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350-501 · domain

MPLS and Segment Routing

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.

193 questions46 easy90 medium57 hard

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What this domain covers

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.

Question index

All MPLS and Segment Routing questions (193)

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1

An engineer is configuring MPLS LDP on a Cisco router. Which TWO statements about LDP operation are correct? (Choose two.)

Easy
2

A service provider is migrating from LDP-based MPLS to Segment Routing (SR-MPLS) with IS-IS. After enabling SR on all routers, the adjacency segment IDs (ADJ-SIDs) are not being advertised. Which configuration is missing?

Hard
3

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

Hard
4

In SRv6, which endpoint behavior is used for decapsulation and forwarding to a Layer 3 VPN IPv4 destination, removing the outer IPv6 header?

Hard
5

An engineer is configuring EVPN IRB (Integrated Routing and Bridging) to provide IP connectivity between tenants across a service provider network. Which THREE components are essential for EVPN IRB operation? (Choose three.)

Medium
6

Which tool can verify connectivity along an MPLS Label Switched Path (LSP) and detect label loops?

Easy
7

In SR-MPLS traffic engineering, which three components are essential for configuring an SR Policy on a headend router? (Choose three.)

Hard
8

A company is connecting two sites using MPLS L3VPN. The PE routers are running both LDP and Segment Routing (SR-MPLS) in the core. The CE router at Site A cannot reach the CE at Site B. On the PEs, the VRF routes are present. Which command would you use to verify the MPLS forwarding path for the VPN traffic?

Medium
9

In CSPF (Constrained Shortest Path First) for MPLS-TE, which of the following is NOT a typical constraint considered during path computation?

Hard
10

A network engineer is configuring an MPLS L3VPN on a PE router. The VRF is configured with route-target import/export. The PE and CE are running eBGP. The CE advertises routes to the PE, and the PE installs them in the VRF routing table. However, the remote PE does not receive these routes via BGP VPNv4. The local PE's BGP table shows the VPNv4 prefixes with the correct next hop and label. The remote PE's BGP table shows no such prefixes. The IGP between the PEs is working, and MPLS LSPs are up. What is the most likely cause and correct action?

Medium
11

An SRv6 SID is composed of three parts: Locator, Function, and Arguments. Which part identifies the SRv6-capable node in the network?

Medium
12

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?

Hard
13

Which two are benefits of using EVPN-VPWS over traditional VPWS? (Choose two.)

Hard
14

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

Medium
15

A service provider is migrating from LDP to SR-MPLS. Which mechanism allows a router to allocate labels for prefixes using both LDP and SR simultaneously during the migration?

Hard
16

In an MPLS network using LDP, which statement correctly describes the label distribution behavior for a given FEC?

Medium
17

In SR-MPLS TE, a headend router is configured with an SR Policy that includes an explicit candidate path with segment list [16001, 16003]. What do these numbers represent?

Medium
18

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?

Easy
19

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?

Medium
20

Refer to the exhibit. The output shows an MPLS forwarding entry with FRR protection. What is the purpose of the backup path shown?

Hard
21

In an MPLS-TE tunnel configuration, which RSVP message carries the Explicit Route Object (ERO) that specifies the explicit path the tunnel must follow?

Medium
22

Which of the following best describes the function of CSPF in MPLS-TE?

Medium
23

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?

Easy
24

Match each IS-IS term to its definition.

Medium
25

An SP network uses RSVP-TE for MPLS traffic engineering with FRR link protection. Which THREE statements are correct about RSVP-TE operation and FRR? (Choose three.)

Hard
26

Which EVPN component ensures that only one of the multi-homed PEs forwards traffic to the CE for a given Ethernet segment?

Hard
27

In SR-TE, a headend router is configured with an SR Policy that includes an explicit candidate path with segment list [16001, 16003, 16005]. What does this segment list represent?

Hard
28

What is the primary purpose of the SRGB (Segment Routing Global Block) when configuring SR-MPLS on a network?

Medium
29

Which THREE are mechanisms used in EVPN to support multi-homing and load balancing? (Choose three.)

Hard
30

An engineer is troubleshooting MPLS label switching in a service provider core. They notice that packets are being forwarded correctly between provider edge routers, but when they check the MPLS forwarding table on a P router, they see only implicit-null labels for some destinations. What is the most likely reason for this?

