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350-501 · topic practice

MPLS and Segment Routing practice questions

Practise Cisco SPCOR / CCNP Service Provider Core 350-501 MPLS and Segment Routing practice questions — original exam-style scenarios with answer choices, explanations, and analysis of common mistakes.

Courseiva uses original exam-style practice questions designed for learning and revision. The goal is to understand the concepts, recognise exam patterns, and improve through explanations — not memorise copied exam dumps.

Reviewed byJohnson Ajibi· MSc IT Security

20 questionsDomain: MPLS and Segment Routing

Practice 10 questions Browse domain →

What the exam tests

What to know about MPLS and Segment Routing

Routing questions usually test route selection (administrative distance, metric), how static routes are configured and when they are preferred over dynamic routing.

Administrative distance comparing routing sources.

Static route configuration: next-hop vs exit interface.

Default route propagation and the gateway of last resort.

Recursive routing table lookups.

Watch out for

Common MPLS and Segment Routing exam traps

▸Lower administrative distance wins when two routing sources have the same prefix.
▸A static route with an exit interface creates a directly-connected dependency.
▸The gateway of last resort is set by the default route, not automatically.
▸Metric is only compared within the same routing protocol.

Practice set

MPLS and Segment Routing questions

20 questions · select your answer, then reveal the explanation

Question 1mediummultiple choice

Review the full OSPF breakdown →

An engineer is troubleshooting an MPLS L3VPN where customers behind CE1 cannot reach a specific prefix behind CE2. The PE routers are using OSPF as the IGP and LDP for label distribution. On PE2, the prefix is present in the VRF routing table, but not in the VRF forwarding table. What is the most likely cause?

Trap 1: MTU mismatch is causing the VPN label to be dropped.

MTU mismatch would cause packet drops, not prevent the route from being installed in the forwarding table.

Trap 2: OSPF is not redistributing the BGP routes into the IGP on PE2.

OSPF redistribution is not required for MPLS label allocation; labels are assigned via LDP.

Trap 3: The VRF is not properly configured on PE2's interface toward CE2.

If the VRF were misconfigured, the route would not appear in the VRF routing table either.

Study all MPLS and Segment Routing common traps →

A
MTU mismatch is causing the VPN label to be dropped.
Why wrong: MTU mismatch would cause packet drops, not prevent the route from being installed in the forwarding table.
B
OSPF is not redistributing the BGP routes into the IGP on PE2.
Why wrong: OSPF redistribution is not required for MPLS label allocation; labels are assigned via LDP.
C
The VRF is not properly configured on PE2's interface toward CE2.
Why wrong: If the VRF were misconfigured, the route would not appear in the VRF routing table either.
D
The route is missing a label in the LFIB on PE2.
If the label is missing, the route cannot be installed in the VRF forwarding table.

Full breakdown with real-world context →

Question 2hardmultiple choice

Read the full MPLS explanation →

A service provider is designing a new MPLS core network using Segment Routing with MPLS data plane. They require traffic engineering capabilities to optimize bandwidth utilization. Which technology should be used to compute optimal paths based on IGP link attributes and bandwidth constraints?

Trap 1: RSVP-TE with FRR

RSVP-TE can do traffic engineering but is not specific to Segment Routing; the question asks for a technology that works with SR.

Trap 2: LDP over SR

LDP is not used for traffic engineering; it distributes labels for IGP shortest paths.

Trap 3: OSPF with MPLS-TE extensions

OSPF-TE provides link attributes but does not compute paths; a separate path computation element is needed.

Study all MPLS and Segment Routing common traps →

A
RSVP-TE with FRR
Why wrong: RSVP-TE can do traffic engineering but is not specific to Segment Routing; the question asks for a technology that works with SR.
B
LDP over SR
Why wrong: LDP is not used for traffic engineering; it distributes labels for IGP shortest paths.
C
SR-TE (Segment Routing Traffic Engineering)
SR-TE computes paths using segment lists and can enforce bandwidth constraints.
D
OSPF with MPLS-TE extensions
Why wrong: OSPF-TE provides link attributes but does not compute paths; a separate path computation element is needed.

