Cisco CCNP 350-401 ENCOR Multicast: RPF, PIM-SM, IGMPv2/v3, SSM, Bidir, and MSDP Practice Test 2

 

Topic 12 Practice Test 2 covers Multicast: RPF, PIM-SM, IGMPv2/v3, SSM, Bidir, and MSDP for Cisco 350-401 ENCOR. For broader exam preparation, review the Cisco 350-401 ENCOR Exam Dumps. Every option includes focused technical reasoning explaining both the Cisco enterprise networking concept and its fit to the scenario.

Question 1

Multicast packets arrive on an unexpected interface and are being discarded before downstream replication, but the current design is not providing the expected result. The production operations group wants a component that uses the unicast routing table or multicast routing information to prevent loops and duplicate forwarding. Which change should be made? Choose ONE.

1. PIM SSM without RP
2. RPF neighbor change after unicast routing change
3. IGMPv2 leave processing
4. RPF check

Correct Answer(s)

 

D

Rationale

1. Use PIM SSM without RP to build the tree directly toward the named source instead of using an RP. Its mechanism relies on receiver source information, typically from IGMPv3, to create (S,G) joins. The current scenario requires RPF check; PIM SSM without RP solves a different design issue.
2. RPF neighbor change after unicast routing change is meant to recalculate the valid upstream multicast interface when the route toward the source changes. Use it when an IGP reconvergence moves the best path to the multicast source onto a different interface. This stem calls for RPF check; RPF neighbor change after unicast routing change addresses another operational need.
3. Use IGMPv2 leave processing to notify the local router that a host no longer wants a group so membership can be pruned after verification. Its mechanism uses leave messages and group-specific queries to determine whether any receivers remain. The current scenario requires RPF check; IGMPv2 leave processing solves a different design issue.
4. Choose RPF check. Its function is to uses the unicast routing table or multicast routing information to prevent loops and duplicate forwarding. Here the required outcome is to accept multicast traffic only when it arrives on the interface that unicast routing considers the path back toward the source. This capability places RPF check at the proper layer; alternatives do not.

 

Question 2

An asm deployment needs a common meeting point for senders and receivers, but the current design is not providing the expected result. The platform team wants a component that anchors (*,G) state so receivers can join a group before source-specific trees are established. Which change should be made? Choose ONE.

1. PIM Join toward upstream neighbor
2. PIM sparse-mode RP
3. multicast TTL scope check
4. IGMPv3 INCLUDE mode

Correct Answer(s)

 

B

Rationale

1. The role of PIM Join toward upstream neighbor is to create or refresh multicast forwarding state toward the source or RP. It is useful when a downstream router has interested receivers and must extend the multicast tree upstream. Here the design needs PIM sparse-mode RP; this choice instead solves an adjacent problem.
2. Choose PIM sparse-mode RP. Its function is to anchors (*,G) state so receivers can join a group before source-specific trees are established. Here the required outcome is to provide the rendezvous point used to build the initial shared tree for ASM receivers and sources. This capability places PIM sparse-mode RP at the proper layer; alternatives do not.
3. Use multicast TTL scope check to verify packets are not expiring before reaching intended receivers. Its mechanism examines IP TTL handling because multicast forwarding decrements TTL like other IP traffic. The current scenario requires PIM sparse-mode RP; multicast TTL scope check solves a different design issue.
4. IGMPv3 INCLUDE mode belongs where a host should receive group traffic from one approved source and reject other senders. It helps to request traffic only from explicitly listed multicast sources. The stem instead requires PIM sparse-mode RP, so IGMPv3 INCLUDE mode does not meet the decisive condition.

 

Question 3

A new source begins sending in a pim-sm domain before the rp has native source-tree state, but the current design is not providing the expected result. The network operations group wants a component that encapsulates early multicast packets to the RP until native forwarding can take over. Which change should be made? Choose ONE.

