Cisco 350-501 Practice Test 46
Question 450
For an original SPCOR service-provider engineering scenario, consider: An SRv6 edge advertises an endpoint behavior using an unassigned locator block, and a remote ingress cannot route IPv6 segment packets to that function. Select TWO complementary steps: the targeted correction and its strongest prechange validation.
- Check: Check IPv6 locator advertisements, SID behavior, encapsulation and decapsulation and gateway forwarding for a test VPN or steered flow.
- Change: Configure supported RSVP local protection mechanisms and verify that a prepared bypass or detour can protect the intended link or node.
- Change: Allocate routable SRv6 locators and supported endpoint behaviors and design explicit interworking for differing SR data planes.
- Check: Compare computed repair SIDs, protected resource, postfailure path and packet-loss duration under a lab failure.
- Copy raw SR-MPLS labels into IPv6 destination addresses and call it SRv6 interworking with no locator or endpoint function design.
Explanation
Correct Answer
A:SRv6 encodes endpoint functions in IPv6 SIDs and uSID compresses supported behavior sequences; interworking gateways translate service or transport context between domains. Required intervention: Allocate routable SRv6 locators and supported endpoint behaviors and design explicit interworking for differing SR data planes.
C:SRv6 encodes endpoint functions in IPv6 SIDs and uSID compresses supported behavior sequences; interworking gateways translate service or transport context between domains. Evidence: Check IPv6 locator advertisements, SID behavior, encapsulation and decapsulation and gateway forwarding for a test VPN or steered flow.
Incorrect Answers
B:This option addresses a different service provider engineering topic (RSVP TE fast reroute and local protection) rather than the documented SRv6 locators uSID and interworking gateway decision.
D:Check: Compare computed repair SIDs, protected resource, postfailure path and packet-loss duration under a lab failure. SRv6 encodes endpoint functions in IPv6 SIDs and uSID compresses supported behavior sequences; interworking gateways translate service or transport context between domains.
E:For this select two assessment, the shortcut changes or bypasses the necessary routing, service or operational boundary rather than correcting it. Applied case: An SRv6 edge advertises an endpoint behavior using an unassigned locator block, and a remote ingress cannot route IPv6 segment packets to that function.
Question 451
A service provider network engineer is reviewing this backbone or customer-service scenario: A provider connects SR-MPLS and SRv6 islands but assumes a numeric MPLS label is automatically routable as an IPv6 uSID without a gateway function. A proposed shortcut is: Copy raw SR-MPLS labels into IPv6 destination addresses and call it SRv6 interworking with no locator or endpoint function design. What should the service provider engineer recommend as the narrowly scoped correction? Select ONE best answer.
- Interpret MPLS label operations, bottom-of-stack state and egress handling based on the signaled FEC and selected pop or explicit-null behavior.
- Use MPLS-aware OAM and label-stack inspection to verify LSP forwarding and localize transport failures separate from ordinary IP reachability.
- Allocate routable SRv6 locators and supported endpoint behaviors and design explicit interworking for differing SR data planes.
- Copy raw SR-MPLS labels into IPv6 destination addresses and call it SRv6 interworking with no locator or endpoint function design.
Explanation
Correct Answer
C:This targeted action addresses the observed service-provider control or forwarding gap without discarding necessary controls. Applied case: A provider connects SR-MPLS and SRv6 islands but assumes a numeric MPLS label is automatically routable as an IPv6 uSID without a gateway function.
Incorrect Answers
A:Interpret MPLS label operations, bottom-of-stack state and egress handling based on the signaled FEC and selected pop or explicit-null behavior. This option addresses a different service provider engineering topic (MPLS forwarding labels PHP explicit-null and TTL) rather than the documented SRv6 locators uSID and interworking gateway decision. The case-specific mechanism is: SRv6 encodes endpoint functions in IPv6 SIDs and uSID compresses supported behavior sequences; interworking gateways translate service or transport context between domains. The relevant action is: Allocate routable SRv6 locators and supported endpoint behaviors and design explicit interworking for differing SR data planes. Discriminating evidence: Check IPv6 locator advertisements, SID behavior, encapsulation and decapsulation and gateway forwarding for a test VPN or steered flow. Applied case: A provider connects SR-MPLS and SRv6 islands but assumes a numeric MPLS label is automatically routable as an IPv6 uSID without a gateway function.
