350-501 Services — All Questions With Answers

A service provider is deploying MPLS Layer 3 VPN and needs to ensure that BGP next-hop resolution works correctly for VPNv4 prefixes learned from a route reflector. The PE routers are directly connected to the RR via iBGP, and there is an IGP running within the MPLS core. Which condition must be met for the PE to install the VPNv4 prefix into its routing table?

Question 2hardmultiple choice

A service provider is designing a multicast solution for a Layer 3 VPN. They want to use MVPN with BGP signaling (draft-rosen). The PE routers are configured with VRF and multicast routing enabled. Which BGP address family must be enabled between PE routers to carry multicast routing information?

Question 3easymultiple choice

A network engineer is troubleshooting an MPLS TE tunnel that is not coming up. The tunnel is configured with a strict explicit path, and the path includes an interface that is currently down. Which action should the engineer take to allow the tunnel to use an alternative path?

Question 4mediummulti select

Which TWO statements about BGP FlowSpec (RFC 8955) are correct?

Question 5hardmulti select

Which THREE characteristics apply to the BGP-LS (BGP Link State) protocol?

Question 6hardmultiple choice

Refer to the exhibit. A service provider is applying this QoS policy on a PE-CE interface. The business customer complains that voice traffic (marked with DSCP EF) experiences drops during congestion. What is the likely cause?

Exhibit

interface GigabitEthernet0/0/0/0
 ipv4 address 10.1.1.1 255.255.255.252
 service-policy output QOS_POLICY
!
class-map match-any REALTIME
 match precedence 5
 match dscp ef
!
policy-map QOS_POLICY
 class REALTIME
  priority level 1
  police rate percent 10
 class class-default
  bandwidth remaining ratio 1

Question 7mediummultiple choice

Refer to the exhibit. A network engineer is troubleshooting MPLS forwarding for prefix 10.10.10.0/24. The router shows two entries. What does the 'Pop tag' in the outgoing tag indicate?

Exhibit

Router# show mpls forwarding-table 10.10.10.0/24
Local tag  Outgoing tag  Prefix         Outgoing interface  Bytes tag switched
16           Pop tag       10.10.10.0/24   GigabitEthernet0/0/0/0  345678
17           Untagged     10.10.10.0/24   GigabitEthernet0/0/0/1  123456

Question 8easymultiple choice

A service provider is implementing L2VPN using EoMPLS. The CE devices are connected to two different PE routers, and the PE routers are configured with xconnect under the attachment circuit. Which command is required on the PE routers to establish the pseudowire?

Question 9hardmultiple choice

A service provider is troubleshooting BGP route advertisement for a VPNv4 prefix. The PE router receives the prefix from the route reflector but does not install it in the VRF routing table. The BGP table shows the prefix as valid but not best. What is the most likely cause?

Question 10mediummultiple choice

A service provider is deploying MPLS Layer 3 VPNs and wants to ensure that customer traffic is not dropped when a PE-CE link fails. The CE router is using static routing. Which design should be implemented to provide fast convergence?

Question 11hardmultiple choice

Refer to the exhibit. A service provider is receiving BGP prefixes from a customer (AS 64512). The provider wants to tag all routes from that customer that match prefix 10.1.0.0/16 or more specific with community 65000:100, while not modifying other routes. After applying the configuration, which statement is true?

Exhibit

router bgp 65000
 neighbor 192.168.1.1 remote-as 64512
 address-family ipv4 unicast
  neighbor 192.168.1.1 route-map SET_COMMUNITY in
 !
route-map SET_COMMUNITY permit 10
 match ip address prefix-list MATCH_CUST_A
 set community 65000:100 additive
!
route-map SET_COMMUNITY deny 20
!
ip prefix-list MATCH_CUST_A seq 5 permit 10.1.0.0/16 le 24

Question 12easymulti select

A service provider is planning to offer L2VPN services using MPLS. Which TWO statements are true regarding Ethernet over MPLS (EoMPLS) and Virtual Private LAN Service (VPLS)?

Question 13hardmultiple choice

A service provider has a network with multiple PE routers providing MPLS L3VPN services. Customers are complaining that some remote sites are unreachable after a recent software upgrade on PE1. Upon investigation, you notice that PE1 is receiving BGP VPNv4 routes from the route reflector, but some routes are not being installed in the VRF routing table. PE1 is configured with BGP additional-path capability and has a route policy that selects only the best path. The VRF on PE1 has import and export route targets configured correctly. The missing routes have a higher local preference but are not selected due to a tie-break in BGP path selection. Which action should be taken to ensure that all valid routes are installed in the VRF?

Question 14hardmulti select

Which THREE of the following L3VPN services require the use of a dedicated control plane per VPN instance?

Question 15mediummultiple choice

Refer to the exhibit. CE1 is not receiving the VPNv4 route for the 192.168.1.0/24 subnet. What is the most likely cause?

Exhibit

Refer to the exhibit.