Medium
31

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?

Medium
32

An engineer is troubleshooting an MPLS-TE tunnel that is not coming up. The configuration includes an explicit path with strict hops. Which TWO conditions could prevent the tunnel from being established? (Choose two.)

Medium
33

Which TWO are characteristics of SR-MPLS when compared to LDP-based MPLS? (Choose two.)

Medium
34

Which component in EVPN is used to uniquely identify an Ethernet segment across multiple PE devices in a multi-homing scenario?

Easy
35

Based on the exhibit, which prefix is missing a label binding and likely causing traffic to be dropped?

Medium
36

Which three are characteristics of SR-TE policies? (Choose three.)

Medium
37

An engineer configures an MPLS-TE tunnel with a bandwidth of 100 Mbps and an explicit path that avoids a specific link. Which RSVP message carries the Explicit Route Object (ERO) to signal the path?

Medium
38

A network engineer notices that BGP-LU prefixes learned from an eBGP neighbor are not being installed in the MPLS forwarding table (LFIB). The BGP table shows the prefixes with the correct label. The IGP route to the neighbor is reachable. What additional configuration is needed?

Hard
39

In MPLS, which operation occurs when a router receives a labeled packet and replaces the top label with a new label before forwarding?

Easy
40

In SRv6, which behavior is used for L3VPN decapsulation (removing the outer IPv6 header and SRH, and forwarding the inner IPv4 packet based on the VPN routing table)?

Hard
41

A network architect is designing an MPLS network that must provide fast convergence in case of a link failure. The network uses Segment Routing. Which mechanism provides sub-50ms protection by using a precomputed backup path?

Easy
42

In SR-TE, a headend router is configured with an SR Policy using an explicit candidate path that includes a segment list [100, 200, 300]. If all routers have the same SRGB starting at 10000, what is the actual outgoing label stack for the first segment?

Hard
43

In Segment Routing (SR-MPLS), which IGP TLV is used by IS-IS to advertise the Node SID for a prefix?

Medium
44

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

Medium
45

An engineer is deploying MPLS-TE with FRR using the 1:1 detour method. Which statement about link protection in this scenario is true?

Hard
46

A network engineer is troubleshooting MPLS L3VPN issues on a PE router. The CE router is receiving routes from the PE, but the CE cannot ping the remote CE. The PE shows the remote prefix in its routing table and in the VRF. What is the most likely cause?

Medium
47

In MPLS, which operation is performed when a packet arrives at a transit router and the top label matches the router's own label assigned for the FEC?

Easy
48

An engineer wants to configure SR-TE without using RSVP. Which mechanism does SR-TE use to specify the explicit path?

Medium
49

Which RSVP-TE message is used to reserve resources along the path and includes the Explicit Route Object (ERO)?

Medium
50

A service provider is implementing Segment Routing over IPv6 (SRv6) in their core. They want to provide path isolation for different services using SRv6 SIDs. Which SID structure is used to encode both the locator and the function?

Hard
51

Which LDP mode uses downstream unsolicited label distribution and liberal label retention?

Easy
52

Which SRv6 endpoint behavior is used for L3VPN decapsulation and IP forwarding to the destination in a VRF?

Medium
53

In an MPLS network using LDP, which LDP mode allocates a label for every prefix in the routing table and advertises it to all LDP neighbors, regardless of whether the neighbor requests it?

Medium
54

An engineer is configuring an MPLS Traffic Engineering tunnel using RSVP-TE. The tunnel is intended to carry voice traffic with strict delay requirements. Which RSVP-TE object should be used to enforce a maximum delay path?

Easy
55

In Segment Routing over IPv6 (SRv6), what is the function of the 'Locator' part of an SRv6 SID?

Easy
56

Which TWO statements correctly describe RSVP-TE reservation styles? (Choose two.)

Medium
57

A service provider is designing a new MPLS core network and wants to simplify traffic engineering without deploying a centralized controller. Which technology should be used to enable source-routed paths with explicit path control?

Easy
58

Match each Ethernet OAM protocol to its function.

Medium
59

Which component of SRv6 SID format is used to identify the specific function (e.g., End, End.X) on the node?