B:Use MPLS-aware OAM and label-stack inspection to verify LSP forwarding and localize transport failures separate from ordinary IP reachability. SRv6 encodes endpoint functions in IPv6 SIDs and uSID compresses supported behavior sequences; interworking gateways translate service or transport context between domains.
D:SRv6 encodes endpoint functions in IPv6 SIDs and uSID compresses supported behavior sequences; interworking gateways translate service or transport context between domains. Applied case: A provider connects SR-MPLS and SRv6 islands but assumes a numeric MPLS label is automatically routable as an IPv6 uSID without a gateway function.
Question 452
A Cisco service provider design review finds: A provider connects SR-MPLS and SRv6 islands but assumes a numeric MPLS label is automatically routable as an IPv6 uSID without a gateway function. The team proposes: Allocate routable SRv6 locators and supported endpoint behaviors and design explicit interworking for differing SR data planes. Which engineering principle most strongly supports the recommended response? Select ONE best answer.
- A node SID follows IGP shortest-path semantics, while an adjacency SID identifies a particular link local to its advertising router and must be reached in sequence.
- SR traffic engineering policies select candidate paths and instantiate explicit forwarding segments; configuration alone does not prove a policy is active or matched by traffic.
- SRv6 encodes endpoint functions in IPv6 SIDs and uSID compresses supported behavior sequences; interworking gateways translate service or transport context between domains.
- A Path Computation Element calculates constraints-based paths while the PCC enforces or requests them, and PCEP sessions and delegation govern their coordination.
Explanation
Correct Answer
C:Demonstrable success requires: Each IPv6 segment resolves to its intended endpoint and traffic crosses SR-MPLS to SRv6 boundaries using supported adaptation. Applied case: A provider connects SR-MPLS and SRv6 islands but assumes a numeric MPLS label is automatically routable as an IPv6 uSID without a gateway function.
Incorrect Answers
A:A node SID follows IGP shortest-path semantics, while an adjacency SID identifies a particular link local to its advertising router and must be reached in sequence. This option addresses a different service provider engineering topic (SR adjacency SID and explicit segment list composition) rather than the documented SRv6 locators uSID and interworking gateway decision. The case-specific mechanism is: SRv6 encodes endpoint functions in IPv6 SIDs and uSID compresses supported behavior sequences; interworking gateways translate service or transport context between domains. The relevant action is: Allocate routable SRv6 locators and supported endpoint behaviors and design explicit interworking for differing SR data planes. Discriminating evidence: Check IPv6 locator advertisements, SID behavior, encapsulation and decapsulation and gateway forwarding for a test VPN or steered flow. Applied case: A provider connects SR-MPLS and SRv6 islands but assumes a numeric MPLS label is automatically routable as an IPv6 uSID without a gateway function.
B:SR traffic engineering policies select candidate paths and instantiate explicit forwarding segments; configuration alone does not prove a policy is active or matched by traffic. This option addresses a different service provider engineering topic (SR policy candidate paths and SRTE endpoint steering) rather than the documented SRv6 locators uSID and interworking gateway decision. The case-specific mechanism is: SRv6 encodes endpoint functions in IPv6 SIDs and uSID compresses supported behavior sequences; interworking gateways translate service or transport context between domains. The relevant action is: Allocate routable SRv6 locators and supported endpoint behaviors and design explicit interworking for differing SR data planes. Discriminating evidence: Check IPv6 locator advertisements, SID behavior, encapsulation and decapsulation and gateway forwarding for a test VPN or steered flow. Applied case: A provider connects SR-MPLS and SRv6 islands but assumes a numeric MPLS label is automatically routable as an IPv6 uSID without a gateway function.
