. Preference applies only to BGP routes
  3. Preference is ignored when prefixes match
  4. The route with the lower preference value is preferred Correct answer.

Explanation

In Junos, a lower route preference value indicates a more preferred route, so when two protocols advertise the same prefix the one with the lower preference is installed in the routing table. This is why OSPF internal (10) beats EBGP (170) by default.

Question 26Service Provider Routing and Switching

Which Junos configuration statement enables the device to act as a route reflector for a BGP group?

  1. cluster 10.0.0.1; Correct answer.
  2. route-reflector 10.0.0.1;
  3. reflector-id 10.0.0.1;
  4. bgp-reflector 10.0.0.1;

Explanation

In Junos, route reflection is enabled by configuring a cluster identifier under the BGP group or global BGP hierarchy using the cluster statement. The cluster ID is used in the CLUSTER_LIST attribute to prevent routing loops. The other statements do not exist in Junos BGP configuration.

Question 27Service Provider Routing and Switching

Which Junos command displays the contents of the forwarding table for a specific prefix?

  1. show route forwarding-table destination 192.0.2.0/24 Correct answer.
  2. show route protocol bgp
  3. show route table inet.0 192.0.2.0/24
  4. show route summary

Explanation

The show route forwarding-table command displays the entries installed in the kernel forwarding table, which is used for packet forwarding. The destination option filters the output to a specific prefix. The show route command displays the routing table (RIB), not the forwarding table.

Question 28Service Provider Routing and Switching

What is the default preference value for OSPF internal routes in Junos?

  1. 100
  2. 10 Correct answer.
  3. 150
  4. 170

Explanation

Junos assigns a default preference of 10 to OSPF internal routes, making them preferred over many other protocols. OSPF external routes have a default preference of 150, and RIP has 100. Static routes have a default preference of 5.

Question 29Service Provider Routing and Switching

Which statement about the Junos 'export' policy in BGP is correct?

  1. It filters routes advertised to BGP neighbors. Correct answer.
  2. It sets the MED attribute on received routes.
  3. It filters routes received from BGP neighbors.
  4. It modifies the local preference of received routes.

Explanation

In Junos, an export policy applied to BGP controls which routes are advertised to neighbors and can modify attributes of those advertised routes. Import policy controls routes received from neighbors. Local preference and MED for received routes are typically set via import policy.

Question 30Service Provider Routing and Switching

Which Junos configuration statement is required to enable MPLS on an interface?

  1. mpls enable
  2. protocol mpls
  3. family mpls Correct answer.
  4. mpls-interface

Explanation

To enable MPLS on a Junos interface, you must configure the family mpls statement under the interface unit. This allows MPLS labels to be processed on that interface. The other statements are not valid Junos configuration for enabling MPLS.

Question 31Service Provider Routing and Switching

Which command displays the IS-IS adjacencies and their states on a Junos router?

  1. show isis database
  2. show isis routes
  3. show isis interface
  4. show isis adjacency Correct answer.

Explanation

The show isis adjacency command lists IS-IS neighbors, their states, and the interfaces they are reachable through. The show isis interface command displays IS-IS interface parameters, show isis database shows the link-state database, and show isis routes shows the IS-IS routing table.

Question 32Service Provider Routing and Switching

Which Junos feature allows a router to assign different preferences to routes from the same protocol based on a match condition?

  1. Metric manipulation
  2. Administrative distance
  3. Route preference hierarchy
  4. Policy with preference action Correct answer.

Explanation

In Junos, routing policy can set the preference of routes that match a policy term using the preference action. This allows granular control over route selection within a protocol. The other options are either not Junos features or do not provide per-route preference changes.

Question 33Service Provider Routing and Switching

Which statement describes the purpose of the BGP 'as-path' attribute in a service provider network?

  1. It identifies the originator of a route within the AS.
  2. It records the sequence of autonomous systems a route has traversed. Correct answer.
  3. It indicates the local preference for a route within the AS.
  4. It specifies the next-hop IP address for a route.

Explanation

The AS path attribute is a list of AS numbers that a route has passed through, used for loop prevention and path selection. Local preference is a separate attribute used within an AS. Next-hop is another attribute, and originator ID is used in route reflection.

Question 34Service Provider Routing and Switching

An engineer wants to verify that a specific RSVP LSP is up and operational. Which command should be used?

  1. show rsvp session
  2. show mpls lsp name <lsp-name> Correct answer.
  3. show mpls interface
  4. show route protocol rsvp

Explanation

The show mpls lsp name command displays detailed information about a specific LSP, including its state (Up or Down). The show rsvp session command shows RSVP sessions, which are related but do not directly show LSP operational status. The other commands do not provide LSP status.

