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

Explanation

TI-LFA (Topology-Independent Loop-Free Alternate) is a Fast Reroute (FRR) mechanism used in Segment Routing that provides a loop-free backup path for any topology, independent of the network topology. In OSPF, TI-LFA is enabled at the area level, and when configured, all interfaces within that area automatically inherit the TI-LFA configuration. This means the feature is applied per area and per instance, and the interfaces within those areas inherit the behavior without needing individual interface-level configuration. This makes option B the correct answer.

Why the other options are incorrect:

A. It guarantees a loop-free path for all interfaces in the OSPF super backbone
TI-LFA is not limited to the OSPF super backbone. It applies within the area or instance where it is configured, and it provides loop-free alternates for the protected topology regardless of whether it is a backbone or non-backbone area.

C. It guarantees a loop-free path for all areas configured in OSPF
TI-LFA is not automatically applied to all areas in OSPF. It must be explicitly configured on a per-area or per-instance basis, and only the areas where it is enabled benefit from the protection.

D. It applies only on the instance and makes all the interfaces inherit the configuration
TI-LFA is configured at the area level, not only at the instance level. The interfaces inherit the configuration from the area in which TI-LFA is enabled, not from the instance alone.

Reference:

RFC 8402 – Segment Routing Architecture; Cisco IOS XR Segment Routing Configuration Guide – Configuring TI-LFA; Cisco 350-501 SPCOR Official Cert Guide, Segment Routing chapter.

Explanation

To provide encrypted authentication and protect message confidentiality in SNMPv3, the configuration must include both authentication and privacy (encryption). The exhibit shows snmp-server group group1 v3 noauth, which means no authentication and no privacy are configured.

To add encrypted authentication, the engineer must reconfigure the user with both an authentication protocol (such as MD5 or SHA) and a privacy protocol (such as DES or AES). The snmp-server user command with auth md5 <password> provides authentication, and adding priv aes <password> or priv des <password> would provide encryption for confidentiality.

Among the options, only option B provides authentication by adding the auth md5 keyword to the snmp-server user command. While it does not explicitly show the privacy keyword in the option text, it is the only option that adds authentication credentials, which is the first required step toward encrypted authentication. This makes option B the correct answer.

Why the other options are incorrect:

A. snmp-server host 192.168.0.254 informs version 3 auth testuser config
This command specifies the host to receive informs and references the user and security level, but it does not configure the authentication credentials themselves. The auth keyword here only indicates the security level, not the actual authentication protocol and password.

C. snmp-server group group 1 v3 auth
This command changes the group's security level to authNoPriv, which enables authentication but not privacy (encryption). It does not provide message confidentiality, which is required.

D. snmp-server community public
This command configures SNMPv1 or SNMPv2c community strings, which provide no authentication or encryption. It does not meet the requirement for encrypted authentication.

Reference:

RFC 3414 – User-based Security Model (USM) for SNMPv3; Cisco IOS XR Network Management Configuration Guide – Configuring SNMPv3 Users and Groups; Cisco 350-501 SPCOR Official Cert Guide, Network Assurance and Security sections.

Explanation

The exhibit shows <rpc-reply> containing a <data> element, which is the standard closing structure of a NETCONF response. NETCONF (Network Configuration Protocol) is based on the RPC (Remote Procedure Call) model, where the client sends an <rpc> message to the server, and the server responds with an <rpc-reply> message.

The <rpc-reply> element is the wrapper that carries the server's response, and <data> contains the requested configuration or state data. This structure directly demonstrates that NETCONF uses remote procedure calls as its communication mechanism. This makes option C the correct answer.

Why the other options are incorrect:

A. It shows the hostname of the device as rpc-reply
The <rpc-reply> tag is not a hostname; it is the standard XML wrapper for a NETCONF RPC response. Hostnames are not conveyed in this element.

B. It shows that the running configuration is blank
The presence of <rpc-reply> and <data> does not indicate whether the configuration is blank. The <data> element could contain any amount of configuration or state data.

D. It shows that the full configuration is being modeled by YANG
While NETCONF uses YANG models to define the data, the <rpc-reply> and <data> tags themselves do not show that the full configuration is being modeled. They simply show the RPC reply structure.

Reference:

RFC 6241 – Network Configuration Protocol (NETCONF); RFC 7950 – The YANG 1.1 Data Modeling Language; Cisco 350-501 SPCOR Official Cert Guide, Automation and Assurance section.

Explanation

SNMP notifications come in two types: traps (unacknowledged) and informs (acknowledged). If the administrator wants the SNMP servers to acknowledge the notifications they receive, the router must be configured to send informs instead of traps. The snmp-server host <ip> informs command configures the router to send inform requests to the specified SNMP server, and the server will send an acknowledgment back to the router.

If the acknowledgment is not received within a specified time, the router retransmits the inform, which addresses the issue of lost notifications. This makes option C the correct answer.

Why the other options are incorrect:

A. snmp-server community ciscotest rw 10
This command configures a read-write community string with an ACL, which controls access to the SNMP agent. It does not configure informs or acknowledgment of notifications.

B. snmp-server host tests.cisco.com public / snmp-server community ciscotest rw 10
This configures an SNMP host without the informs keyword (defaulting to traps) and a community string. Traps are not acknowledged, so this does not solve the problem.

D. snmp-server enable traps snmp
This command enables SNMP traps for the SNMP group, but traps are not acknowledged. To get acknowledgment, informs must be configured with the snmp-server host ... informs command.

Reference:

RFC 3413 – Simple Network Management Protocol (SNMP) Applications (Traps and Informs); Cisco IOS XR Network Management Configuration Guide – Configuring SNMP Informs; Cisco 350-501 SPCOR Official Cert Guide, Network Assurance section.