D:A Path Computation Element calculates constraints-based paths while the PCC enforces or requests them, and PCEP sessions and delegation govern their coordination. A provider connects SR-MPLS and SRv6 islands but assumes a numeric MPLS label is automatically routable as an IPv6 uSID without a gateway function.
Question 453
The service provider operations team has not yet approved a change. Current evidence indicates: A provider connects SR-MPLS and SRv6 islands but assumes a numeric MPLS label is automatically routable as an IPv6 uSID without a gateway function. Which evidence best tests the technical diagnosis before approving a disruptive change? Select ONE best answer.
- Check TE database attributes, unreserved bandwidth, ERO or path message and reservation errors across the candidate hops.
- Check IPv6 locator advertisements, SID behavior, encapsulation and decapsulation and gateway forwarding for a test VPN or steered flow.
- Inspect the active candidate, preference, BSID or policy steering rules, operational validity and flow path through the backbone.
- Compare computed repair SIDs, protected resource, postfailure path and packet-loss duration under a lab failure.
Explanation
Correct Answer
B:This check tests the actual routing, transport or service boundary before an operationally risky response. Applied case: A provider connects SR-MPLS and SRv6 islands but assumes a numeric MPLS label is automatically routable as an IPv6 uSID without a gateway function.
Incorrect Answers
A:Check TE database attributes, unreserved bandwidth, ERO or path message and reservation errors across the candidate hops. SRv6 encodes endpoint functions in IPv6 SIDs and uSID compresses supported behavior sequences; interworking gateways translate service or transport context between domains.
C:Inspect the active candidate, preference, BSID or policy steering rules, operational validity and flow path through the backbone. A provider connects SR-MPLS and SRv6 islands but assumes a numeric MPLS label is automatically routable as an IPv6 uSID without a gateway function.
D:Compare computed repair SIDs, protected resource, postfailure path and packet-loss duration under a lab failure. SRv6 encodes endpoint functions in IPv6 SIDs and uSID compresses supported behavior sequences; interworking gateways translate service or transport context between domains.
Question 454
A candidate correction has been tested and the platform team requires a post-change acceptance check. Original problem: A provider connects SR-MPLS and SRv6 islands but assumes a numeric MPLS label is automatically routable as an IPv6 uSID without a gateway function. The carrier operations owner needs positive and negative tests showing existing customer services remain available. Which acceptance result demonstrates correct service provider forwarding and control behavior without disrupting authorized workflows? Select ONE best answer.
- Protected traffic continues through a verified loop-free repair path while IGP converges to a stable new route.
- Traffic does not migrate onto the recovered path until a valid label-switched transport is available.
- A valid LSP is signaled on capacity-feasible links and impossible reservations are rejected rather than silently oversubscribed.
- Each IPv6 segment resolves to its intended endpoint and traffic crosses SR-MPLS to SRv6 boundaries using supported adaptation.
Explanation
Correct Answer
D:SRv6 encodes endpoint functions in IPv6 SIDs and uSID compresses supported behavior sequences; interworking gateways translate service or transport context between domains. The result must be validated using the documented device, service or access context.
Incorrect Answers
A:Protected traffic continues through a verified loop-free repair path while IGP converges to a stable new route. SRv6 encodes endpoint functions in IPv6 SIDs and uSID compresses supported behavior sequences; interworking gateways translate service or transport context between domains.
B:Traffic does not migrate onto the recovered path until a valid label-switched transport is available. A provider connects SR-MPLS and SRv6 islands but assumes a numeric MPLS label is automatically routable as an IPv6 uSID without a gateway function.
C:A valid LSP is signaled on capacity-feasible links and impossible reservations are rejected rather than silently oversubscribed. SRv6 encodes endpoint functions in IPv6 SIDs and uSID compresses supported behavior sequences; interworking gateways translate service or transport context between domains.