Full breakdown with real-world context →

Question 3easymultiple choice

Read the full MPLS explanation →

An engineer is deploying MPLS in the core and wants to ensure that all core routers use the same label for a specific prefix, regardless of which router originated it. Which MPLS label allocation mode should be used?

Trap 1: Per-interface label mode

Per-interface assigns a different label for each interface, not consistent across routers.

Trap 2: Per-next-hop label mode

Per-next-hop assigns labels based on next hop, not per prefix.

Trap 3: Per-VRF label mode

Per-VRF is for VPNs, not for core prefix labels.

Study all MPLS and Segment Routing common traps →

A
Per-interface label mode
Why wrong: Per-interface assigns a different label for each interface, not consistent across routers.
B
Per-next-hop label mode
Why wrong: Per-next-hop assigns labels based on next hop, not per prefix.
C
Per-prefix label mode
Per-prefix allocates one label per prefix, ensuring same label across all routers.
D
Per-VRF label mode
Why wrong: Per-VRF is for VPNs, not for core prefix labels.

Full breakdown with real-world context →

Question 4mediummultiple choice

Review the full OSPF breakdown →

During an MPLS network migration from LDP to Segment Routing, an engineer notices that some routers are not advertising Prefix-SIDs for certain loopbacks. The IGP is OSPF. What configuration is required on these routers to advertise Prefix-SIDs?

Trap 1: Enable 'mpls ldp autoconfig' on the loopback interface.

This is for LDP, not SR.

Trap 2: Enable 'segment-routing mpls' globally and configure 'prefix-sid…

The prefix-sid is configured under the OSPF router process, not the interface.

Trap 3: Configure 'segment-routing mpls set-adjacency-sid' on the loopback.

Adjacency-SIDs are for interfaces, not loopbacks.

Study all MPLS and Segment Routing common traps →

A
Enable 'mpls ldp autoconfig' on the loopback interface.
Why wrong: This is for LDP, not SR.
B
Enable 'segment-routing mpls' globally and configure 'prefix-sid index' under the loopback interface.
Why wrong: The prefix-sid is configured under the OSPF router process, not the interface.
C
Configure 'segment-routing mpls set-adjacency-sid' on the loopback.
Why wrong: Adjacency-SIDs are for interfaces, not loopbacks.
D
Configure 'segment-routing mpls' globally and assign a SID index under the OSPF router process for the loopback.
This enables SR globally and assigns the Prefix-SID under OSPF.

Full breakdown with real-world context →

Question 5hardmultiple choice

Read the full MPLS explanation →

A service provider is deploying a new MPLS core with Segment Routing and requires fast convergence upon link failure. They plan to use TI-LFA (Topology Independent Loop-Free Alternate). What is a prerequisite for TI-LFA to provide protection against any single link failure?

Trap 1: BGP-LU must be enabled for label distribution.

BGP-LU is not required for TI-LFA.

Trap 2: LDP must be enabled on all interfaces.

TI-LFA is independent of LDP.

Trap 3: RSVP-TE must be configured with FRR.

TI-LFA does not use RSVP-TE.

Study all MPLS and Segment Routing common traps →

A
IGP must be a link-state protocol with complete topology information (OSPF or IS-IS).
TI-LFA uses the link-state database to compute backup paths.
B
BGP-LU must be enabled for label distribution.
Why wrong: BGP-LU is not required for TI-LFA.
C
LDP must be enabled on all interfaces.
Why wrong: TI-LFA is independent of LDP.
D
RSVP-TE must be configured with FRR.
Why wrong: TI-LFA does not use RSVP-TE.

Full breakdown with real-world context →

Question 6mediummulti select

Read the full MPLS explanation →

Which TWO statements about MPLS label switching are correct? (Choose two.)

Trap 1: The CE receives a frame with an MPLS label.

CE receives an IP packet without label (unless configured for MPLS).

Trap 2: PHP (Penultimate Hop Popping) causes the egress router to pop the…

PHP causes the penultimate hop to pop the label, not the egress.

Trap 3: The egress LSR performs label swapping before forwarding.

Egress pops the label, not swap.