1. PIM Register
2. PIM Prune
3. RPF check
4. IGMPv3 EXCLUDE mode

Correct Answer(s)

 

A

Rationale

1. Choose PIM Register. Its function is to encapsulates early multicast packets to the RP until native forwarding can take over. Here the required outcome is to carry initial source traffic from the first-hop router toward the RP. This capability places PIM Register at the proper layer; alternatives do not.
2. PIM Prune can be appropriate because it signals that a downstream path no longer needs traffic for the relevant multicast state. Apply it where a branch has no remaining receivers and should stop consuming WAN bandwidth. This case depends on PIM Register, leaving PIM Prune mismatched to the requirement.
3. RPF check belongs where multicast packets arrive on an unexpected interface and are being discarded before downstream replication. It helps to accept multicast traffic only when it arrives on the interface that unicast routing considers the path back toward the source. The stem instead requires PIM Register, so RPF check does not meet the decisive condition.
4. IGMPv3 EXCLUDE mode is meant to receive a group from all sources except an identified list. Use it when a receiver wants broad ASM-style group traffic but must block a small set of sources. This stem calls for PIM Register; IGMPv3 EXCLUDE mode addresses another operational need.

 

Question 4

The last-hop router has joined an asm group but has not selected a specific source tree, but the current design is not providing the expected result. The application team wants a component that builds the initial tree toward the RP for any source in the group. Which change should be made? Choose ONE.

1. Anycast RP with MSDP
2. (*,G) shared-tree state
3. PIM sparse-mode RP
4. SSM group range

Correct Answer(s)

 

B

Rationale

1. Anycast RP with MSDP belongs where the PIM-SM design requires RP resiliency across separate locations. It helps to provide redundant RP addresses while synchronizing active-source knowledge between RP peers. The stem instead requires (*,G) shared-tree state, so Anycast RP with MSDP does not meet the decisive condition.
2. Choose (*,G) shared-tree state. Its function is to builds the initial tree toward the RP for any source in the group. Here the required outcome is to represent receiver interest in a multicast group regardless of a particular source. This capability places (*,G) shared-tree state at the proper layer; alternatives do not.
3. Use PIM sparse-mode RP to provide the rendezvous point used to build the initial shared tree for ASM receivers and sources. Its mechanism anchors (*,G) state so receivers can join a group before source-specific trees are established. The current scenario requires (*,G) shared-tree state; PIM sparse-mode RP solves a different design issue.
4. SSM group range can be appropriate because it eliminates RP discovery for SSM traffic and builds (S,G) state directly toward the source. Apply it where the application can identify the authorized source address and wants simpler source-specific forwarding. This case depends on (*,G) shared-tree state, leaving SSM group range mismatched to the requirement.

 

Question 5

The router has switched from the rp-rooted shared tree to a source-specific path, but the current design is not providing the expected result. The enterprise architect wants a component that creates source-specific state that follows a shortest path toward the source. Which change should be made? Choose ONE.

1. MSDP source-active message
2. PIM Register
3. (S,G) source-tree state
4. PIM SSM without RP

Correct Answer(s)

 

C

Rationale

1. Use MSDP source-active message to advertise knowledge of an active multicast source between PIM-SM domains or RP peers. Its mechanism carries source/group information so another RP can learn about remote active sources. The current scenario requires (S,G) source-tree state; MSDP source-active message solves a different design issue.
2. The role of PIM Register is to carry initial source traffic from the first-hop router toward the RP. It is useful when a new source begins sending in a PIM-SM domain before the RP has native source-tree state. Here the design needs (S,G) source-tree state; this choice instead solves an adjacent problem.
3. Choose (S,G) source-tree state. Its function is to creates source-specific state that follows a shortest path toward the source. Here the required outcome is to forward multicast for one specific source and group pair. This capability places (S,G) source-tree state at the proper layer; alternatives do not.
4. The role of PIM SSM without RP is to build the tree directly toward the named source instead of using an RP. It is useful when an SSM application should not depend on rendezvous-point infrastructure. Here the design needs (S,G) source-tree state; this choice instead solves an adjacent problem.

 

Question 6

A host wants to join an asm group but does not need to specify the source, but the current design is not providing the expected result. The site reliability team wants a component that lets the local multicast router learn that receivers exist on the LAN. Which change should be made? Choose ONE.