Question 455
An implementation sign-off request identifies the following problem: A provider connects SR-MPLS and SRv6 islands but assumes a numeric MPLS label is automatically routable as an IPv6 uSID without a gateway function. Which paired technical change and validation should close the implementation review? Select ONE best answer.
- Change: Use supported LDP session protection or targeted discovery with routed transport continuity and bounded recovery timers. Verify: Test link removal, targeted hello maintenance, TCP session state and alternate loopback reachability while measuring session churn.
- Change: Verify MPLS forwarding activation, LDP discovery and reachable transport addresses on every required core hop. Verify: Inspect LDP discovery and session state, transport address routing, label binding and hardware forwarding labels along the path.
- Change: Combine node and adjacency SIDs in a segment list with proper endpoint locality and imposed stack depth for an explicit steering requirement. Verify: Trace segment-list execution, SR label stack and the adjacency owner at each hop using a forced parallel-link test.
- Change: Allocate routable SRv6 locators and supported endpoint behaviors and design explicit interworking for differing SR data planes. Verify: Check IPv6 locator advertisements, SID behavior, encapsulation and decapsulation and gateway forwarding for a test VPN or steered flow.
Explanation
Correct Answer
D:The change is successful only when: Each IPv6 segment resolves to its intended endpoint and traffic crosses SR-MPLS to SRv6 boundaries using supported adaptation.
Incorrect Answers
A:Change: Use supported LDP session protection or targeted discovery with routed transport continuity and bounded recovery timers. SRv6 encodes endpoint functions in IPv6 SIDs and uSID compresses supported behavior sequences; interworking gateways translate service or transport context between domains.
B:Change: Verify MPLS forwarding activation, LDP discovery and reachable transport addresses on every required core hop. SRv6 encodes endpoint functions in IPv6 SIDs and uSID compresses supported behavior sequences; interworking gateways translate service or transport context between domains.
C:This option addresses a different service provider engineering topic (SR adjacency SID and explicit segment list composition) rather than the documented SRv6 locators uSID and interworking gateway decision.
Question 456
A service provider network engineer is reviewing this backbone or customer-service scenario: An EVPN PE can reach the remote loopback but a new customer MAC never appears at the other PE because the expected EVPN type-2 route is absent. A proposed shortcut is: Treat any BGP IPv4 unicast route as an automatic EVPN MAC advertisement without configuring the EVPN address family. What should the service provider engineer recommend as the narrowly scoped correction? Select ONE best answer.
- Advertise and import the proper EVPN MAC or IP reachability route type and associated route targets for the requested L2 or L3 service.
- Treat any BGP IPv4 unicast route as an automatic EVPN MAC advertisement without configuring the EVPN address family.
- Build the supported carrier-supporting-carrier transport and routing boundary, retaining customer-carrier control where intended and validating labeled reachability.
- Build selective route leaking or shared-service VRF connectivity with scoped route targets and explicit security controls for shared and internet paths.
Explanation
Correct Answer
A:This targeted action addresses the observed service-provider control or forwarding gap without discarding necessary controls. Applied case: An EVPN PE can reach the remote loopback but a new customer MAC never appears at the other PE because the expected EVPN type-2 route is absent.
Incorrect Answers
B:EVPN uses MP-BGP to signal Ethernet MAC or IP reachability and other service state; type-2 and type-5 serve different reachability functions. For this best change assessment, the shortcut changes or bypasses the necessary routing, service or operational boundary rather than correcting it.
C:Build the supported carrier-supporting-carrier transport and routing boundary, retaining customer-carrier control where intended and validating labeled reachability. EVPN uses MP-BGP to signal Ethernet MAC or IP reachability and other service state; type-2 and type-5 serve different reachability functions.
D:Build selective route leaking or shared-service VRF connectivity with scoped route targets and explicit security controls for shared and internet paths. EVPN uses MP-BGP to signal Ethernet MAC or IP reachability and other service state; type-2 and type-5 serve different reachability functions.