Medium
60

An SR-TE policy is configured with a candidate path containing multiple segment lists. Which selection criteria is used to choose the active segment list among the candidate paths?

Medium
61

Which protocol is typically used to distribute MPLS labels between directly connected LSRs?

Easy
62

An engineer is configuring MPLS-TE FRR for link protection. Which of the following options describes a 1:1 protection scheme where a dedicated detour LSP is created for each protected LSP?

Hard
63

Which component of an MPLS-TE FRR (Fast Reroute) configuration provides protection for the next-hop node by bypassing it?

Easy
64

Which LDP label retention mode stores all received label bindings even if they are not currently used for forwarding?

Easy
65

An MPLS TE tunnel is configured with an explicit path. Which RSVP message is used by the headend to signal the path and carry the Explicit Route Object (ERO) listing the hops?

Medium
66

Which SR-MPLS SID is advertised by an IS-IS router to identify a specific link and is distributed only to adjacent neighbors?

Medium
67

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?

Hard
68

Refer to the exhibit. An operator configures an SR-TE policy on a headend router. Which statement is true about the traffic steered into this policy?

Hard
69

Which two statements about MPLS label operations are true? (Choose two.)

Easy
70

In RSVP-TE, which filter spec style allows multiple senders to share the same reserved resources on a link, as long as their flows do not exceed the reservation?

Hard
71

When deploying EVPN with SR-MPLS or SRv6, which THREE statements about EVPN multi-homing and related concepts are correct? (Choose three.)

Hard
72

An engineer is designing an EVPN IRB (Integrated Routing and Bridging) solution. Which two statements about EVPN IRB are correct? (Choose two.)

Medium
73

Refer to the exhibit. The show command output displays the LDP neighbor state. What does the 'Downstream' label mode indicate about label distribution?

Easy
74

An engineer configures an SR-TE policy with a segment list containing adjacency SIDs. The required path includes a strict loose hop through a specific router. Which segment type should be used for the strict hop?

Hard
75

Which TWO statements about SR-MPLS compared to LDP are correct? (Choose two.)

Medium
76

In an MPLS L3VPN network with route reflectors, what is the default behavior regarding the BGP next-hop attribute for reflected VPNv4 routes?

Hard
77

Which four statements correctly describe the SRv6 micro-SID (uSID) concept? (Choose four.)

Hard
78

In MPLS, what is the term for the operation where the top label is removed and replaced with a new label?

Easy
79

An engineer configures an RSVP-TE tunnel with a bandwidth of 100 Mbps and an explicit path that excludes a specific interface. The tunnel fails to come up. Which term describes the path computation method used by RSVP-TE to find a feasible path given these constraints?

Hard
80

An engineer is troubleshooting an MPLS network where some routers are not exchanging labels via LDP. Which two steps are most appropriate for diagnosing the issue? (Choose two.)

Medium
81

Refer to the exhibit. A network engineer is configuring a segment routing traffic engineering policy. The output shows two candidate paths. Why is path1 selected as the active path even though path2 has a bandwidth constraint?

Medium
82

Which THREE functions are provided by EVPN multi-homing? (Choose three.)

Hard
83

An operator is deploying EVPN-VPWS over an MPLS network. Which component uniquely identifies a multihomed Ethernet segment in EVPN?

Hard
84

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?

Easy
85

In EVPN with SRv6, which SID behavior is used for integrated routing and bridging (IRB) to forward packets between the IP fabric and the Ethernet segment?

Hard
86

In SR-MPLS, what is the purpose of the SRGB (Segment Routing Global Block)?

Medium
87

Which two statements about LDP liberal label retention are true? (Choose two.)

Medium
88

An engineer is configuring MPLS LDP on a Cisco router. The router uses downstream unsolicited mode with liberal label retention. Which behavior describes the label distribution and retention on this router?

Medium
89

What does the output indicate about the TI-LFA protection on R1?

Hard
90

Which MPLS label operation is performed by the penultimate hop router in PHP (Penultimate Hop Popping)?

Easy
91

Which three are required components for deploying Segment Routing in an MPLS network? (Choose three.)

Medium
92

Refer to the exhibit. An engineer notices that R1 has an LDP neighbor but 'show mpls forwarding-table' on R1 shows no label bindings for prefixes learned from R2. What is the most likely cause?

