350-501 Practice Test 4 — 25 Questions

Question 1

A service provider is implementing network slicing for 5G services. Which of the following is NOT a typical characteristic of a network slice?

Accepted Answer

Slices require dedicated physical infrastructure per slice.. Network slicing in 5G is built on network function virtualization (NFV) and software-defined networking (SDN), allowing multiple logical networks to share the same physical infrastructure. Each slice is a virtualized, isolated instance with its own resources and performance characteristics, so requiring dedicated physical infrastructure per slice contradicts the fundamental efficiency and flexibility that slicing provides. Therefore, option C is NOT a typical characteristic.

Answer

Each slice can have its own dedicated virtualized functions and resources.

Answer

Slices can be customized for specific service types like eMBB, uRLLC, or mMTC.

Answer

Slices are isolated from each other in terms of performance and security.

Question 2

An operator notices that a new MPLS-TE tunnel is not being established. The tunnel configuration includes a dynamic path option and a bandwidth of 100 Mbps. The network uses RSVP-TE with CSPF. The link-state database shows sufficient reservable bandwidth on all links along the calculated path. What is the most likely cause of the tunnel establishment failure?

Accepted Answer

RSVP-TE is not enabled on the transit interfaces. RSVP-TE must be explicitly enabled on every interface that will participate in MPLS-TE label-switched path (LSP) signaling. Even if the link-state database shows sufficient reservable bandwidth, without RSVP-TE enabled on transit interfaces, the PATH messages cannot be processed, and the tunnel will fail to establish. This is a common misconfiguration when deploying MPLS-TE.

Answer

The path option is misconfigured with a strict explicit path

Answer

MPLS LDP is not enabled on the core routers

Answer

The tunnel source interface is not configured with an IP address

Question 3

A service provider is implementing MAP-T (Mapping of Address and Port using Translation) to transition customers from IPv4 to IPv6. Which two characteristics of MAP-T are true? (Choose two.)

Accepted Answer

MAP-T employs a Border Router that performs translation between IPv4 and IPv6. MAP-T uses stateful or stateless translation between IPv4 and IPv6, and it uses a Border Router (BR) that performs translation. MAP-T does not use encapsulation; it uses translation (NAT). MAP-T also uses a Domain Name System (DNS) but that is not unique. The key characteristics: it uses a BR for translation and can be stateless.

Answer

MAP-T is primarily used for IPv6-to-IPv4 communication only

Answer

MAP-T requires a dedicated IPv6 prefix for each customer

Answer

MAP-T uses encapsulation to transport IPv4 packets over an IPv6 network

Question 4

In IOS XR, which process is responsible for managing the configuration database and commit operations?

Accepted Answer

confd. In IOS XR, the confd process is responsible for managing the configuration database and commit operations. It handles configuration changes, validation, and commits, ensuring that the system configuration is consistent and applied atomically.

Answer

fman

Answer

sysmgr

Answer

rib

Question 5

Which MEF service type defines a point-to-point Ethernet connection, often used for business connectivity?

Accepted Answer

E-Line. E-Line is the MEF service type that defines a point-to-point Ethernet connection, providing a dedicated Ethernet Virtual Connection (EVC) between exactly two UNIs. It is the MEF equivalent of a point-to-point Ethernet private line and is commonly used for business connectivity such as site-to-site links and internet access. E-Line maps to services like Ethernet Private Line (EPL) and Ethernet Virtual Private Line (EVPL).

Answer

E-Tree

Answer

E-Access

Answer

E-LAN

Question 6

An ISP is implementing MAP-T to transition to IPv6. Which of the following best describes MAP-T?

Accepted Answer

It uses stateless translation between IPv4 and IPv6 at the network edge. MAP-T (Mapping of Address and Port using Translation) uses IPv4-IPv6 translation (stateless NAT64) to allow IPv4 devices to communicate over an IPv6 network. It is an IPv6 transition mechanism.

Answer

It encapsulates IPv6 packets in IPv4 headers for transport over an IPv4 core

Answer

It requires both IPv4 and IPv6 addresses on every router

Answer

It tunnels IPv4 packets over IPv6 using GRE

Question 7

Which RESTCONF HTTP method should be used to replace the entire configuration of a device interface?