Question 35Service Provider Routing and Switching

Which Junos configuration enables traffic engineering extensions for OSPF?

  1. mpls-te
  2. traffic-engineering Correct answer.
  3. ospf-te
  4. te-extensions

Explanation

In Junos, traffic engineering extensions for OSPF are enabled with the traffic-engineering statement under the OSPF protocol configuration. This allows OSPF to advertise TE link parameters. The other statements are not valid Junos configuration for this purpose.

Question 36Service Provider Routing and Switching

Which statement about the BGP 'next-hop-self' configuration in Junos is correct?

  1. It changes the next hop of received routes to the local address.
  2. It sets the next-hop attribute to the peer address for all routes.
  3. It causes the router to advertise itself as the next hop for routes sent to a neighbor. Correct answer.
  4. It enables the router to accept routes with a next hop of 0.0.0.0.

Explanation

The next-hop-self statement in Junos BGP configuration causes the router to set the next-hop attribute to its own address when advertising routes to a specified neighbor. This is commonly used in iBGP to ensure reachability. It does not affect received routes or set the next hop to the peer address.

Question 37Service Provider Routing and Switching

A service provider uses MPLS LDP for label distribution. Which command shows the label bindings received from a specific LDP neighbor?

  1. show ldp database neighbor <neighbor-address> Correct answer.
  2. show route protocol ldp
  3. show ldp interface
  4. show ldp session neighbor <neighbor-address>

Explanation

The show ldp database neighbor command displays the label bindings received from a specific LDP neighbor, including the incoming label and prefix. The show ldp session command shows session state, not bindings. The other commands do not provide label binding details.

Question 38Service Provider Routing and Switching

Which Junos configuration is required to enable BGP route reflection within a cluster?

  1. cluster <cluster-id>; Correct answer.
  2. reflector <cluster-id>;
  3. route-reflector <cluster-id>;
  4. bgp-cluster <cluster-id>;

Explanation

To enable route reflection, you configure the cluster statement with a cluster ID under the BGP group or global BGP hierarchy. The cluster ID is used in the CLUSTER_LIST attribute to prevent loops. The other statements are not valid Junos syntax.

Question 39Service Provider Routing and Switching

An engineer wants to filter OSPF routes from being installed in the routing table. Which Junos feature should be used?

  1. A route filter applied under the OSPF area
  2. A policy applied with the export statement under OSPF
  3. A policy applied with the import statement under OSPF Correct answer.
  4. A firewall filter applied to the OSPF interface

Explanation

In Junos, an import policy under OSPF controls which OSPF routes are installed in the routing table. An export policy controls which routes are advertised into OSPF. Firewall filters and route filters do not directly filter OSPF routes from the routing table.

Question 40Service Provider Routing and Switching

Which statement describes the default behavior of Junos when a BGP neighbor is configured with multiple address families?

  1. Only IPv4 unicast is enabled by default.
  2. The neighbor must be configured separately for each family. Correct answer.
  3. The neighbor session will not establish until families are configured.
  4. All families are enabled by default.

Explanation

In Junos, each address family for a BGP neighbor must be explicitly configured under the neighbor or group hierarchy. For example, family inet unicast and family inet-vpn unicast must be configured separately. By default, no families are enabled unless specified.

Question 41Service Provider Routing and Switching

A network operator wants to prevent a specific prefix from being advertised to an external BGP peer. Which Junos policy action accomplishes this?

  1. accept
  2. reject Correct answer.
  3. discard
  4. next term

Explanation

In a Junos export policy, the reject action causes matching routes to be neither advertised nor installed, effectively preventing the prefix from being sent to the peer. The accept action allows the route, and next term continues evaluation. The discard action is used for other purposes.

Question 42Service Provider Routing and Switching

Which command displays the MPLS label operations for a specific prefix in the forwarding table?

  1. show route table mpls.0
  2. show route protocol ldp
  3. show route forwarding-table destination <prefix> detail Correct answer.
  4. show mpls lsp

Explanation

The show route forwarding-table destination command with the detail option displays the forwarding entries for a prefix, including MPLS label operations such as push, swap, or pop. The other commands show MPLS label space or LSPs but not the forwarding operations for a specific prefix.

Question 43Service Provider Routing and Switching

Which statement about the BGP 'local-preference' attribute is correct?