Medium
93

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?

Hard
94

The CE router behind the VRF interface is unable to reach the remote CE. Which configuration error is most likely the cause?

Medium
95

Which two are characteristics of the Anycast SID in Segment Routing? (Choose two.)

Hard
96

In SRv6, which Segment Identifier (SID) format is used to encode a function that performs IPv6 decapsulation and forwarding?

Easy
97

An engineer is troubleshooting an MPLS VPN issue where CE1 cannot ping CE2 across the provider network. The PE routers are configured with MP-BGP and LDP. On PE1, 'show ip bgp vpnv4 vrf CUST' shows the route to CE2's loopback as valid, but 'show mpls forwarding-table' does not list a label for that prefix. What is the most likely cause?

Hard
98

A network operator is configuring RSVP-TE tunnels for traffic engineering in an MPLS core. They want to enforce that the tunnel path strictly follows a predefined set of hops. Which explicit path option should be used?

Medium
99

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

Medium
100

An engineer is implementing MPLS-TE Fast Reroute for link protection. Which protection method provides a backup tunnel that bypasses a specific link, protecting all LSPs traversing that link?

Medium
101

In EVPN with Integrated Routing and Bridging (IRB), which type of interface is used to connect the bridge domain to the IP-VRF for inter-subnet forwarding?

Hard
102

Which label distribution mode does LDP use by default in Cisco IOS?

Easy
103

An SP network engineer is designing a new segment routing traffic engineering deployment within a single IGP area. The network consists of 50 core routers running IS-IS and MPLS. The engineer needs to steer traffic from Router A to Router D over a path that avoids high latency links. Which technology should be used to define and instantiate the explicit path?

Easy
104

Which THREE are valid SRv6 endpoint behaviors for VPN services? (Choose three.)

Hard
105

What is the default range of the Segment Routing Global Block (SRGB) on Cisco IOS XR?

Easy
106

In MPLS, which forwarding table is used to determine the outgoing label and interface for a labeled packet?

Easy
107

In MPLS, which label operation is performed by a Penultimate Hop Popping (PHP) router?

Medium
108

Which two statements about MPLS label distribution are correct? (Choose two)

Medium
109

Which label distribution protocol is replaced by segment routing in SR-MPLS deployments?

Easy
110

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

Medium
111

Which THREE steps are required when configuring MPLS L3VPN on a PE router? (Choose three.)

Medium
112

An engineer is configuring SR-MPLS in an IS-IS network. Which IS-IS TLV is used to advertise the Segment Routing Global Block (SRGB) and Node-SID assignments?

Medium
113

In SR-MPLS, which mechanism replaces LDP for label distribution?

Easy
114

In MPLS-TE, what is the purpose of the Explicit Route Object (ERO) in the RSVP PATH message?

Easy
115

A network engineer is designing an MPLS core using Segment Routing. They want to minimize label stack depth while still providing fast convergence using TI-LFA. Which prefix-SID assignment strategy should be used?

Easy
116

Which label operation is performed on a router when an MPLS packet arrives with a top label that matches a local label assigned to a directly connected prefix?

Easy
117

In SRv6 micro-SID (uSID) compression, which part of the SID is used to carry a compressed instruction set, enabling efficient forwarding with a shorter SID list?

Hard
118

In an MPLS L3VPN network, a customer has overlapping IP addresses between two VPNs. The provider edge routers are configured with VRF instances. Which method ensures that traffic from one VPN does not leak into the other when using MPLS labels?

Hard
119

Which BGP extended community is used to signal the OSPF domain ID between PE routers in an MPLS L3VPN when OSPF is the PE-CE protocol?

Medium
120

Refer to the exhibit. An engineer is troubleshooting packet loss in the MPLS core. For prefix 10.3.3.0/24, the outgoing label is 'Untagged'. What does this indicate?

Medium
121

A network operator is deploying Segment Routing with TI-LFA across an OSPF network. After configuring OSPF with 'segment-routing mpls' and 'fast-reroute per-prefix', they notice that backup paths are not being installed for some prefixes. 'Show ip ospf segment-routing protected' shows 'No FRR backup' for those prefixes. What is a possible reason?