1. PIM bidirectional shared tree
2. IGMPv2 membership report
3. (*,G) shared-tree state
4. PIM Join toward upstream neighbor

Correct Answer(s)

 

B

Rationale

1. PIM bidirectional shared tree is meant to use one shared tree rooted at the RP for traffic in both directions without source-tree switchover. Use it when many-to-many applications have numerous sources and a shared-tree design is preferred. This stem calls for IGMPv2 membership report; PIM bidirectional shared tree addresses another operational need.
2. Choose IGMPv2 membership report. Its function is to lets the local multicast router learn that receivers exist on the LAN. Here the required outcome is to signal host interest in receiving traffic for an IPv4 multicast group. This capability places IGMPv2 membership report at the proper layer; alternatives do not.
3. (*,G) shared-tree state works by builds the initial tree toward the RP for any source in the group. It fits where the last-hop router has joined an ASM group but has not selected a specific source tree. The required function here is IGMPv2 membership report, so this option targets the wrong condition.
4. PIM Join toward upstream neighbor is meant to create or refresh multicast forwarding state toward the source or RP. Use it when a downstream router has interested receivers and must extend the multicast tree upstream. This stem calls for IGMPv2 membership report; PIM Join toward upstream neighbor addresses another operational need.

 

Question 7

A receiver stops an iptv channel and the last-hop router should remove unused forwarding state promptly, but the current design is not providing the expected result. The security engineering group wants a component that uses leave messages and group-specific queries to determine whether any receivers remain. Which change should be made? Choose ONE.

1. PIM designated router
2. (S,G) source-tree state
3. IGMPv2 leave processing
4. PIM Prune

Correct Answer(s)

 

C

Rationale

1. The role of PIM designated router is to act for directly connected hosts on a multiaccess network when sending joins or registering sources. It is useful when several PIM routers share one Ethernet segment with multicast sources and receivers. Here the design needs IGMPv2 leave processing; this choice instead solves an adjacent problem.
2. (S,G) source-tree state can be appropriate because it creates source-specific state that follows a shortest path toward the source. Apply it where the router has switched from the RP-rooted shared tree to a source-specific path. This case depends on IGMPv2 leave processing, leaving (S,G) source-tree state mismatched to the requirement.
3. Choose IGMPv2 leave processing. Its function is to uses leave messages and group-specific queries to determine whether any receivers remain. Here the required outcome is to notify the local router that a host no longer wants a group so membership can be pruned after verification. This capability places IGMPv2 leave processing at the proper layer; alternatives do not.
4. PIM Prune works by signals that a downstream path no longer needs traffic for the relevant multicast state. It fits where a branch has no remaining receivers and should stop consuming WAN bandwidth. The required function here is IGMPv2 leave processing, so this option targets the wrong condition.

 

Question 8

A host should receive group traffic from one approved source and reject other senders, but the current design is not providing the expected result. The branch deployment team wants a component that lets receivers express source-specific interest needed for SSM behavior. Which change should be made? Choose ONE.

1. last-hop router group state
2. IGMPv2 membership report
3. IGMPv3 INCLUDE mode
4. Anycast RP with MSDP

Correct Answer(s)

 

C

Rationale

1. last-hop router group state works by combines IGMP information from hosts with PIM signaling toward the multicast distribution tree. It fits where hosts joined successfully on a VLAN but upstream multicast state is missing. The required function here is IGMPv3 INCLUDE mode, so this option targets the wrong condition.
2. IGMPv2 membership report belongs where a host wants to join an ASM group but does not need to specify the source. It helps to signal host interest in receiving traffic for an IPv4 multicast group. The stem instead requires IGMPv3 INCLUDE mode, so IGMPv2 membership report does not meet the decisive condition.
3. Choose IGMPv3 INCLUDE mode. Its function is to lets receivers express source-specific interest needed for SSM behavior. Here the required outcome is to request traffic only from explicitly listed multicast sources. This capability places IGMPv3 INCLUDE mode at the proper layer; alternatives do not.
4. Anycast RP with MSDP can be appropriate because it uses the same RP address on multiple routers and MSDP source-active messages so ASM sources are known across them. Apply it where the PIM-SM design requires RP resiliency across separate locations. This case depends on IGMPv3 INCLUDE mode, leaving Anycast RP with MSDP mismatched to the requirement.

 

Question 9

A receiver wants broad asm-style group traffic but must block a small set of sources, but the current design is not providing the expected result. The support organization wants a component that expresses source filtering where particular senders are excluded. Which change should be made? Choose ONE.

