Free Cisco 350-501 Practice Questions 2026 | Implementing and Operating Cisco Service Provider Network Core Technologies (350-501 SPCOR)

Explanation

The exhibit shows a class-map named VOIP that matches IP precedence 5, and a policy-map named MARK-TRAFFIC that references the VOIP class. The task is to complete the configuration for QoS class-based marking. Class-based marking uses the set command to assign a new marking value to the matched traffic. To mark VoIP traffic with the standard DSCP value for voice, the correct command is set dscp ef (Expedited Forwarding). This makes option A the correct answer.

Why the other options are incorrect:

B. PE-A(config-pmap-c)#fair-queue
Fair queueing is a congestion management (queuing) feature that provides fair bandwidth allocation among flows. It is not a marking command and does not complete a class-based marking configuration.

C. PE-A(config-pmap-c)#random-detect
Random Early Detection (RED) is a congestion avoidance mechanism that drops packets before a queue fills up. It is not a marking action.

D. PE-A(config-pmap-c)#priority
The priority command configures a low-latency queue (LLQ) for the class, providing priority treatment. It is a queuing/scheduling action, not a marking action, and the question specifically asks about class-based marking.

Reference:
Cisco IOS XR Modular QoS Configuration Guide – Configuring Class-Based Marking; RFC 2474 – Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers; Cisco 350-501 SPCOR Official Cert Guide, QoS section.

Explanation

The exhibit shows the engineer attempting to configure ospfv3 1 area 1 ipv4 on interface FastEthernet0/0, and the router returns the error % IPv6 routing not enabled. Although OSPFv3 has been extended to support IPv4 address families (using the ipv4 keyword in the address family configuration), Cisco IOS XR requires IPv6 routing to be enabled globally on the router before OSPFv3 can be activated on any interface, even for IPv4 address family support. Additionally, IPv6 must be enabled on the interface itself. Until ipv6 unicast-routing is configured globally and IPv6 is enabled on the interface, OSPFv3 will not run for IPv4 on FastEthernet0/0. This makes option B the correct answer.

Why the other options are incorrect:

A. In the ospfv3 1 area 1 ipv4 command, area 0 must be configured instead of area 1
There is no requirement that the area must be area 0. OSPFv3 areas can be any valid area number, and area 1 is acceptable. The error message is about IPv6 routing not being enabled, not about the area number.

C. OSPFv3 cannot be configured for IPv4; OSPFv3 works only for IPv6
This is incorrect. OSPFv3 has been extended with address family support (RFC 5838) to support IPv4 and IPv6. The ipv4 keyword in the command confirms that OSPFv3 can be used for IPv4.

D. "IPv6 routing not enabled" is just an informational message and OSPFv3 runs for IPv4 on interface FastEthernet0/0 anyway
The message is an error, not just informational. OSPFv3 will not run until IPv6 routing is enabled, so this statement is false.

Reference:
RFC 5838 – Support of Address Families in OSPFv3; Cisco IOS XR Routing Configuration Guide – Implementing OSPFv3: IPv4 Address Family Support; Cisco 350-501 SPCOR Official Cert Guide, OSPF chapter.

Explanation

The OSPF graceful restart helper router can be configured to terminate the restart process if it detects any changes in the link-state database (LSAs) during the restart. The command nsf ietf helper strict-lsa-checking enables this strict LSA checking behavior for the IETF graceful restart mechanism. When enabled, if the helper router detects an LSA change that affects the restarting router's adjacencies or the topology, it aborts the helper mode and terminates the graceful restart process, allowing normal OSPF convergence to occur instead. This makes option C the correct answer.

Why the other options are incorrect:

A. nsf ietf helper disable
This command disables the helper mode for IETF graceful restart, which is the opposite of what is required. It does not enable strict LSA checking.

B. nsf cisco enforce global
There is no such command as nsf cisco enforce global in standard Cisco OSPF graceful restart configuration. The Cisco-specific NSF commands differ from the IETF helper commands.

D. nsf Cisco helper disable
This command disables the Cisco-specific helper mode for graceful restart. It does not enable strict LSA checking to terminate the restart process.

Reference:
RFC 4811 – OSPF Out-of-Band LSDB Resynchronization; RFC 3623 – Graceful OSPF Restart; Cisco IOS XR Routing Configuration Guide – Implementing OSPF: Non-Stop Forwarding and Helper Mode; Cisco 350-501 SPCOR Official Cert Guide, OSPF and Network Assurance sections.