Hard
122

A service provider is migrating from a legacy MPLS network using LDP to Segment Routing (SR-MPLS). They have enabled SR on all routers and are using IS-IS. The migration plan is to keep LDP running alongside SR during the transition. After enabling SR, some traffic is being forwarded using the SR path, but the network operator notices that some CEs in an L2VPN are experiencing packet loss during failover scenarios. Troubleshooting shows that the primary pseudowire is using SR labels, but the backup pseudowire is still using LDP labels. The backup path is not working correctly. What is the most likely cause?

Easy
123

An MPLS network is experiencing micro-loops during convergence after a link failure. The network uses LDP and IS-IS as IGP. Which of the following solutions can prevent micro-loops during IGP convergence without requiring additional protocols?

Hard
124

A service provider is deploying MPLS L2VPN using Virtual Private Wire Service (VPWS). After configuration, the two CEs cannot ping each other. The PE routers show the xconnect interface is up, but no MAC addresses are learned. What is the most likely cause?

Medium
125

Which TWO are characteristics of Segment Routing (SR-MPLS)? (Choose two.)

Easy
126

A service provider is migrating from LDP to Segment Routing in its MPLS core. The team has enabled IS-IS as the IGP and configured segment routing under the IS-IS process on all core routers. However, after the migration, some LSPs are not being signaled correctly and traffic is blackholing. Which action should be taken to ensure seamless interworking between LDP and SR during the migration?

Medium
127

Which BGP address family must be used to exchange VPNv4 routes between PE routers in an MPLS L3VPN?

Medium
128

When configuring an MPLS-TE tunnel with affinity/constraint-based routing, what is the effect of assigning a link attribute of 'red' and setting the tunnel's affinity to include 'red' with the 'include-all' keyword?

Medium
129

Which THREE are EVPN multi-homing functions? (Choose three.)

Hard
130

An engineer is configuring MPLS LDP on a Cisco router. The router is using downstream unsolicited mode and liberal label retention. Which statement correctly describes the label advertisement behavior?

Medium
131

Drag and drop the steps to configure a PPPoE client on a Cisco router into the correct order.

Medium
132

In SRv6, which endpoint behavior is used for decapsulating the outer IPv6 header and performing an IPv4 lookup (e.g., for L3VPN)?

Hard
133

In SR-MPLS, which THREE statements correctly describe the properties of Adjacency SIDs? (Choose three.)

Hard
134

In an MPLS L3VPN network, a route reflector (RR) is used to distribute VPNv4 routes between PE routers. After a new PE router (PE4) is added, some VPN routes are not being received by other PEs. Which TWO actions should be investigated to resolve the issue? (Choose two.)

Hard
135

A service provider is transitioning from LDP-based MPLS to Segment Routing (SR-MPLS). Which TWO statements correctly describe differences or interoperability considerations? (Choose two.)

Medium
136

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?

Hard
137

Which TWO statements correctly describe Segment Routing characteristics? (Select two.)

Medium
138

An engineer is configuring RSVP-TE fast reroute for link protection. Which protection method uses a pre-configured bypass tunnel that protects multiple LSPs on the same link?

Medium
139

A service provider is troubleshooting an MPLS L3VPN issue where a CE router is receiving the VPN route from the PE but cannot ping the remote CE's loopback. The PE shows that the VPN label is assigned but cannot route the packets. Which command would help determine if the remote PE is correctly resolving the BGP next-hop via IGP?

Hard
140

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?

Medium
141

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

Medium
142

An MPLS core network uses LDP to distribute labels. An engineer wants to verify that the LDP session between two routers is up and exchanging labels. Which command should be used?

Easy
143

An engineer is troubleshooting MPLS traffic engineering tunnels and needs to verify path calculation and RSVP errors. Which command should be used?

Hard
144

Which THREE are valid methods to provide fast convergence in an MPLS/Segment Routing network? (Select three.)

Hard
145

A service provider is migrating their MPLS core network to Segment Routing (SR-MPLS). All existing core routers run IOS-XR and are configured with an SRGB of 16000-23999 and OSPF as the IGP. A new router (R5) is added as a PE. The engineer configures R5 with the same SRGB and enables segment-routing under OSPF. However, when configuring an SR-TE policy from R5 to the remote loopback 10.0.0.1 on R1, the policy remains down. Show commands reveal that R5 is not learning the prefix-SID for 10.0.0.1. On R1, the prefix-SID is configured with index 100. The engineer verifies that OSPF adjacencies are up and that R5 can ping 10.0.0.1. What is the most likely cause of the issue?