Study all MPLS and Segment Routing common traps →

A
The transit LSR performs label swapping.
Correct: Transit routers swap the incoming label with an outgoing label.
B
The CE receives a frame with an MPLS label.
Why wrong: CE receives an IP packet without label (unless configured for MPLS).
C
The ingress LSR imposes a label on the packet.
Correct: Ingress does label imposition (push).
D
PHP (Penultimate Hop Popping) causes the egress router to pop the label.
Why wrong: PHP causes the penultimate hop to pop the label, not the egress.
E
The egress LSR performs label swapping before forwarding.
Why wrong: Egress pops the label, not swap.

Full breakdown with real-world context →

Question 7hardmulti select

Read the full MPLS explanation →

Which THREE of the following are benefits of using Segment Routing over LDP in an MPLS network? (Choose three.)

Trap 1: Provides inherent security against label spoofing.

SR does not add security features.

Trap 2: Requires BGP-LU for label distribution.

SR uses IGP for label distribution; BGP-LU is optional.

Study all MPLS and Segment Routing common traps →

A
Enables traffic engineering without RSVP-TE.
Correct: SR-TE provides traffic engineering capabilities.
B
Reduces the number of protocols required in the network.
Correct: Fewer protocols to configure and troubleshoot.
C
Eliminates the need for LDP and RSVP-TE in the core.
Correct: SR uses IGP extensions instead of LDP and RSVP-TE.
D
Provides inherent security against label spoofing.
Why wrong: SR does not add security features.
E
Requires BGP-LU for label distribution.
Why wrong: SR uses IGP for label distribution; BGP-LU is optional.

Full breakdown with real-world context →

Question 8hardmultiple choice

Read the full MPLS explanation →

Refer to the exhibit. A PE router in an MPLS L3VPN network shows the above output. The VRF CUSTOMER contains two routes. Which statement about forwarding for these routes is true?

Exhibit

Refer to the exhibit.

PE1# show mpls forwarding-table
Local  Outgoing    Prefix            Labels Label    Next Hop
16     Pop         10.1.1.0/24        
       No Label    10.2.2.0/24        

PE1# show ip bgp vpnv4 vrf CUSTOMER
Network          Next Hop      Metric LocPrf Weight Path
Route Distinguisher: 100:1
10.1.1.0/24      192.168.1.1          0    100      0 65001 i
10.2.2.0/24      192.168.2.2          0    100      0 65002 i

Trap 1: Both routes are reachable via MPLS.

10.2.2.0/24 has no label, so it is not reachable via MPLS.

Trap 2: Traffic to 10.2.2.0/24 will be forwarded using the BGP next hop…

The BGP next hop (192.168.2.2) does not have a label in the LFIB, so no label is available.

Trap 3: Traffic to 10.2.2.0/24 will be forwarded using IP routing.

'No Label' indicates no label is available; the router will drop the packet because it cannot forward in MPLS core without a label.

Study all MPLS and Segment Routing common traps →

A
Both routes are reachable via MPLS.
Why wrong: 10.2.2.0/24 has no label, so it is not reachable via MPLS.
B
Traffic to 10.1.1.0/24 will be label-switched with an implicit null label.
'Pop' means implicit-null label (label 3), which is popped by the penultimate hop.
C
Traffic to 10.2.2.0/24 will be forwarded using the BGP next hop label.
Why wrong: The BGP next hop (192.168.2.2) does not have a label in the LFIB, so no label is available.
D
Traffic to 10.2.2.0/24 will be forwarded using IP routing.
Why wrong: 'No Label' indicates no label is available; the router will drop the packet because it cannot forward in MPLS core without a label.

Full breakdown with real-world context →

Question 9mediummultiple choice

Read the full MPLS explanation →

Refer to the exhibit. An engineer configured Segment Routing on a router. However, the router does not advertise a Prefix-SID for the loopback0 interface. What is the most likely reason?

Exhibit

Refer to the exhibit.

interface GigabitEthernet0/0
 ip address 10.1.1.1 255.255.255.252
 mpls ip
 segment-routing mpls
!
router ospf 1
 segment-routing mpls
 prefix-sid index 100
 network 10.0.0.0 0.255.255.255 area 0
!
interface Loopback0
 ip address 192.168.1.1 255.255.255.255
 ip ospf 1 area 0
!