Explanation

Model-driven telemetry (MDT) is a push-based mechanism in which the network device continuously streams modeled data (using YANG models) to a collector on a configured interval, without the administrator having to poll for it. SNMP, by contrast, is primarily a pull-based mechanism where the manager polls the device (or receives traps/informs for specific events). The key difference described in option A is that telemetry allows modeled network data to be pushed to the network administrator (collector) on an as-needed or configured basis, which correctly reflects the push model and the use of YANG-modeled data in telemetry. This makes option A the correct answer.

Why the other options are incorrect:

B. Telemetry uses traps and inform messages to deliver data to a network administrator on a polling basis
Traps and informs are SNMP mechanisms, not telemetry. Telemetry is push-based and does not rely on traps/informs or polling.

C. SNMP uses the YANG data modeling language
SNMP uses MIBs (Management Information Bases) and SMI (Structure of Management Information), not YANG. YANG is used by NETCONF, RESTCONF, and model-driven telemetry.

D. SNMP pushes network data to the network administrator whenever it is queried
SNMP is pull-based (the manager queries the agent), not push-based. The phrase "pushes... whenever it is queried" is contradictory; if it is queried, it is a pull, not a push.

Reference:
RFC 7950 – The YANG 1.1 Data Modeling Language; RFC 3411–3418 – SNMPv3 Framework; Cisco IOS XR Telemetry Configuration Guide – Model-Driven Telemetry vs. SNMP; Cisco 350-501 SPCOR Official Cert Guide, Automation and Assurance section.

Explanation

The exhibit shows ip flow-export version 9 origin-as, which configures NetFlow version 9 export with the origin-as keyword. This keyword includes the origin AS information in the exported flow records, but it does not include the BGP next hop. To include the BGP next hop in the NetFlow export, the appropriate keyword (such as bgp-nexthop) must be explicitly added to the version 9 export configuration. NetFlow version 9 uses templates, and the specific fields to be exported must be defined; if the BGP next-hop keyword is not included, that field will not appear in the export statistics. This makes option D the correct answer.

Why the other options are incorrect:

A. Only the origin AS of the source router will be included in the export statistics
The configuration includes origin-as, which provides origin AS information, but this statement is not about the BGP next hop and does not address the issue described in the question.

B. Loopback 0 must be participating in BGP for it to be included in the export statistics
Loopback 0 is configured as the source of the NetFlow export, not as a BGP next-hop field. Whether Loopback 0 participates in BGP is irrelevant to including the BGP next hop in flow records.

C. The origin AS and the peer-as will be included in the export statistics
The configuration includes only origin-as, not peer-as. Therefore, the peer AS is not included in the export statistics, and this statement is false.

Reference:
Cisco IOS NetFlow Configuration Guide – NetFlow Version 9 Field Types and BGP Next-Hop Export; RFC 3954 – Cisco Systems NetFlow Services Export Version 9; Cisco 350-501 SPCOR Official Cert Guide, Network Assurance section.

Explanation

The requirements are: deny routes that are looped into ASN 65001 (contain 65001 in the AS_PATH) or have traversed 10 or more ASNs, deny routes that do not match the allowed prefix 2001:db8:aaaa::/48, and assign community 65001:200 to accepted routes. The correct route-policy must evaluate both denial conditions in a single `if` statement using `or`, then check the destination prefix, and finally set the community. Option A does this correctly: it denies routes where the AS_PATH length is 10 or more **or** the path passes through 65001 **or** the community matches 65001:100, then checks the destination `2001:db8:aaaa::/48`, passes (done) if it matches, drops otherwise, and sets community 65001:200. This makes option A the correct answer.

Why the other options are incorrect:

B. Option B
It uses `pass` instead of `done` for the matching prefix, which means the policy continues to evaluate and may apply unintended actions. It also places the prefix check after the denial, but the logic flow is not the standard IOS XR pattern for accepting only a specific prefix and then setting a community. The `pass` statement exits with an accept but does not guarantee the subsequent `set community` is applied in the same way as `done`.

C. Option C
It splits the denial conditions into two separate `if` blocks. While logically similar, it does not combine the loop and AS-path-length checks with `or` as required. More importantly, the community denial condition is separated, which changes the semantics and does not match the intended single combined denial.

D. Option D
It is missing the `endif` and `end-policy` structure in the correct order, and the logic is incomplete. The prefix check sets the community but does not properly handle the pass/drop decision for non-matching prefixes.

E. Option E
There is no Option E shown in the exhibit; the exhibit only contains four options (A through D). If a fifth option existed, it would need to match the exact logic of Option A.

Reference:
Cisco IOS XR Routing Configuration Guide – Implementing Routing Policy: Route-Policy Statements and Actions; RFC 4271 – A Border Gateway Protocol 4 (BGP-4); RFC 1997 – BGP Communities Attribute; Cisco 350-501 SPCOR Official Cert Guide, BGP and Routing Policy sections.