Medium
146

In an MPLS network using RSVP-TE for traffic engineering, which two mechanisms can be used for fast reroute (FRR) protection? (Choose two.)

Medium
147

In MPLS forwarding, what label operation does a transit LSR perform on the top label of a labeled packet?

Easy
148

An engineer notices that MPLS VPN traffic is taking a suboptimal path because the MPLS label binding for the BGP next-hop loopback is missing. What is the most likely cause?

Easy
149

In SR-MPLS, when a router receives a packet with an MPLS label corresponding to an Adjacency SID, what operation does it perform?

Medium
150

In EVPN multi-homing with all-active mode, which mechanism is used to elect a designated forwarder (DF) for broadcast, unknown unicast, and multicast (BUM) traffic on a given Ethernet segment?

Medium
151

A network engineer is designing a Segment Routing over IPv6 (SRv6) deployment. Which TWO statements are true about the SRv6 SID format and behaviors? (Choose two.)

Medium
152

Which LDP label distribution mode is characterized by a router advertising labels for all prefixes in its routing table to all neighbors, regardless of whether they are needed?

Medium
153

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?

Medium
154

Which two actions are performed by an MPLS label edge router (LER) when it receives an unlabeled IP packet destined for a prefix with an LSP? (Choose two.)

Medium
155

Which SRv6 SID behavior is used to support EVPN-IRB (Integrated Routing and Bridging) for L2VPN with bridging?

Hard
156

In SRv6, what is the function of the 'End.DT4' behavior?

Hard
157

Which RSVP message is used to tear down an MPLS-TE LSP by being sent from the ingress toward the egress?

Medium
158

An engineer configures an SRv6 SID with the behavior End.DT6. What is the primary function of this SID?

Medium
159

Which TWO commands are most effective to verify that an SR-TE policy is active and forwarding traffic? (Choose two.)

Hard
160

A service provider is deploying MPLS in their core network and wants to ensure that all routers in the MPLS domain can dynamically exchange label bindings. Which protocol should be enabled on all routers to meet this requirement?

Easy
161

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.)

Hard
162

A service provider is using Segment Routing with TI-LFA for fast convergence. During a link failure, the router performing the local repair must compute a backup path that avoids the failed link. Which type of Adjacency Segment Identifier (Adj-SID) is required for the backup path to be loop-free?

Medium
163

In RSVP-TE, which message is sent by the headend router along the explicit route to reserve resources and establish an LSP?

Medium
164

A service provider has deployed segment routing with OSPF as the IGP in its core network. The network consists of 100 routers in a single area. The operations team reports that after a link failure between Router X and Router Y, traffic from Router A to Router B is taking a suboptimal path even though IGP convergence is complete and all routers have updated their LSDB. Router A and Router B are both segment routing capable. The team verifies that no SR-TE policies are configured and that all routers are using the default SPF algorithm. The expected shortest path from A to B should go through the newly restored link, but instead it still traverses an alternate path. Which action should resolve the issue?

Easy
165

A service provider is migrating from LDP to Segment Routing in an IS-IS network. After enabling IS-IS with segment-routing on all routers, they observe that some prefixes still receive labels from LDP instead of from SR. Which configuration is most likely missing on these routers?

Hard
166

In an EVPN-VPWS (Virtual Private Wire Service) deployment, which identifier is used to uniquely identify an Ethernet Segment for multi-homing?

Medium
167

A service provider wants to use Segment Routing TE with Flex-Algo to engineer traffic around links with low bandwidth. Which configuration approach should be taken?

Hard
168

What is the purpose of the SRGB (Segment Routing Global Block) in SR-MPLS?

Easy
169

A service provider is implementing MPLS in their core network. They want to ensure that labeled packets for BGP prefixes are forwarded correctly without requiring an IGP label for every BGP prefix. Which technique should be used to achieve this?