PE1 configuration snippet:
 router bgp 65000
  neighbor 10.0.0.2 remote-as 65000
  neighbor 10.0.0.2 update-source Loopback0
  !
  address-family vpnv4
   neighbor 10.0.0.2 activate
   neighbor 10.0.0.2 send-community extended
  !
  address-family ipv4 vrf CUSTOMER_A
   redistribute connected
  !

CE1 configuration snippet:
 interface GigabitEthernet0/0
  ip address 192.168.1.1 255.255.255.0
  no shutdown
 !
 router bgp 65001
  network 192.168.1.0 mask 255.255.255.0
  neighbor 10.1.1.1 remote-as 65000

Question 16easymultiple choice

A service provider is deploying a point-to-point Layer 2 VPN across an MPLS network using Ethernet over MPLS (EoMPLS) with Martini encapsulation. The customer requires transparent transport of VLAN tags (Q-in-Q) between two sites. The provider configures the attachment circuits on the PE routers as VLAN subinterfaces with dot1q encapsulation. After configuration, the customer reports that only untagged frames pass through the pseudowire; double-tagged frames are dropped at the egress PE. Which action resolves the issue?

Question 17mediumdrag order

Drag and drop the steps to configure a GRE tunnel on a Cisco router into the correct order.

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps

Order

1Step 1

2Step 2

3Step 3

4Step 4

5Step 5

Question 18mediummatching

Match each Segment Routing component to its function.

Drag a concept onto its matching description — or click a concept then click the description.

Concepts

Matches

Segment Identifier, an instruction in the SR header

Segment Routing Global Block of label values

Segment Routing over MPLS data plane

Topology-Independent Loop-Free Alternate for fast reroute

Path Computation Element Protocol for SR path computation

Question 19mediummultiple choice

A service provider is migrating its MPLS core from LDP to Segment Routing with MPLS data plane (SR-MPLS). The network currently uses TE tunnels with RSVP-TE for traffic engineering. Which technology can the provider use to continue performing traffic engineering after the migration without requiring RSVP-TE?

Question 20hardmultiple choice

A service provider is deploying EVPN-VPWS to replace legacy pseudowire connections for point-to-point Layer 2 services. They notice that MAC addresses learned from a CE device are not properly advertised to the remote PE. Which EVPN route type is responsible for advertising MAC address reachability information in a VPWS scenario?

Question 21easymultiple choice

A network engineer is configuring QoS on a Cisco ASR 9000 router to support multiple traffic classes. The policy must ensure that real-time traffic (EF) is not starved by high-volume bulk data (AF11). Which queuing strategy should be applied to the EF class to provide low latency and strict priority?

Question 22mediummultiple choice

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?

Question 23hardmultiple choice

An SP is designing a MPLS L3VPN service with BGP as the PE-CE routing protocol. They want to ensure that the CE router does not become a transit router between two sites. Which BGP feature should be configured on the PE to prevent the CE from advertising routes received from one site to another?

Question 24mediummultiple choice

A service provider is deploying LISP (Locator/ID Separation Protocol) to provide mobility and multihoming for customer endpoints. Which LISP component is responsible for maintaining the mapping between Endpoint Identifiers (EIDs) and Routing Locators (RLOCs) and for responding to Map-Request messages from ITRs?

Question 25easymultiple choice

A customer is connected to a service provider MPLS L3VPN network using BGP. The CE advertises a prefix 10.1.1.0/24 to the PE. On the PE, the customer's VRF route table shows the route with the next-hop set to the CE. When the PE receives a packet destined to 10.1.1.1, what label stack will the PE apply before forwarding the packet across the MPLS core?

Question 26mediummultiple choice

A service provider is implementing QoS policies on an access aggregation router. They want to shape traffic to a downstream DSLAM to 10 Mbps, but they do not want to exceed the shaping rate even if the line rate is higher. Which QoS tool should be used on the interface facing the DSLAM?

Question 27hardmultiple choice

An SP is troubleshooting an MPLS L2VPN VPLS network where MAC flapping is occurring between two PEs. Which mechanism in VPLS prevents loops and ensures that a broadcast frame from one PE is not reflected back to the originating PE?

Question 28mediummulti select

Which TWO of the following are characteristics of Segment Routing (SR-MPLS) compared to traditional LDP-based MPLS? (Select two.)

Question 29hardmulti select

Which THREE of the following are correct statements about EVPN-VXLAN in a data center fabric? (Select three.)

Question 30easymulti select

Which TWO of the following are services that can be offered using MPLS Layer 3 VPN (L3VPN) technology? (Select two.)

Question 31easymultiple choice

A service provider deploys MPLS L3VPN to connect multiple customer sites. Which VPN address family must be enabled on the PE routers to exchange customer IPv4 routes between PEs?

Question 32mediummultiple choice

A network engineer is troubleshooting slow BGP convergence after a link failure in an MPLS core. Which feature can be enabled on the PE routers to fast-failover traffic upon BGP next-hop unreachability?