Accepted Answer

PUT. In RESTCONF, the PUT method is used to replace an entire resource, such as a device interface configuration. When sent to the interface's resource URI, PUT overwrites the existing configuration with the payload provided, effectively replacing the whole interface configuration. This aligns with REST semantics where PUT is idempotent and replaces the target resource.

Answer

GET

Answer

DELETE

Answer

POST

Question 8

A service provider is experiencing suboptimal routing due to BGP route reflection. To improve path selection while maintaining IBGP scalability, which feature should be implemented?

Accepted Answer

BGP optimal route reflection (ORR). BGP optimal route reflection (ORR) improves path selection by allowing the route reflector to calculate the best path based on the IGP metric to the client's location, rather than using its own BGP table. This overcomes the suboptimal routing caused by standard route reflection, where the RR's best path may not be optimal for all clients, while still maintaining IBGP scalability by avoiding a full mesh.

Answer

BGP deterministic med

Answer

BGP next-hop-self

Answer

BGP add-path

Question 9

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.)

Accepted Answer

IP-VRF for each tenant.. Option B is correct because EVPN IRB requires an IP-VRF (Layer 3 VRF) per tenant to hold the tenant's IP routing table and to import/export IP prefixes via EVPN Type 5 (IP Prefix) routes, enabling inter-subnet routing across the fabric. Option C is correct because the IRB interface (Bridge Domain Interface / BDI) acts as the distributed anycast Layer 3 gateway for the tenant subnet, tying the Layer 2 bridge domain to the IP-VRF and sourcing the MAC/IP Advertisement (Type 2) routes used for ARP suppression and host mobility. Option E is correct because each tenant needs an Ethernet VPN Instance (EVI) with a unique Route Distinguisher (and typically a Route Target) to keep tenant MAC/IP and IP-prefix routes separate in BGP EVPN, ensuring proper isolation and import/export of routes. Option A is not essential because EVPN IRB relies on BGP EVPN for MAC/IP and IP-prefix signaling, not on LDP or SR for label distribution; MPLS or VXLAN encapsulation can be used, but LDP/SR is not a required component. Option D is not essential because MPLS-TE tunnels are an optional transport optimization and are not required for EVPN IRB operation, which can run over plain MPLS, VXLAN, or other underlays.

Answer

LDP or SR for label distribution.

Answer

MPLS-TE tunnels for transport.

Question 10

In the context of IOS XR commit/rollback configuration model, which command is used to apply a set of configuration changes as a single atomic operation?

Accepted Answer

commit. In IOS XR's two-stage configuration model, the 'commit' command applies the candidate configuration to the running configuration as a single atomic transaction. All changes in the target configuration are validated and applied together, or none are applied if validation fails. This atomicity is the defining feature of IOS XR's commit-based model.

Answer

save config

Answer

apply-changes

Answer

copy running-config startup-config

Question 11

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

Accepted Answer

Perform IPv6 decapsulation and forward using a VPN IPv6 routing table.. End.DT6 is an SRv6 endpoint behavior that decapsulates an IPv6 packet and performs an IPv6 lookup in a specified VPN IPv6 routing table (VRF). It is used for IPv6 VPN services, allowing IPv6 payloads to be forwarded based on the VRF table. This behavior is defined in RFC 8986 and is the IPv6 counterpart to End.DT4.

Answer

Perform IPv4 decapsulation and forward using a VPN IPv4 table.

Answer

Perform IPv6 encapsulation and forward.

Answer

Perform IPv6 decapsulation and forward using the global IPv6 routing table.

Question 12

Refer to the exhibit. The router has an outgoing label of 'Pop' for prefix ***********. What does this imply?

Accepted Answer

The router is the penultimate hop and will remove the label before forwarding. When a router has an outgoing label of 'Pop' for a prefix in MPLS, it indicates that the router is the penultimate hop (PHP) in the LSP. PHP means the router will remove (pop) the top label before forwarding the packet to the next hop, reducing the burden on the egress LSR. This is standard MPLS behavior as per RFC 3031, where the egress router signals an implicit null label (label 3) to its upstream neighbor.

Answer

The router has not learned a label for that prefix

Answer

The router will not forward traffic for that prefix

Answer

The router will push a new label for that prefix

Question 13

Which technology allows an IPv6-only customer edge router to connect to an MPLS provider edge router using IPv4 transport, encapsulating IPv6 packets in MPLS with a labeled IPv4 next-hop?