1. RPF neighbor change after unicast routing change
2. IGMPv2 leave processing
3. MSDP source-active message
4. IGMPv3 EXCLUDE mode

Correct Answer(s)

 

D

Rationale

1. The role of RPF neighbor change after unicast routing change is to recalculate the valid upstream multicast interface when the route toward the source changes. It is useful when an IGP reconvergence moves the best path to the multicast source onto a different interface. Here the design needs IGMPv3 EXCLUDE mode; this choice instead solves an adjacent problem.
2. IGMPv2 leave processing is meant to notify the local router that a host no longer wants a group so membership can be pruned after verification. Use it when a receiver stops an IPTV channel and the last-hop router should remove unused forwarding state promptly. This stem calls for IGMPv3 EXCLUDE mode; IGMPv2 leave processing addresses another operational need.
3. The role of MSDP source-active message is to advertise knowledge of an active multicast source between PIM-SM domains or RP peers. It is useful when receivers behind one RP must discover a source registered with another RP. Here the design needs IGMPv3 EXCLUDE mode; this choice instead solves an adjacent problem.
4. Choose IGMPv3 EXCLUDE mode. Its function is to expresses source filtering where particular senders are excluded. Here the required outcome is to receive a group from all sources except an identified list. This capability places IGMPv3 EXCLUDE mode at the proper layer; alternatives do not.

 

Question 10

The application can identify the authorized source address and wants simpler source-specific forwarding, but the current design is not providing the expected result. The cloud engineering team wants a component that eliminates RP discovery for SSM traffic and builds (S,G) state directly toward the source. Which change should be made? Choose ONE.

1. multicast TTL scope check
2. IGMPv3 INCLUDE mode
3. PIM bidirectional shared tree
4. SSM group range

Correct Answer(s)

 

D

Rationale

1. multicast TTL scope check is meant to verify packets are not expiring before reaching intended receivers. Use it when routing and PIM state are correct but packets consistently stop after a fixed number of routed hops. This stem calls for SSM group range; multicast TTL scope check addresses another operational need.
2. IGMPv3 INCLUDE mode works by lets receivers express source-specific interest needed for SSM behavior. It fits where a host should receive group traffic from one approved source and reject other senders. The required function here is SSM group range, so this option targets the wrong condition.
3. Use PIM bidirectional shared tree to use one shared tree rooted at the RP for traffic in both directions without source-tree switchover. Its mechanism maintains bidirectional group forwarding around a designated forwarder model. The current scenario requires SSM group range; PIM bidirectional shared tree solves a different design issue.
4. Choose SSM group range. Its function is to eliminates RP discovery for SSM traffic and builds (S,G) state directly toward the source. Here the required outcome is to use source-specific multicast semantics where the receiver identifies both source and group. This capability places SSM group range at the proper layer; alternatives do not.

 

Question 11

An ssm application should not depend on rendezvous-point infrastructure, but the current design is not providing the expected result. The infrastructure team wants a component that relies on receiver source information, typically from IGMPv3, to create (S,G) joins. Which change should be made? Choose ONE.

1. PIM SSM without RP
2. RPF check
3. IGMPv3 EXCLUDE mode
4. PIM designated router

Correct Answer(s)

 

A

Rationale

1. Choose PIM SSM without RP. Its function is to relies on receiver source information, typically from IGMPv3, to create (S,G) joins. Here the required outcome is to build the tree directly toward the named source instead of using an RP. This capability places PIM SSM without RP at the proper layer; alternatives do not.
2. RPF check works by uses the unicast routing table or multicast routing information to prevent loops and duplicate forwarding. It fits where multicast packets arrive on an unexpected interface and are being discarded before downstream replication. The required function here is PIM SSM without RP, so this option targets the wrong condition.
3. The role of IGMPv3 EXCLUDE mode is to receive a group from all sources except an identified list. It is useful when a receiver wants broad ASM-style group traffic but must block a small set of sources. Here the design needs PIM SSM without RP; this choice instead solves an adjacent problem.
4. PIM designated router is meant to act for directly connected hosts on a multiaccess network when sending joins or registering sources. Use it when several PIM routers share one Ethernet segment with multicast sources and receivers. This stem calls for PIM SSM without RP; PIM designated router addresses another operational need.

 

Question 12

A downstream router has interested receivers and must extend the multicast tree upstream, but the current design is not providing the expected result. The architecture review board wants a component that sends control-plane join messages in the upstream direction selected by RPF. Which change should be made? Choose ONE.