Trap 1: The loopback is not included in any OSPF network statement.

The loopback is enabled under OSPF via 'ip ospf 1 area 0'.

Trap 2: The 'segment-routing mpls' command is missing under the loopback…

The loopback does not need 'segment-routing mpls' under it; SR is enabled globally and under the OSPF process.

Trap 3: The 'mpls ip' command is missing on the loopback interface.

'mpls ip' is not required on loopback for SR; it's for LDP.

Study all MPLS and Segment Routing common traps →

A
The loopback is not included in any OSPF network statement.
Why wrong: The loopback is enabled under OSPF via 'ip ospf 1 area 0'.
B
The 'prefix-sid index' command is not associated with the loopback prefix; it should be configured under the OSPF process for that specific prefix.
The prefix-sid index under OSPF is generic; it needs to be tied to the specific prefix, e.g., 'prefix-sid index 100 192.168.1.1/32'.
C
The 'segment-routing mpls' command is missing under the loopback interface.
Why wrong: The loopback does not need 'segment-routing mpls' under it; SR is enabled globally and under the OSPF process.
D
The 'mpls ip' command is missing on the loopback interface.
Why wrong: 'mpls ip' is not required on loopback for SR; it's for LDP.

Full breakdown with real-world context →

Question 10mediummultiple choice

Review the full OSPF breakdown →

A service provider is deploying MPLS L3VPN and notices that BGP next-hop resolution for VPNv4 routes fails on the PE routers. The PE routers are running OSPF as the IGP and have loopback interfaces used for LDP and BGP peering. Which configuration change should the engineer implement to ensure that the BGP next-hop is reachable?

Trap 1: Configure 'neighbor x.x.x.x allowas-in 1' under the BGP VRF…

This allows AS path repetition, not next-hop resolution.

Trap 2: Apply the 'neighbor x.x.x.x next-hop-self' command under the BGP…

This command changes the next-hop to the PE but does not address reachability of the original next-hop.

Trap 3: Increase the 'maximum-paths' value under the BGP address-family…

This affects multipath but not reachability.

Study all MPLS and Segment Routing common traps →

A
Configure 'neighbor x.x.x.x update-source loopback0' under the BGP router configuration.
This ensures BGP uses the loopback as the source IP, making the next-hop reachable via IGP.
B
Configure 'neighbor x.x.x.x allowas-in 1' under the BGP VRF configuration.
Why wrong: This allows AS path repetition, not next-hop resolution.
C
Apply the 'neighbor x.x.x.x next-hop-self' command under the BGP VRF configuration.
Why wrong: This command changes the next-hop to the PE but does not address reachability of the original next-hop.
D
Increase the 'maximum-paths' value under the BGP address-family VPNv4.
Why wrong: This affects multipath but not reachability.

Full breakdown with real-world context →

Question 11easymultiple choice

Open the full BGP breakdown →

An engineer is designing an MPLS network and needs to ensure that VPN traffic between two PE routers is label-switched. The PE routers are connected via a P router and have a full mesh of iBGP sessions. Which label distribution method is required for the VPN labels?

Trap 1: Segment Routing

SR can be used for transport but VPN labels are still advertised via BGP.

Trap 2: RSVP-TE

RSVP-TE is for TE tunnels, not for VPN label distribution.

Trap 3: LDP

LDP assigns labels to IGP routes, not VPN prefixes.

Study all MPLS and Segment Routing common traps →

A
Segment Routing
Why wrong: SR can be used for transport but VPN labels are still advertised via BGP.
B
MP-BGP
MP-BGP carries VPNv4 routes with MPLS labels.
C
RSVP-TE
Why wrong: RSVP-TE is for TE tunnels, not for VPN label distribution.
D
LDP
Why wrong: LDP assigns labels to IGP routes, not VPN prefixes.

Full breakdown with real-world context →

Question 12hardmulti select

Read the full MPLS explanation →

A network engineer is troubleshooting an LDP session failure between two directly connected routers. The routers are configured with the 'mpls ldp' command under the interface. The 'show mpls ldp neighbor' command shows no neighbors. Which two additional pieces of information should the engineer verify? (Choose two.)