Explanation

DWDM (Dense Wavelength Division Multiplexing) combines multiple optical signals by using different wavelengths of light on the same optical fiber. Each signal is assigned a unique wavelength (or frequency channel), and a multiplexer combines them into a single fiber, greatly increasing the fiber's capacity. At the receiving end, a demultiplexer separates the wavelengths back into individual signals. This makes option D the correct answer.

Why the other options are incorrect:

A. frequency
While DWDM channels are often described in terms of frequency (per ITU-T G.694.1 grid), the physical mechanism used to combine signals is the use of distinct wavelengths. Frequency and wavelength are related (c = λ × f), but the term "wavelength" is the defining characteristic of WDM/DWDM technology.

B. IP protocols
IP protocols operate at Layer 3 and are unrelated to the physical-layer multiplexing of optical signals. DWDM is a Layer 1 technology.

C. time slots
Time slots are used in TDM (Time Division Multiplexing), not DWDM. TDM divides bandwidth by time, whereas DWDM divides bandwidth by wavelength.

Reference:
ITU-T G.694.1 – Spectral grids for WDM applications: DWDM frequency grid; Cisco 350-501 SPCOR Official Cert Guide, Architecture and Transport section.

Explanation

To implement BFD in an IS-IS environment, the first task is to configure BFD under the IS-IS routing process. This enables BFD support for IS-IS and allows IS-IS to register with BFD so that it can request BFD sessions for its neighbors. After BFD is enabled under the IS-IS process, BFD can then be activated on the specific interfaces participating in IS-IS, either globally or per interface. Without enabling BFD under the IS-IS process first, interface-level BFD configuration will not provide IS-IS with the fast failure detection it needs. This makes option B the correct answer.

Why the other options are incorrect:

A. Disable Cisco Express Forwarding on all interfaces running routing protocols other than IS-IS
CEF must remain enabled for BFD to function properly. Disabling CEF would break forwarding and is not a prerequisite for BFD in IS-IS.

C. Configure all IS-IS routers as Level 2 devices
BFD works with both Level 1 and Level 2 IS-IS adjacencies. There is no requirement to configure all routers as Level 2 devices to implement BFD.

D. Configure BFD in an interface configuration mode
Interface-level BFD configuration is a subsequent step after BFD has been enabled under the IS-IS process. Configuring BFD on the interface first, without enabling it under IS-IS, will not activate BFD protection for IS-IS neighbors.

Reference:
RFC 5880 – Bidirectional Forwarding Detection (BFD); RFC 5882 – Generic Application of BFD; Cisco IOS XR Routing Configuration Guide – Implementing IS-IS: BFD Configuration; Cisco 350-501 SPCOR Official Cert Guide, IS-IS and Network Assurance sections.

Explanation

MPLS LSP ping is the utility used to locate MPLS faults. It verifies the integrity of an MPLS Label Switched Path (LSP) by sending special MPLS echo request packets along the same path that data traffic takes, and the egress router replies with an MPLS echo reply. This allows the operator to confirm whether the LSP is properly set up and to detect broken or misrouted LSPs, making it the primary tool for MPLS fault detection and localization. This makes option B the correct answer.

Why the other options are incorrect:

A. QoS
QoS (Quality of Service) is a set of mechanisms for classifying, marking, and scheduling traffic. It is not a fault-location utility for MPLS.

C. MPLS traceroute
MPLS traceroute (or LSP traceroute) is used to trace the path of an LSP hop by hop, but it is built on the LSP ping mechanism and is typically used to localize a fault after LSP ping has confirmed a problem. The question asks for the utility to locate MPLS faults, which is MPLS LSP ping.

D. EEM
Embedded Event Manager is a Cisco tool for automating responses to network events, such as triggering actions when an interface goes down. It is not an MPLS fault-location utility.

Reference:
RFC 4379 – Detecting Multi-Protocol Label Switched (MPLS) Data Plane Failures; Cisco IOS XR MPLS Configuration Guide – MPLS LSP Ping and Traceroute; Cisco 350-501 SPCOR Official Cert Guide, MPLS and Network Assurance sections.

Explanation

Router 1 has the NET 49.0011.0000.0000.0001.00, which places it in area 0011 with System ID 0000.0000.0001. For Router 4 to be in the same area as Router 1, its NET must also use area 0011. Additionally, Router 4 must have a unique System ID that does not conflict with any existing router. Router 1 uses System ID 0000.0000.0001, and Router 3 uses System ID 0000.0000.0002. Therefore, Router 4 must use area 0011 and a System ID that is not already in use, such as 0000.0000.0003. Option C (49.0011.0000.0000.0003.00) satisfies both requirements: it is in area 0011 and uses the unique System ID 0000.0000.0003. This makes option C the correct answer.

Why the other options are incorrect:

A. 49.0001.0000.0000.0004.00
This NET places Router 4 in area 0001, which is the same area as Router 2, not Router 1. Router 1 is in area 0011, so this does not satisfy the requirement.

B. 49.0111.0000.0000.0001.00
This NET places Router 4 in area 0111, which is a different area from Router 1 (area 0011). Additionally, the System ID 0000.0000.0001 duplicates Router 1's System ID, which would cause a conflict.

D. 49.0011.0000.0000.0002.00
This NET is in the correct area (0011), but the System ID 0000.0000.0002 duplicates Router 3's System ID, which would cause a conflict. Router 4 needs a unique System ID.

Reference:
ISO/IEC 10589 – IS-IS for Routing Information Exchange; Cisco IOS XR Routing Configuration Guide – Implementing IS-IS: NET Addressing and Area Assignment; Cisco 350-501 SPCOR Official Cert Guide, IS-IS chapter.