1. PIM Join toward upstream neighbor
2. PIM sparse-mode RP
3. SSM group range
4. last-hop router group state

Correct Answer(s)

 

A

Rationale

1. Choose PIM Join toward upstream neighbor. Its function is to sends control-plane join messages in the upstream direction selected by RPF. Here the required outcome is to create or refresh multicast forwarding state toward the source or RP. This capability places PIM Join toward upstream neighbor at the proper layer; alternatives do not.
2. PIM sparse-mode RP is meant to provide the rendezvous point used to build the initial shared tree for ASM receivers and sources. Use it when an ASM deployment needs a common meeting point for senders and receivers. This stem calls for PIM Join toward upstream neighbor; PIM sparse-mode RP addresses another operational need.
3. SSM group range belongs where the application can identify the authorized source address and wants simpler source-specific forwarding. It helps to use source-specific multicast semantics where the receiver identifies both source and group. The stem instead requires PIM Join toward upstream neighbor, so SSM group range does not meet the decisive condition.
4. last-hop router group state belongs where hosts joined successfully on a VLAN but upstream multicast state is missing. It helps to track local receiver membership and translate it into upstream PIM joins. The stem instead requires PIM Join toward upstream neighbor, so last-hop router group state does not meet the decisive condition.

 

Question 13

A branch has no remaining receivers and should stop consuming wan bandwidth, but the current design is not providing the expected result. The production operations group wants a component that signals that a downstream path no longer needs traffic for the relevant multicast state. Which change should be made? Choose ONE.

1. PIM Register
2. PIM Prune
3. PIM SSM without RP
4. RPF neighbor change after unicast routing change

Correct Answer(s)

 

B

Rationale

1. Use PIM Register to carry initial source traffic from the first-hop router toward the RP. Its mechanism encapsulates early multicast packets to the RP until native forwarding can take over. The current scenario requires PIM Prune; PIM Register solves a different design issue.
2. Choose PIM Prune. Its function is to signals that a downstream path no longer needs traffic for the relevant multicast state. Here the required outcome is to remove an unnecessary branch of a multicast distribution tree. This capability places PIM Prune at the proper layer; alternatives do not.
3. Use PIM SSM without RP to build the tree directly toward the named source instead of using an RP. Its mechanism relies on receiver source information, typically from IGMPv3, to create (S,G) joins. The current scenario requires PIM Prune; PIM SSM without RP solves a different design issue.
4. RPF neighbor change after unicast routing change is meant to recalculate the valid upstream multicast interface when the route toward the source changes. Use it when an IGP reconvergence moves the best path to the multicast source onto a different interface. This stem calls for PIM Prune; RPF neighbor change after unicast routing change addresses another operational need.

 

Question 14

The pim-sm design requires rp resiliency across separate locations, but the current design is not providing the expected result. The platform team wants a component that uses the same RP address on multiple routers and MSDP source-active messages so ASM sources are known across them. Which change should be made? Choose ONE.

1. Anycast RP with MSDP
2. (*,G) shared-tree state
3. PIM Join toward upstream neighbor
4. multicast TTL scope check

Correct Answer(s)

 

A

Rationale

1. Choose Anycast RP with MSDP. Its function is to uses the same RP address on multiple routers and MSDP source-active messages so ASM sources are known across them. Here the required outcome is to provide redundant RP addresses while synchronizing active-source knowledge between RP peers. This capability places Anycast RP with MSDP at the proper layer; alternatives do not.
2. (*,G) shared-tree state can be appropriate because it builds the initial tree toward the RP for any source in the group. Apply it where the last-hop router has joined an ASM group but has not selected a specific source tree. This case depends on Anycast RP with MSDP, leaving (*,G) shared-tree state mismatched to the requirement.
3. The role of PIM Join toward upstream neighbor is to create or refresh multicast forwarding state toward the source or RP. It is useful when a downstream router has interested receivers and must extend the multicast tree upstream. Here the design needs Anycast RP with MSDP; this choice instead solves an adjacent problem.
4. Use multicast TTL scope check to verify packets are not expiring before reaching intended receivers. Its mechanism examines IP TTL handling because multicast forwarding decrements TTL like other IP traffic. The current scenario requires Anycast RP with MSDP; multicast TTL scope check solves a different design issue.

 

Question 15

Receivers behind one rp must discover a source registered with another rp, but the current design is not providing the expected result. The network operations group wants a component that carries source/group information so another RP can learn about remote active sources. Which change should be made? Choose ONE.