Trap 1: Verify that TCP port 646 is open on the interface ACL.

LDP uses UDP for discovery and TCP for session; but the question asks for verification steps, and this is too specific; not the first step.

Trap 2: Verify that 'mpls ip' is enabled globally.

The 'mpls ip' command is not needed; 'mpls ldp' under interface is sufficient.

Trap 3: Verify that OSPF is configured on the interface.

LDP does not require OSPF; any IGP works.

Study all MPLS and Segment Routing common traps →

A
Verify that the interface IP addresses are in the same subnet.
LDP hello messages are sent to the all-routers multicast address; mismatched subnets prevent discovery.
B
Verify that TCP port 646 is open on the interface ACL.
Why wrong: LDP uses UDP for discovery and TCP for session; but the question asks for verification steps, and this is too specific; not the first step.
C
Verify that 'mpls ip' is enabled globally.
Why wrong: The 'mpls ip' command is not needed; 'mpls ldp' under interface is sufficient.
D
Verify that the LDP router IDs are reachable via routing.
LDP uses TCP to establish session; the transport address must be reachable.
E
Verify that OSPF is configured on the interface.
Why wrong: LDP does not require OSPF; any IGP works.

Full breakdown with real-world context →

Question 13mediummultiple choice

Read the full MPLS explanation →

Refer to the exhibit. A network engineer notices that the local label 19 for prefix 10.4.4.0/24 shows 'Untagged' in the outgoing label column. What is the most likely cause?

Exhibit

Refer to the exhibit.

PE1# show mpls forwarding-table
Local  Outgoing    Prefix           Bytes Label   Outgoing   Next Hop
Label  Label       or Tunnel Id     Switched      interface
16     Pop Label   10.1.1.0/24      0             Gi0/0/0    192.168.1.1
17     18          10.2.2.0/24      0             Gi0/0/1    192.168.2.2
18     19          10.3.3.0/24      0             Gi0/0/1    192.168.2.2
19     Untagged    10.4.4.0/24      0             Gi0/0/2    192.168.3.3

Trap 1: The next-hop router 192.168.3.3 is unreachable.

If unreachable, the entry would not be in the LFIB.

Trap 2: Penultimate Hop Popping is enabled on the next-hop router.

PHP would show 'Pop Label', not 'Untagged'.

Trap 3: The MTU on interface Gi0/0/2 is too small.

MTU does not affect label assignment.

Study all MPLS and Segment Routing common traps →

A
The next-hop router 192.168.3.3 is unreachable.
Why wrong: If unreachable, the entry would not be in the LFIB.
B
Penultimate Hop Popping is enabled on the next-hop router.
Why wrong: PHP would show 'Pop Label', not 'Untagged'.
C
The MTU on interface Gi0/0/2 is too small.
Why wrong: MTU does not affect label assignment.
D
LDP is not enabled on the interface toward 192.168.3.3.
If LDP is not enabled, no label is received from the next-hop, resulting in 'Untagged'.

Full breakdown with real-world context →

Question 14mediummulti select

Read the full MPLS explanation →

Which TWO are benefits of using Segment Routing (SR) over traditional LDP-based MPLS?

Trap 1: Requires only OSPF as the IGP.

SR works with both OSPF and IS-IS.

Trap 2: Reduces label imposition at the ingress PE.

SR may increase label stack depth.

Trap 3: Faster convergence due to BGP PIC.

BGP PIC is not exclusive to SR; SR uses IGP convergence.

Study all MPLS and Segment Routing common traps →

A
Eliminates the need for LDP and RSVP-TE protocols.
SR uses IGP to distribute labels, removing LDP and RSVP-TE.
B
Requires only OSPF as the IGP.
Why wrong: SR works with both OSPF and IS-IS.
C
Reduces label imposition at the ingress PE.
Why wrong: SR may increase label stack depth.
D
Faster convergence due to BGP PIC.
Why wrong: BGP PIC is not exclusive to SR; SR uses IGP convergence.
E
Supports traffic engineering without RSVP-TE.
SR-TE uses segment lists for explicit paths.