Question 457
A Cisco service provider design review finds: An EVPN PE can reach the remote loopback but a new customer MAC never appears at the other PE because the expected EVPN type-2 route is absent. The team proposes: Advertise and import the proper EVPN MAC or IP reachability route type and associated route targets for the requested L2 or L3 service. Which engineering principle most strongly supports the recommended response? Select ONE best answer.
- Inter-AS L3VPN designs extend VPN signaling across AS boundaries with option-specific control-plane and label requirements; route visibility does not alone prove data-plane continuity.
- L3VPN extranet services require controlled cross-VRF routing and return reachability; sharing a few service routes need not grant full tenant-to-tenant visibility.
- EVPN uses MP-BGP to signal Ethernet MAC or IP reachability and other service state; type-2 and type-5 serve different reachability functions.
- G.8032 Ethernet Ring Protection controls blocked and active ring links, while Ethernet OAM provides fault detection and service continuity evidence.
Explanation
Correct Answer
C:Demonstrable success requires: Customer MACs or prefixes resolve to the appropriate remote PE without leaking between unrelated EVPN instances. Applied case: An EVPN PE can reach the remote loopback but a new customer MAC never appears at the other PE because the expected EVPN type-2 route is absent.
Incorrect Answers
A:Inter-AS L3VPN designs extend VPN signaling across AS boundaries with option-specific control-plane and label requirements; route visibility does not alone prove data-plane continuity. EVPN uses MP-BGP to signal Ethernet MAC or IP reachability and other service state; type-2 and type-5 serve different reachability functions.
B:L3VPN extranet services require controlled cross-VRF routing and return reachability; sharing a few service routes need not grant full tenant-to-tenant visibility. EVPN uses MP-BGP to signal Ethernet MAC or IP reachability and other service state; type-2 and type-5 serve different reachability functions.
D:G.8032 Ethernet Ring Protection controls blocked and active ring links, while Ethernet OAM provides fault detection and service continuity evidence. EVPN uses MP-BGP to signal Ethernet MAC or IP reachability and other service state; type-2 and type-5 serve different reachability functions.
Question 458
The service provider operations team has not yet approved a change. Current evidence indicates: An EVPN PE can reach the remote loopback but a new customer MAC never appears at the other PE because the expected EVPN type-2 route is absent. Which evidence best tests the technical diagnosis before approving a disruptive change? Select ONE best answer.
- Compare imported RT lists, VRF next hops, shared service return routing and firewall policy using two customer tenants.
- Compare ESI advertisements, DF election, MAC mobility sequence and traffic behavior before and after one PE uplink failure.
- Map UNI endpoints and approved source-destination pairs, then test leaf-to-leaf and root-to-leaf reachability in the staged EVC.
- Check EVPN address-family advertisements, route types, Ethernet segment and EVI context, route targets and remote forwarding database.
Explanation
Correct Answer
D:Confirm afterward that: Customer MACs or prefixes resolve to the appropriate remote PE without leaking between unrelated EVPN instances. Applied case: An EVPN PE can reach the remote loopback but a new customer MAC never appears at the other PE because the expected EVPN type-2 route is absent.
Incorrect Answers
A:Compare imported RT lists, VRF next hops, shared service return routing and firewall policy using two customer tenants. EVPN uses MP-BGP to signal Ethernet MAC or IP reachability and other service state; type-2 and type-5 serve different reachability functions.
B:Compare ESI advertisements, DF election, MAC mobility sequence and traffic behavior before and after one PE uplink failure. EVPN uses MP-BGP to signal Ethernet MAC or IP reachability and other service state; type-2 and type-5 serve different reachability functions.
C:Map UNI endpoints and approved source-destination pairs, then test leaf-to-leaf and root-to-leaf reachability in the staged EVC. EVPN uses MP-BGP to signal Ethernet MAC or IP reachability and other service state; type-2 and type-5 serve different reachability functions.