Accepted Answer

6PE. 6PE (IPv6 Provider Edge) allows an IPv6-only customer edge (CE) router to connect to an MPLS provider edge (PE) router that uses an IPv4 core. The PE router encapsulates IPv6 packets from the CE into MPLS labels, with the outer label corresponding to an IPv4 next-hop (the PE's IPv4 address). This enables IPv6 traffic to traverse an IPv4 MPLS backbone without requiring IPv6 on the core routers.

Answer

6VPE

Answer

NAT64

Answer

MAP-T

Question 14

Refer to the exhibit. A PE router is showing a VRF route. What does the [200/0] indicate?

Accepted Answer

Administrative distance 200 and metric 0. In the VRF route output, the [200/0] notation represents the administrative distance (200) and the metric (0) for the route. The administrative distance is a trustworthiness value used by the router to select the best path when multiple routing protocols provide routes to the same destination; a lower value is preferred. The metric is a protocol-specific cost, and here it is 0, indicating a directly connected or very low-cost path within the VRF.

Answer

Local preference 200 and MED 0

Answer

Label value 200 and metric 0

Answer

AS path length 200 and weight 0

Question 15

An OSPF network is configured with RSVP-TE. Which OSPF extension is used to advertise TE link attributes such as bandwidth and administrative group?

Accepted Answer

OSPF Type 10 Opaque LSA. OSPF Type 10 Opaque LSAs are used to carry traffic engineering (TE) link attributes such as bandwidth and administrative group. These LSAs are area-scoped and are flooded within the OSPF area to advertise TE information for RSVP-TE. This allows the OSPF network to support MPLS TE by distributing link attributes.

Answer

OSPF Type 1 LSA

Answer

OSPF Type 5 LSA

Answer

OSPF Type 7 LSA

Question 16

An SP is deploying EVPN to provide both L2 and L3 VPN services. Which advantage does EVPN offer over traditional VPLS for multi-homing?

Accepted Answer

EVPN provides faster convergence and active-active multi-homing using Ethernet Segment Identifier (ESI) and Designated Forwarder (DF) election.. EVPN uses ESI-based multi-homing with BGP control plane, offering faster convergence and active-active load balancing compared to VPLS's active/standby model.

Answer

EVPN uses a single MAC address per PE to reduce forwarding table size.

Answer

EVPN supports only active/standby redundancy, similar to VPLS.

Answer

EVPN requires MPLS in the core, whereas VPLS can use IP-only.

Question 17

Which NETCONF operation is used to retrieve the entire running configuration from a network device?

Accepted Answer

get-config. The NETCONF `get-config` operation is specifically designed to retrieve a configuration datastore, such as the running configuration. Unlike the `get` operation, which retrieves both configuration and state data, `get-config` targets only the configuration data, making it the precise operation for fetching the entire running configuration from a network device.

Answer

get

Answer

commit

Answer

edit-config

Question 18

An engineer configures a class-map to match traffic with DSCP AF41. What is the numerical DSCP value for AF41?

Accepted Answer

34. AF41 is Assured Forwarding class 4, low drop probability, with DSCP decimal value 34 (binary 100010).

Answer

38

Answer

36

Answer

32

Question 19

A service provider uses BGP route reflectors to scale iBGP. A route reflected from a route reflector arrives at a client with the originator-id set. What is the purpose of the originator-id attribute?

Accepted Answer

To prevent routing loops by ensuring the route is not accepted if the originator-id matches the local router-id. The originator-id is set by the route reflector to the router-id of the originating router in the AS. It prevents routing loops by allowing a route to be ignored if the originator-id matches the receiving router's ID.

Answer

To identify the route reflector that reflected the route

Answer

To indicate the cluster-id of the route reflector

Answer

To carry the next-hop information for IPv6 prefixes

Question 20

A service provider is implementing QoS on an MPLS network to support voice, video, and data traffic. Which queuing mechanism provides the lowest latency for real-time traffic?

Accepted Answer

LLQ. LLQ (Low Latency Queuing) is the correct choice because it provides a strict priority queue specifically designed for real-time traffic like voice and video. By placing delay-sensitive packets into a dedicated priority queue that is serviced before all other queues, LLQ ensures minimal and predictable latency, which is essential for maintaining voice quality in an MPLS network.

Answer

FIFO

Answer

WRED

Answer

CBWFQ