Full breakdown with real-world context →

Question 15hardmultiple choice

Open the full BGP breakdown →

A service provider has a network with PE1, P1, P2, and PE2 connected in a chain: PE1-P1-P2-PE2. The IGP is IS-IS with wide metrics, and MPLS LDP is enabled on all interfaces. The goal is to provide L3VPN services between PE1 and PE2. The engineer has configured MP-iBGP between PE1 and PE2, and the VPNv4 routes are exchanged. However, when a CE router behind PE1 tries to reach the CE behind PE2, the traffic fails. The engineer checks the MPLS forwarding table on PE1 and sees that the label for the BGP next-hop (PE2's loopback) is 'Untagged'. The BGP next-hop is reachable via ICMP. What is the most likely cause of this issue?

Trap 1: The IS-IS metric between PE1 and P1 is too high, causing suboptimal…

High metric might affect path, but not label assignment.

Trap 2: The MPLS TTL propagation is disabled, causing packets to be dropped.

TTL propagation does not affect label binding.

Trap 3: The MTU on the link between PE1 and P1 is set to 1500, causing…

Fragmentation does not cause 'Untagged'.

Study all MPLS and Segment Routing common traps →

A
The IS-IS metric between PE1 and P1 is too high, causing suboptimal routing.
Why wrong: High metric might affect path, but not label assignment.
B
The MPLS TTL propagation is disabled, causing packets to be dropped.
Why wrong: TTL propagation does not affect label binding.
C
LDP is not enabled on the interface between PE1 and P1.
Without LDP, no label is received from P1 for the BGP next-hop.
D
The MTU on the link between PE1 and P1 is set to 1500, causing fragmentation.
Why wrong: Fragmentation does not cause 'Untagged'.

Full breakdown with real-world context →

Question 16easymultiple choice

Read the full MPLS explanation →

A network operator is migrating from traditional MPLS LDP to Segment Routing (SR) with IS-IS. The network consists of four routers (R1-R4) in a square topology. The engineer has enabled SR on all routers and configured prefix-SIDs for loopbacks. However, when checking the MPLS forwarding table on R1, the engineer sees that some prefixes have label values that are not the prefix-SIDs. For example, the prefix for R4's loopback shows label 16004 instead of the expected 16004 (which is correct). But for another prefix, the label is 16003 instead of 16003 (correct). The engineer does not see any labels for some external routes. What is the most likely reason that some labels are missing?

Trap 1: The IS-IS wide metrics are not enabled on all interfaces.

Wide metrics are needed for SR but not the cause of missing labels.

Trap 2: Route redistribution from another protocol is not configured.

Redistribution does not automatically assign labels.

Trap 3: The prefix-SIDs are inconsistent across routers.

The engineer saw correct SIDs for some prefixes.

Study all MPLS and Segment Routing common traps →

A
The IS-IS wide metrics are not enabled on all interfaces.
Why wrong: Wide metrics are needed for SR but not the cause of missing labels.
B
Route redistribution from another protocol is not configured.
Why wrong: Redistribution does not automatically assign labels.
C
The prefix-SIDs are inconsistent across routers.
Why wrong: The engineer saw correct SIDs for some prefixes.
D
External routes are not covered by prefix-SIDs; they require LDP or another label distribution mechanism.
SR only assigns labels to IGP prefixes; external routes need separate handling.

Full breakdown with real-world context →

Question 17mediummultiple choice

Read the full MPLS explanation →

A service provider is deploying MPLS-TE with RSVP-TE in their core network. They notice that some LSPs are not being established due to resource contention. Which action would best address this issue without redesigning the entire traffic engineering deployment?

Trap 1: Increase the bandwidth of all core links.

While increasing bandwidth may alleviate congestion, it does not address the root cause of resource contention and is a costly redesign.

Trap 2: Configure LSP path-option explicit paths with strict hops.

Strict explicit paths may avoid certain links but do not solve resource contention; they may even worsen it by restricting path choices.

Trap 3: Disable RSVP-TE and use LDP for label distribution.

Disabling RSVP-TE removes traffic engineering capabilities, which is not a solution to contention.