1. MSDP source-active message
2. (S,G) source-tree state
3. PIM Prune
4. RPF check

Correct Answer(s)

 

A

Rationale

1. Choose MSDP source-active message. Its function is to carries source/group information so another RP can learn about remote active sources. Here the required outcome is to advertise knowledge of an active multicast source between PIM-SM domains or RP peers. This capability places MSDP source-active message at the proper layer; alternatives do not.
2. (S,G) source-tree state belongs where the router has switched from the RP-rooted shared tree to a source-specific path. It helps to forward multicast for one specific source and group pair. The stem instead requires MSDP source-active message, so (S,G) source-tree state does not meet the decisive condition.
3. PIM Prune can be appropriate because it signals that a downstream path no longer needs traffic for the relevant multicast state. Apply it where a branch has no remaining receivers and should stop consuming WAN bandwidth. This case depends on MSDP source-active message, leaving PIM Prune mismatched to the requirement.
4. RPF check belongs where multicast packets arrive on an unexpected interface and are being discarded before downstream replication. It helps to accept multicast traffic only when it arrives on the interface that unicast routing considers the path back toward the source. The stem instead requires MSDP source-active message, so RPF check does not meet the decisive condition.

 

Question 16

Many-to-many applications have numerous sources and a shared-tree design is preferred, but the current design is not providing the expected result. The application team wants a component that maintains bidirectional group forwarding around a designated forwarder model. Which change should be made? Choose ONE.

1. IGMPv2 membership report
2. Anycast RP with MSDP
3. PIM bidirectional shared tree
4. PIM sparse-mode RP

Correct Answer(s)

 

C

Rationale

1. IGMPv2 membership report works by lets the local multicast router learn that receivers exist on the LAN. It fits where a host wants to join an ASM group but does not need to specify the source. The required function here is PIM bidirectional shared tree, so this option targets the wrong condition.
2. Anycast RP with MSDP belongs where the PIM-SM design requires RP resiliency across separate locations. It helps to provide redundant RP addresses while synchronizing active-source knowledge between RP peers. The stem instead requires PIM bidirectional shared tree, so Anycast RP with MSDP does not meet the decisive condition.
3. Choose PIM bidirectional shared tree. Its function is to maintains bidirectional group forwarding around a designated forwarder model. Here the required outcome is to use one shared tree rooted at the RP for traffic in both directions without source-tree switchover. This capability places PIM bidirectional shared tree at the proper layer; alternatives do not.
4. Use PIM sparse-mode RP to provide the rendezvous point used to build the initial shared tree for ASM receivers and sources. Its mechanism anchors (*,G) state so receivers can join a group before source-specific trees are established. The current scenario requires PIM bidirectional shared tree; PIM sparse-mode RP solves a different design issue.

 

Question 17

Several pim routers share one ethernet segment with multicast sources and receivers, but the current design is not providing the expected result. The enterprise architect wants a component that elects one PIM router on the LAN to perform first-hop or last-hop control duties. Which change should be made? Choose ONE.

1. IGMPv2 leave processing
2. MSDP source-active message
3. PIM Register
4. PIM designated router

Correct Answer(s)

 

D

Rationale

1. The role of IGMPv2 leave processing is to notify the local router that a host no longer wants a group so membership can be pruned after verification. It is useful when a receiver stops an IPTV channel and the last-hop router should remove unused forwarding state promptly. Here the design needs PIM designated router; this choice instead solves an adjacent problem.
2. Use MSDP source-active message to advertise knowledge of an active multicast source between PIM-SM domains or RP peers. Its mechanism carries source/group information so another RP can learn about remote active sources. The current scenario requires PIM designated router; MSDP source-active message solves a different design issue.
3. The role of PIM Register is to carry initial source traffic from the first-hop router toward the RP. It is useful when a new source begins sending in a PIM-SM domain before the RP has native source-tree state. Here the design needs PIM designated router; this choice instead solves an adjacent problem.
4. Choose PIM designated router. Its function is to elects one PIM router on the LAN to perform first-hop or last-hop control duties. Here the required outcome is to act for directly connected hosts on a multiaccess network when sending joins or registering sources. This capability places PIM designated router at the proper layer; alternatives do not.

 

Question 18

Hosts joined successfully on a vlan but upstream multicast state is missing, but the current design is not providing the expected result. The site reliability team wants a component that combines IGMP information from hosts with PIM signaling toward the multicast distribution tree. Which change should be made? Choose ONE.