Question 459
A candidate correction has been tested and the platform team requires a post-change acceptance check. Original problem: An EVPN PE can reach the remote loopback but a new customer MAC never appears at the other PE because the expected EVPN type-2 route is absent. The carrier operations owner needs positive and negative tests showing existing customer services remain available. Which acceptance result demonstrates correct service provider forwarding and control behavior without disrupting authorized workflows? Select ONE best answer.
- Customer MACs or prefixes resolve to the appropriate remote PE without leaking between unrelated EVPN instances.
- Only authorized receiving VPN sites get the multicast data and replication uses the intended provider transport resources.
- Customers reach only approved shared services and internet egress while peer-to-peer tenant access remains restricted.
- Each customer's original VLAN identity is preserved or intentionally translated and service isolation remains intact across the provider.
Explanation
Correct Answer
A:EVPN uses MP-BGP to signal Ethernet MAC or IP reachability and other service state; type-2 and type-5 serve different reachability functions. Applied case: An EVPN PE can reach the remote loopback but a new customer MAC never appears at the other PE because the expected EVPN type-2 route is absent.
Incorrect Answers
B:Only authorized receiving VPN sites get the multicast data and replication uses the intended provider transport resources. EVPN uses MP-BGP to signal Ethernet MAC or IP reachability and other service state; type-2 and type-5 serve different reachability functions.
C:Customers reach only approved shared services and internet egress while peer-to-peer tenant access remains restricted. EVPN uses MP-BGP to signal Ethernet MAC or IP reachability and other service state; type-2 and type-5 serve different reachability functions.
D:Each customer's original VLAN identity is preserved or intentionally translated and service isolation remains intact across the provider. EVPN uses MP-BGP to signal Ethernet MAC or IP reachability and other service state; type-2 and type-5 serve different reachability functions.
Question 460
For an original SPCOR service-provider engineering scenario, consider: An EVPN PE can reach the remote loopback but a new customer MAC never appears at the other PE because the expected EVPN type-2 route is absent. Select TWO complementary steps: the targeted correction and its strongest prechange validation.
- Change: Build selective route leaking or shared-service VRF connectivity with scoped route targets and explicit security controls for shared and internet paths.
- Treat any BGP IPv4 unicast route as an automatic EVPN MAC advertisement without configuring the EVPN address family.
- Change: Advertise and import the proper EVPN MAC or IP reachability route type and associated route targets for the requested L2 or L3 service.
- Check: Trace VPNv4 advertisements, ASBR or RR roles, per-hop label stack and route-target import on a two-AS test topology.
- Check: Check EVPN address-family advertisements, route types, Ethernet segment and EVI context, route targets and remote forwarding database.
Explanation
Correct Answer
C:Acceptance: Customer MACs or prefixes resolve to the appropriate remote PE without leaking between unrelated EVPN instances. Applied case: An EVPN PE can reach the remote loopback but a new customer MAC never appears at the other PE because the expected EVPN type-2 route is absent.
E:Acceptance: Customer MACs or prefixes resolve to the appropriate remote PE without leaking between unrelated EVPN instances. EVPN uses MP-BGP to signal Ethernet MAC or IP reachability and other service state; type-2 and type-5 serve different reachability functions.
Incorrect Answers
A:Change: Build selective route leaking or shared-service VRF connectivity with scoped route targets and explicit security controls for shared and internet paths. EVPN uses MP-BGP to signal Ethernet MAC or IP reachability and other service state; type-2 and type-5 serve different reachability functions.
B:EVPN uses MP-BGP to signal Ethernet MAC or IP reachability and other service state; type-2 and type-5 serve different reachability functions. Use this instead: Advertise and import the proper EVPN MAC or IP reachability route type and associated route targets for the requested L2 or L3 service.
D:Check: Trace VPNv4 advertisements, ASBR or RR roles, per-hop label stack and route-target import on a two-AS test topology. EVPN uses MP-BGP to signal Ethernet MAC or IP reachability and other service state; type-2 and type-5 serve different reachability functions.