Study all MPLS and Segment Routing common traps →

A
Enable preemption on RSVP-TE LSPs with appropriate priority levels.
Preemption allows higher-priority LSPs to take resources from lower-priority ones, resolving contention dynamically.
B
Increase the bandwidth of all core links.
Why wrong: While increasing bandwidth may alleviate congestion, it does not address the root cause of resource contention and is a costly redesign.
C
Configure LSP path-option explicit paths with strict hops.
Why wrong: Strict explicit paths may avoid certain links but do not solve resource contention; they may even worsen it by restricting path choices.
D
Disable RSVP-TE and use LDP for label distribution.
Why wrong: Disabling RSVP-TE removes traffic engineering capabilities, which is not a solution to contention.

Full breakdown with real-world context →

Question 18hardmultiple choice

Open the full BGP breakdown →

Refer to the exhibit. An engineer is configuring Segment Routing for BGP (BGP-SR) on a PE router to assign labels to prefixes learned from a CE. The route-policy SET-LABEL is applied to the neighbor under the address-family ipv4 unicast. However, the CE prefix 10.1.1.0/24 is not receiving the label. What is the most likely reason?

Exhibit

Refer to the exhibit.

router bgp 65000
 neighbor 10.0.0.1 remote-as 65001
 neighbor 10.0.0.1 update-source Loopback0
 !
 address-family vpnv4
  neighbor 10.0.0.1 activate
  neighbor 10.0.0.1 send-community extended
 exit-address-family
!
route-policy SET-LABEL
  if destination in (10.1.1.0/24) then
    set label-index 100
  endif
 end-policy

Trap 1: The route-policy syntax is incorrect; 'destination' should be 'ip…

The 'destination' condition in route-policy is valid and can match a prefix directly.

Trap 2: The update-source should be the interface facing the CE, not…

The update-source Loopback0 is appropriate for BGP sessions between PEs, but for a CE-facing session, the direct interface should be used; however, this would not prevent label assignment, only session establishment.

Trap 3: The 'set label-index' command should be 'set label' for BGP-SR.

In BGP-SR, 'set label-index' is the correct command to assign a label index for a prefix-SID.

Study all MPLS and Segment Routing common traps →

A
The route-policy syntax is incorrect; 'destination' should be 'ip prefix-list'.
Why wrong: The 'destination' condition in route-policy is valid and can match a prefix directly.
B
The update-source should be the interface facing the CE, not Loopback0.
Why wrong: The update-source Loopback0 is appropriate for BGP sessions between PEs, but for a CE-facing session, the direct interface should be used; however, this would not prevent label assignment, only session establishment.
C
The neighbor is missing 'send-community extended' under address-family ipv4 unicast.
BGP-SR uses the prefix-SID attribute carried in extended communities; without this, labels are not advertised.
D
The 'set label-index' command should be 'set label' for BGP-SR.
Why wrong: In BGP-SR, 'set label-index' is the correct command to assign a label index for a prefix-SID.

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Question 19easymultiple choice

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A service provider is designing a greenfield MPLS core and wants to minimize control-plane complexity while still supporting traffic engineering. They plan to use Segment Routing with MPLS. Which statement about Segment Routing in this context is accurate?

Trap 1: Segment Routing only works with IPv6 data plane.

Segment Routing can operate with both MPLS and IPv6 data planes; SR-MPLS uses MPLS encapsulation.

Trap 2: Segment Routing uses RSVP-TE for label distribution.

Segment Routing relies on IGP to distribute segment IDs, not RSVP-TE.

Trap 3: Segment Routing requires TI-LFA to be enabled for traffic…

TI-LFA is a fast-reroute mechanism that can be used with SR but is not a requirement for traffic engineering.

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A
Segment Routing only works with IPv6 data plane.
Why wrong: Segment Routing can operate with both MPLS and IPv6 data planes; SR-MPLS uses MPLS encapsulation.
B
Segment Routing uses RSVP-TE for label distribution.
Why wrong: Segment Routing relies on IGP to distribute segment IDs, not RSVP-TE.
C
Segment Routing reduces the number of protocols required in the core.
SR eliminates LDP and RSVP-TE, relying only on an IGP with SR extensions, thus reducing protocol complexity.
D
Segment Routing requires TI-LFA to be enabled for traffic engineering.
Why wrong: TI-LFA is a fast-reroute mechanism that can be used with SR but is not a requirement for traffic engineering.