Explanation

The exhibit shows `show mpls ldp bindings 192.168.10.10/32` with a Local binding of `label: ImpNull`. The Implicit Null (ImpNull) label, which has the value of 0, is advertised by a router to its upstream LDP peer to indicate that the upstream router should perform Penultimate Hop Popping (PHP). This means the penultimate (second-to-last) router in the LSP will pop the MPLS label before forwarding the packet to the ultimate hop (the egress router for the prefix). Since the label is popped by the penultimate router, the Implicit Null label itself is not part of the MPLS label stack carried in the packet when it reaches the egress router. This makes options A and D the correct answers.

Why the other options are incorrect:

B. Ultimate Hop Popping is in use for the prefix displayed
Ultimate Hop Popping (UHP) is the opposite of PHP. In UHP, the egress router pops the label itself, and the Implicit Null label would not be advertised. The presence of ImpNull indicates PHP, not UHP.

C. Label 0 is used for the prefix displayed and will be part of the MPLS label stack for packets destined for 192.168.10.10
The Implicit Null label (label 0) is signaled to the upstream peer but is not pushed onto the label stack. The upstream router pops the label instead of swapping it to label 0, so label 0 does not appear in the label stack of the forwarded packet.

E. Label 3 is in use for the prefix displayed and will be part of the MPLS label stack for packets destined for 192.168.10.10
Label 3 is the Explicit Null label used for certain QoS signaling scenarios, but it is not shown in the exhibit. The exhibit shows ImpNull (label 0), not label 3.

Reference:
RFC 3031 – Multiprotocol Label Switching Architecture (Implicit Null and PHP); RFC 5036 – LDP Specification; Cisco IOS XR MPLS Configuration Guide – Implementing LDP: Label Advertisement and PHP; Cisco 350-501 SPCOR Official Cert Guide, MPLS chapter.

Explanation

In a multi-vendor PIM-SM environment, the engineer must implement BSR (Bootstrap Router) so that devices can dynamically learn the Rendezvous Point (RP). BSR is a standards-based mechanism defined in RFC 5059, where candidate RPs send their candidacy to the Bootstrap Router, and the BSR floods RP-to-group mapping information to all PIM routers in the domain via bootstrap messages. Because BSR is an open standard, it is the correct choice for a multi-vendor environment, unlike Cisco-proprietary Auto-RP. This makes option D the correct answer.

Why the other options are incorrect:

A. Auto-RP
Auto-RP is a Cisco-proprietary mechanism for dynamic RP learning. It works well in all-Cisco environments but is not suitable for a multi-vendor environment because non-Cisco devices do not support it.

B. BIDIR-PIM
Bidirectional PIM is a PIM mode used for many-to-many communication. While it uses an RP, it does not provide a dynamic RP learning mechanism by itself; it still relies on static RP configuration or BSR/Auto-RP.

C. SSM
Source-Specific Multicast does not use an RP at all. Receivers join a specific source and group directly using IGMPv3, so there is no RP to learn dynamically.

Reference:
RFC 5059 – Bootstrap Router (BSR) Mechanism for PIM; Cisco IOS XR Multicast Configuration Guide – Configuring BSR; Cisco 350-501 SPCOR Official Cert Guide, Multicast chapter.

Explanation

For two IS-IS Level 2 routers to form an adjacency, the authentication settings and the hello timer settings must match on both sides. Authentication must match because the hello PDUs carry authentication information, and if the authentication type or password differs, the hello packets will be rejected and no adjacency will form. The hello timer setting must also match because IS-IS hello PDUs carry the hello interval, and a mismatch causes the routers to disagree on how frequently hello packets should be sent, preventing the adjacency from staying up. This makes options A and E the correct answers.

Why the other options are incorrect:

B. Area ID
Area ID must match only for Level 1 adjacencies. Level 2 adjacencies are formed between routers in different areas, and the area ID does not need to match for Level 2 peering.

C. System ID
System IDs must be unique within the IS-IS domain; they do not need to match. In fact, if two routers had the same system ID, it would cause a conflict and prevent proper adjacency formation.

D. MTU
MTU is not a parameter that must match for IS-IS adjacency formation in general, unlike OSPF where MTU mismatch can block adjacency. IS-IS can form adjacencies even when MTUs differ, though large LSPs may be fragmented or dropped if the MTU is too small.

Reference:
ISO/IEC 10589 – IS-IS for Routing Information Exchange; Cisco IOS XR Routing Configuration Guide – Implementing IS-IS: Adja