Medium
170

A network engineer is configuring Segment Routing on an IOS-XR router. They want to use the preferred algorithm for automatically computing paths based on IGP metrics. Which algorithm should be configured under the SR segment list?

Easy
171

In Segment Routing over MPLS (SR-MPLS), how are Prefix-SIDs advertised in IS-IS?

Medium
172

Which two MPLS OAM tools can be used to troubleshoot label switching paths? (Choose two)

Easy
173

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?

Easy
174

Which TWO types of SIDs are defined in Segment Routing? (Select two.)

Easy
175

A network operator is implementing segment routing (SR-MPLS) using OSPF as the IGP. Which OSPF TLV is used to advertise the Node SID (Prefix SID) for a router's loopback address?

Hard
176

In EVPN multi-homing, which two mechanisms are used to avoid duplicate packets and ensure efficient forwarding? (Choose two.)

Medium
177

Refer to the exhibit. The router has three LDP neighbors established. A network administrator notices that MPLS labels for the prefix 10.4.4.0/24 are not being advertised from this router to its neighbors, although the prefix is present in the routing table. Which is the most likely cause?

Medium
178

Which label is used for an Adjacency SID in SR-MPLS?

Easy
179

Which three statements accurately describe the benefits of Segment Routing over RSVP-TE for traffic engineering? (Choose three.)

Hard
180

Which MPLS TE mechanism provides link protection by pre-establishing a backup LSP that bypasses a specific link, activated when the link fails?

Medium
181

During MPLS LDP operation, a router receives a label mapping for a prefix from its neighbor. What is the correct behavior when the receiving router has a route to that prefix?

Easy
182

An engineer is configuring MPLS on a Cisco router. Which label operation is performed on the ingress LSR when a packet enters the MPLS domain?

Easy
183

Which RSVP reservation style is most commonly used in MPLS-TE to allow sharing of resources among multiple LSPs of the same session?

Medium
184

What is the purpose of Constrained Shortest Path First (CSPF) in MPLS-TE?

Medium
185

A large enterprise uses MPLS L3VPN to connect multiple sites. They want to implement inter-AS option B (ASBR-to-ASBR MP-eBGP) for scalability. Which statement about this model is correct?

Medium
186

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?

Medium
187

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?

Medium
188

A service provider is troubleshooting an MPLS L3VPN scenario where a customer in VRF Blue cannot reach a server in VRF Blue at a remote site. The PEs are running MPLS with LDP. The VRF on both PEs shows the remote prefix. The PE at the local site shows the label from the remote PE for the prefix in the BGP table. However, when pinging from the CE, the packets are dropped. A packet capture on the core shows MPLS packets with the correct VPN label, but the transport label is missing. Further investigation shows that the LDP session between the two PEs is up, but the LDP label binding for the remote PE's loopback is not present. What is the most likely cause and correct action?

Medium
189

Which RSVP-TE filter style is commonly used for MPLS-TE tunnels to allow multiple senders on the same session?

Medium
190

In MPLS-TE Fast Reroute (FRR), what is a 'detour'?

Easy
191

In EVPN-VPWS, which identifier is used to uniquely identify an Ethernet Segment for multi-homing?

Medium
192

In SRv6, which SID behavior is used to achieve L3VPN IPv6 VPN forwarding, where the SID points to a VPN instance and performs decapsulation and IPv6 lookup?

Hard
193

In EVPN-VPWS, which component is used to identify a multi-homed Ethernet segment and enable load balancing and fast convergence?

Medium

Frequently asked questions

What does the MPLS and Segment Routing domain cover on the 350-501 exam?
Routing questions usually test route selection (administrative distance, metric), how static routes are configured and when they are preferred over dynamic routing.
How many questions are in this domain?
This page lists all 193 MPLS and Segment Routing questions in the 350-501 question bank. The actual exam draws from this domain proportionally to its weighting in the official exam blueprint.
What is the best way to practise this domain?
Start with a short focused session (10 questions) to identify gaps, then work through explanations. Repeat with a longer session once the weak areas feel solid.
Can I practise only MPLS and Segment Routing questions?
Yes — the session launcher on this page filters questions to this domain only. Choose any session length for inline explanations and scoring.
Cisco SPCOR / CCNP Service Provider Core 350-501 MPLS and Segment Routing Practice Questions