  1. It is used to select the best path among routes learned from eBGP peers.
  2. It is only used for route reflection.
  3. It is a transitive attribute that is propagated to external peers.
  4. It is used to select the best path among routes learned from iBGP peers. Correct answer.

Explanation

Local preference is a well-known discretionary attribute used within an autonomous system to prefer one path over another. It is not propagated to external BGP peers. It is used for all iBGP-learned routes, not just for route reflection.

Question 44Service Provider Routing and Switching

An engineer wants to summarize OSPF routes from area 1 into area 0. Which configuration accomplishes this on an ABR?

  1. area 1 stub;
  2. area 0 range 10.0.0.0/16;
  3. area 1 range 10.0.0.0/16; Correct answer.
  4. area 1 nssa;

Explanation

To summarize inter-area routes from area 1 into the backbone, you configure an area range under the source area (area 1) on the ABR. The area 0 range command would summarize routes from area 0 into other areas. The stub and NSSA options do not perform summarization.

Question 45Service Provider Routing and Switching

Which Junos feature allows a router to advertise a summary route for a set of BGP prefixes while suppressing the more specific routes?

  1. suppress
  2. generate
  3. summary-only
  4. aggregate Correct answer.

Explanation

In Junos, the aggregate statement under BGP allows you to create an aggregate route and optionally suppress the more specific routes using the summary-only option. The generate statement creates a route but does not suppress specifics. The suppress and summary-only options are used within aggregate configuration.

Question 46Service Provider Routing and Switching

Which statement describes the effect of the Junos 'multipath' statement under a BGP group?

  1. It allows multiple equal-cost paths to be installed in the forwarding table. Correct answer.
  2. It enables load balancing across multiple BGP sessions.
  3. It allows BGP to select multiple best paths for advertisement.
  4. It enables multipath for all protocols.

Explanation

The multipath statement under BGP allows multiple equal-cost BGP paths to be installed in the forwarding table, enabling load balancing. It does not affect advertisement of routes or other protocols. It is specific to BGP.

Question 47Service Provider Routing and Switching

Which command displays the BGP routes received from a specific neighbor before policy is applied?

  1. show route advertised-protocol bgp <neighbor>
  2. show route protocol bgp
  3. show bgp neighbor <neighbor>
  4. show route receive-protocol bgp <neighbor> Correct answer.

Explanation

The show route receive-protocol bgp command displays routes received from a specific BGP neighbor before import policy is applied. The show route protocol bgp command shows BGP routes in the routing table after policy. The advertised-protocol command shows routes advertised to a neighbor.

Question 48Service Provider Routing and Switching

An engineer needs to configure a Junos router to prefer OSPF routes over IS-IS routes for the same prefix. Which action accomplishes this?

  1. Set the metric of OSPF routes to a higher value than IS-IS.
  2. Set the metric of OSPF routes to a lower value than IS-IS.
  3. Set the preference of OSPF routes to a higher value than IS-IS.
  4. Set the preference of OSPF routes to a lower value than IS-IS. Correct answer.

Explanation

In Junos, a lower preference value is preferred over a higher one. To prefer OSPF routes over IS-IS, set the OSPF preference to a value lower than the IS-IS preference. Metric is used within a protocol and does not affect selection between protocols.

Question 49Service Provider Routing and Switching

Which statement describes the role of the Junos 'route-preference' value when two protocols advertise the same prefix?

  1. The route with the lower preference value is preferred. Correct answer.
  2. The route with the higher metric is preferred.
  3. The route with the lower metric is preferred.
  4. The route with the higher preference value is preferred.

Explanation

Junos uses preference to select between routes from different protocols. A lower preference value indicates a more preferred route. Metric is used to select between routes from the same protocol.

Question 50Service Provider Routing and Switching

A service provider uses BGP labeled unicast to distribute labels for prefixes. Which statement describes how this differs from LDP?

  1. BGP labeled unicast distributes labels for BGP prefixes, while LDP distributes labels for IGP prefixes. Correct answer.
  2. BGP labeled unicast is used only for IPv6, while LDP is used for IPv4.
  3. BGP labeled unicast requires RSVP for label distribution, while LDP does not.
  4. BGP labeled unicast distributes labels for IGP prefixes, while LDP distributes labels for BGP prefixes.

Explanation

BGP labeled unicast (BGP-LU) distributes MPLS labels along with BGP prefixes, allowing MPLS forwarding for BGP routes. LDP distributes labels for IGP-learned prefixes. BGP-LU does not require RSVP and can be used for IPv4 and IPv6.