350-501 Practice Test 4 — 10 Questions

Question 1

Drag and drop the steps to configure a Layer 3 interface on a Cisco switch (SVI) into the correct order.

Accepted Answer

Create the VLAN, then enter interface VLAN mode, then assign IP address, then enable the interface.. SVI configuration requires creating the VLAN, then the interface VLAN, assigning an IP, and enabling it.

Answer

Enter interface VLAN mode, then assign IP address, then enable the interface, then create the VLAN.

Answer

Create the VLAN, then assign IP address, then enter interface VLAN mode, then enable the interface.

Answer

Create the VLAN, then enable the interface, then enter interface VLAN mode, then assign IP address.

Question 2

A service provider wants to provide Layer 3 VPN services to customers using MPLS. Which technology is used to distribute VPNv4 routes between PE routers?

Accepted Answer

MP-BGP. MP-BGP is used to carry VPNv4 routes between PE routers. OSPF, EIGRP, and IS-IS are IGPs and do not carry VPNv4 routes.

Answer

IS-IS

Answer

OSPF

Answer

EIGRP

Question 3

In a multicast environment, a PE router is not receiving multicast traffic from a source behind a CE. The PIM neighbors are established. The RP is reachable. What is the most likely issue?

Accepted Answer

The PE does not have the multicast VRF enabled. The most likely issue is that the PE router does not have the multicast VRF enabled. In a multicast VPN (MVPN) environment, even if PIM neighbors are established and the RP is reachable, the PE must have multicast routing explicitly enabled within the VRF using the 'ip multicast-routing vrf <name>' command. Without this, the PE will not process multicast traffic for that VRF, causing it to drop or ignore multicast packets from the source behind the CE.

Answer

The CE is not sending IGMP joins

Answer

The source address is not in the VRF

Answer

The RP is not configured in the VRF

Question 4

An SP network is running OSPFv3 for IPv6 and needs to support traffic engineering extensions for RSVP-TE. Which three statements about OSPFv3 TE extensions are true?

Accepted Answer

OSPFv3 TE uses TLV 1 (Router Address) in Opaque LSAs.. OSPFv3 uses Opaque LSA types 9, 10, and 11 for TE, with Type 10 carrying TE information link-state. OSPFv3 TE requires the OSPFv3 process to be configured for TE.

Answer

OSPFv3 TE requires the use of wide metrics.

Answer

OSPFv3 TE only supports point-to-point links.

Question 5

A service provider is implementing Multicast VPN (MVPN) in an MPLS backbone. They use Rosen GRE (draft-rosen) for multicast transport. What is the primary limitation of Rosen GRE compared to mLDP-based MVPN?

Accepted Answer

All multicast traffic is sent to every PE in the VPN, even if no receiver exists.. In Rosen GRE (draft-rosen) MVPN, a default MDT (Multicast Distribution Tree) is built using a shared PIM-SM group across all PEs in the VPN. All multicast traffic from any source in the VPN is encapsulated in GRE and sent to this default MDT group, meaning every PE receives the traffic regardless of whether it has any local receivers. This is the primary limitation because it wastes bandwidth and processing on PEs that do not need the traffic, unlike mLDP-based MVPN which builds trees only to PEs with receivers.

Answer

It requires full-mesh of GRE tunnels between all PEs.

Answer

It cannot use Source-Specific Multicast (SSM).

Answer

It does not support Protocol Independent Multicast (PIM).

Question 6

Refer to the exhibit. An engineer pushes this XML configuration via NETCONF, but the device rejects it with an error stating 'invalid policy-map structure'. What is the problem?

Accepted Answer

The class name must be defined in a class-map before being referenced in the policy-map. The error 'invalid policy-map structure' occurs because the policy-map references a class name that has not been defined in a class-map beforehand. In Cisco IOS, a class-map must exist before it can be used inside a policy-map; otherwise, the device rejects the configuration as structurally invalid.

Answer

The configuration is missing the class-default class

Answer

The YANG model does not support the 'police' keyword

Answer

The priority and police commands cannot coexist in the same class

Question 7

Which TWO are characteristics of Segment Routing?

Accepted Answer

Source routing capability. Segment Routing (SR) is a source-routing paradigm where the ingress node encodes a list of segments (instructions) into the packet header, guiding the packet through the network without intermediate routers needing to maintain per-flow state. Option B is correct because SR inherently provides source routing capability: the source node determines the path by stacking segment identifiers (SIDs), and transit nodes simply forward based on the top SID.

Answer

Uses only IPv6 data plane

Answer

Requires RSVP-like signaling for path setup

Answer

Requires a centralized SDN controller

Question 8

An SP engineer notices that BGP routes from a CE are not being installed in the VRF routing table, although the BGP session is established. The VRF configuration includes route-target import 100:1. The CE is sending routes with RT 100:1. What is the most likely cause?

Accepted Answer

The route is not matching any import map. Even though the BGP session is up and the CE is sending routes with the correct route-target (RT 100:1), the VRF may have an import map applied. An import map filters which received VPN routes are actually installed into the VRF routing table. If the route does not match the conditions defined in that import map, it will be accepted by BGP but not installed, which explains the symptom.

Answer

The BGP route is suppressed due to route update delay

Answer

The VRF name does not match

Answer

The RD is not configured

Question 9

Match each service provider architecture term to its description.

Accepted Answer

Provider Edge (PE) router: Connects to customer edge routers and provides MPLS VPN services.. The correct matches are: PE connects to customer edge, P is MPLS core, ASBR connects to other ASes. Common confusions: mistaking P for CE or confusing Route Reflector with ASBR.

Answer

Customer Edge (CE) router: Core router that forwards packets based on MPLS labels without customer awareness.

Answer

Route Reflector: Router that exchanges routing information with another autonomous system.

Question 10

You are a network engineer at a service provider that offers L3VPN services. A customer complains that their VPN traffic is intermittently dropping. The network uses OSPF as the IGP, LDP for label distribution, and MP-BGP for VPNv4 route exchange. The PE routers are connected to two core routers (P1 and P2) in a redundant design. Upon investigation, you find that the BGP next-hop for some VPN prefixes is set to the loopback interface of the remote PE, but the route to that loopback is sometimes unreachable due to a flapping link between P1 and P2. The IGP converges, but the BGP prefixes take longer to recover. What is the most likely cause of the intermittent drops?

Accepted Answer

BGP next-hop tracking is not enabled, causing BGP to rely on IGP convergence only. The intermittent drops occur because BGP next-hop tracking (NHT) is not enabled. Without NHT, BGP relies solely on IGP convergence to detect reachability changes for the BGP next-hop (the remote PE loopback). When the link between P1 and P2 flaps, OSPF converges quickly, but BGP does not immediately re-evaluate its next-hop reachability; it waits for the next BGP scan interval (default 60 seconds) or until a BGP update is received. This delay causes the VPN prefixes to remain installed with an unreachable next-hop, leading to traffic drops until BGP eventually withdraws or re-advertises the routes.

Answer

The OSPF network type is incorrectly set to point-to-point

Answer

The BGP timers are set too low, causing premature route withdrawal

Answer

The LDP session between the PEs is down