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Question 20mediumdrag order

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Drag and drop the steps for the BGP route selection process (best path selection) in order.

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps

Order

1Step 1

2Step 2

3Step 3

4Step 4

5Step 5

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Frequently asked questions

What does the 350-501 exam test about MPLS and Segment Routing?: Routing questions usually test route selection (administrative distance, metric), how static routes are configured and when they are preferred over dynamic routing.
How should I use these practice questions?: Select your answer before revealing the explanation. Then read why each option is right or wrong — this active recall approach builds retention far faster than re-reading notes.
Can I practise just MPLS and Segment Routing questions in a focused session?: Yes — the session launcher on this page draws every question from the MPLS and Segment Routing domain. Use a 10-question session first to gauge your baseline, then move to 20 or 30 once the weak spots are clear.
Where can I practise other 350-501 topics?: Use the topic links above to move to related areas, or go back to the 350-501 question bank to see all topics.
Are these real exam questions or dumps?: These are original practice questions written to test the same concepts the 350-501 exam covers. They are not copied from any real exam or dump site.

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All 350-501 questions MPLS and Segment Routing domain overview 350-501 exam guide

Exam traps to avoid

▸Lower administrative distance wins when two routing sources have the same prefix.
▸A static route with an exit interface creates a directly-connected dependency.
▸The gateway of last resort is set by the default route, not automatically.
▸Metric is only compared within the same routing protocol.

MPLS and Segment Routing practice questions

What to know about MPLS and Segment Routing

Common MPLS and Segment Routing exam traps

MPLS and Segment Routing questions

A service provider is designing a new MPLS core network using Segment Routing with MPLS data plane. They require traffic engineering capabilities to optimize bandwidth utilization. Which technology should be used to compute optimal paths based on IGP link attributes and bandwidth constraints?

An engineer is deploying MPLS in the core and wants to ensure that all core routers use the same label for a specific prefix, regardless of which router originated it. Which MPLS label allocation mode should be used?

During an MPLS network migration from LDP to Segment Routing, an engineer notices that some routers are not advertising Prefix-SIDs for certain loopbacks. The IGP is OSPF. What configuration is required on these routers to advertise Prefix-SIDs?

A service provider is deploying a new MPLS core with Segment Routing and requires fast convergence upon link failure. They plan to use TI-LFA (Topology Independent Loop-Free Alternate). What is a prerequisite for TI-LFA to provide protection against any single link failure?

Which TWO statements about MPLS label switching are correct? (Choose two.)

Which THREE of the following are benefits of using Segment Routing over LDP in an MPLS network? (Choose three.)

Refer to the exhibit. A PE router in an MPLS L3VPN network shows the above output. The VRF CUSTOMER contains two routes. Which statement about forwarding for these routes is true?

Exhibit

Refer to the exhibit. An engineer configured Segment Routing on a router. However, the router does not advertise a Prefix-SID for the loopback0 interface. What is the most likely reason?

Exhibit

An engineer is designing an MPLS network and needs to ensure that VPN traffic between two PE routers is label-switched. The PE routers are connected via a P router and have a full mesh of iBGP sessions. Which label distribution method is required for the VPN labels?

Refer to the exhibit. A network engineer notices that the local label 19 for prefix 10.4.4.0/24 shows 'Untagged' in the outgoing label column. What is the most likely cause?

Exhibit

Which TWO are benefits of using Segment Routing (SR) over traditional LDP-based MPLS?

A service provider is deploying MPLS-TE with RSVP-TE in their core network. They notice that some LSPs are not being established due to resource contention. Which action would best address this issue without redesigning the entire traffic engineering deployment?

Exhibit

A service provider is designing a greenfield MPLS core and wants to minimize control-plane complexity while still supporting traffic engineering. They plan to use Segment Routing with MPLS. Which statement about Segment Routing in this context is accurate?

Drag and drop the steps for the BGP route selection process (best path selection) in order.

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