1. IGMPv3 INCLUDE mode
2. last-hop router group state
3. PIM bidirectional shared tree
4. (*,G) shared-tree state

Correct Answer(s)

 

B

Rationale

1. IGMPv3 INCLUDE mode can be appropriate because it lets receivers express source-specific interest needed for SSM behavior. Apply it where a host should receive group traffic from one approved source and reject other senders. This case depends on last-hop router group state, leaving IGMPv3 INCLUDE mode mismatched to the requirement.
2. Choose last-hop router group state. Its function is to combines IGMP information from hosts with PIM signaling toward the multicast distribution tree. Here the required outcome is to track local receiver membership and translate it into upstream PIM joins. This capability places last-hop router group state at the proper layer; alternatives do not.
3. PIM bidirectional shared tree is meant to use one shared tree rooted at the RP for traffic in both directions without source-tree switchover. Use it when many-to-many applications have numerous sources and a shared-tree design is preferred. This stem calls for last-hop router group state; PIM bidirectional shared tree addresses another operational need.
4. (*,G) shared-tree state works by builds the initial tree toward the RP for any source in the group. It fits where the last-hop router has joined an ASM group but has not selected a specific source tree. The required function here is last-hop router group state, so this option targets the wrong condition.

 

Question 19

An igp reconvergence moves the best path to the multicast source onto a different interface, but the current design is not providing the expected result. The security engineering group wants a component that ties multicast upstream selection to current routing information so topology changes can alter the RPF path. Which change should be made? Choose ONE.

1. IGMPv3 EXCLUDE mode
2. PIM designated router
3. (S,G) source-tree state
4. RPF neighbor change after unicast routing change

Correct Answer(s)

 

D

Rationale

1. Use IGMPv3 EXCLUDE mode to receive a group from all sources except an identified list. Its mechanism expresses source filtering where particular senders are excluded. The current scenario requires RPF neighbor change after unicast routing change; IGMPv3 EXCLUDE mode solves a different design issue.
2. The role of PIM designated router is to act for directly connected hosts on a multiaccess network when sending joins or registering sources. It is useful when several PIM routers share one Ethernet segment with multicast sources and receivers. Here the design needs RPF neighbor change after unicast routing change; this choice instead solves an adjacent problem.
3. (S,G) source-tree state can be appropriate because it creates source-specific state that follows a shortest path toward the source. Apply it where the router has switched from the RP-rooted shared tree to a source-specific path. This case depends on RPF neighbor change after unicast routing change, leaving (S,G) source-tree state mismatched to the requirement.
4. Choose RPF neighbor change after unicast routing change. Its function is to ties multicast upstream selection to current routing information so topology changes can alter the RPF path. Here the required outcome is to recalculate the valid upstream multicast interface when the route toward the source changes. This capability places RPF neighbor change after unicast routing change at the proper layer; alternatives do not.

 

Question 20

Routing and pim state are correct but packets consistently stop after a fixed number of routed hops, but the current design is not providing the expected result. The branch deployment team wants a component that examines IP TTL handling because multicast forwarding decrements TTL like other IP traffic. Which change should be made? Choose ONE.

1. SSM group range
2. last-hop router group state
3. multicast TTL scope check
4. IGMPv2 membership report

Correct Answer(s)

 

C

Rationale

1. SSM group range works by eliminates RP discovery for SSM traffic and builds (S,G) state directly toward the source. It fits where the application can identify the authorized source address and wants simpler source-specific forwarding. The required function here is multicast TTL scope check, so this option targets the wrong condition.
2. last-hop router group state works by combines IGMP information from hosts with PIM signaling toward the multicast distribution tree. It fits where hosts joined successfully on a VLAN but upstream multicast state is missing. The required function here is multicast TTL scope check, so this option targets the wrong condition.
3. Choose multicast TTL scope check. Its function is to examines IP TTL handling because multicast forwarding decrements TTL like other IP traffic. Here the required outcome is to verify packets are not expiring before reaching intended receivers. This capability places multicast TTL scope check at the proper layer; alternatives do not.
4. IGMPv2 membership report belongs where a host wants to join an ASM group but does not need to specify the source. It helps to signal host interest in receiving traffic for an IPv4 multicast group. The stem instead requires multicast TTL scope check, so IGMPv2 membership report does not meet the decisive condition.

• < Cisco CCNP 350-401 ENCOR Multicast: RPF, PIM-SM, IGMPv2/v3, SSM, Bidir, and MSDP Practice Test 1
• Cisco CCNP 350-401 ENCOR Diagnostics, Debugs, Ping/Traceroute, SNMP, and Syslog Practice Test 1 >