Question 33hardmultiple choice

Refer to the exhibit. CE1 is unable to ping the loopback of a remote CE. Which configuration change is required on PE1 to enable communication?

Exhibit

Refer to the exhibit.
! On PE1
ip vrf CUSTOMER
 rd 100:1
 route-target export 100:100
 route-target import 100:100
!
! On PE1 BGP configuration
router bgp 65000
 neighbor 10.0.0.2 remote-as 65000
 neighbor 10.0.0.2 update-source Loopback0
 !
 address-family vpnv4
  neighbor 10.0.0.2 activate
  neighbor 10.0.0.2 send-community extended
 !
 address-family ipv4 vrf CUSTOMER
  neighbor 192.168.1.2 remote-as 65001
  neighbor 192.168.1.2 activate
!
! On CE1
interface GigabitEthernet0/0
 ip address 192.168.1.2 255.255.255.0
!
router bgp 65001
 neighbor 192.168.1.1 remote-as 65000
!

Question 34mediummultiple choice

A customer requires MPLS Layer 2 VPN connectivity between two sites using Pseudowire. Which control protocol is used to signal the pseudowire label?

Question 35easymultiple choice

Which technology allows a service provider to offer different classes of service over a single MPLS network?

Question 36hardmultiple choice

Study the full multicast explanation →

Refer to the exhibit. A network engineer applies this policy on the PE-CE link. What is the expected behavior for VoIP traffic matching the access list?

Exhibit

Refer to the exhibit.
! On PE router
ip access-list extended MATCH_VOIP
 permit udp any any range 16384 32767
!
class-map match-all VOIP
 match access-group name MATCH_VOIP
!
policy-map QOS_PE
 class VOIP
  priority percent 30
 class class-default
  fair-queue
!
interface GigabitEthernet0/0/0
 service-policy output QOS_PE
!

Question 37mediummultiple choice

During a multicast deployment, some receivers are not receiving the stream. The PIM neighbor table shows the upstream interface is correct. Which command would verify whether the multicast routing table has the correct outgoing interface list?

Question 38easymultiple choice

A service provider wants to provide Internet access to an MPLS L3VPN customer without leaking the Internet route into the VRF. Which feature allows the PE to forward traffic from the VRF to the global routing table?

Question 39hardmultiple choice

Refer to the exhibit. Which statement about this BGP configuration is true?

Exhibit

Refer to the exhibit.
! On PE router
router bgp 65000
 neighbor 10.1.1.1 remote-as 65000
 neighbor 10.1.1.1 update-source Loopback0
 !
 address-family vpnv4
  neighbor 10.1.1.1 activate
  neighbor 10.1.1.1 send-community extended
  neighbor 10.1.1.1 next-hop-self
 !
 address-family ipv4 vrf CUST_A
  redistribute ospf 1 vrf CUST_A
  no synchronization
 !
!

Question 40mediummulti select

Which TWO features are used to improve BGP convergence in an MPLS VPN environment?

Question 41hardmulti select

Which THREE components are required to deploy MPLS Layer 3 VPN?

Question 42mediummulti select

Which TWO statements about QoS policy propagation via BGP (QPPB) are correct?

Question 43easymultiple choice

Refer to the exhibit. Which prerequisite for MPLS L3VPN is missing on PE1?

Exhibit

Refer to the exhibit.
! On PE1
interface Loopback0
 ip address 10.0.0.1 255.255.255.255
!
interface GigabitEthernet0/0/0
 mpls ip
!
router ospf 1
 router-id 10.0.0.1
 network 10.0.0.0 0.255.255.255 area 0
 network 192.168.0.0 0.0.255.255 area 0
!
router ldp
!
router bgp 65000
 neighbor 10.0.0.2 remote-as 65000
 neighbor 10.0.0.2 update-source Loopback0
 !
 address-family vpnv4
  neighbor 10.0.0.2 activate
  neighbor 10.0.0.2 send-community extended
!

Question 44hardmultiple choice

Refer to the exhibit. Which statement is true regarding the forwarding entry for 10.2.2.0/24?

Exhibit

Refer to the exhibit.
! Output from show mpls forwarding-table
Local      Outgoing   Prefix           Bytes Label   Outgoing   Next Hop
Label      Label      or Tunnel Id     Switched      interface
16         Pop       10.1.1.0/24      0             Gi0/0/0    192.168.1.2
17         20         10.2.2.0/24      1000          Gi0/0/0    192.168.1.2
18         Untagged   10.3.3.0/24      500           Gi0/0/0    192.168.1.2
19         22         10.4.4.0/24      2000          Gi0/0/0    192.168.1.2

Question 45mediummultiple choice

Read the full VRF explanation →

A customer is experiencing packet loss during congestion on a link. The service provider wants to implement a QoS policy that drops less important traffic before more important traffic. Which queuing mechanism is best suited?

Question 46easymultiple choice

A service provider is configuring VRF-lite between two CE routers connected to the same PE. The CE routers are in different VRFs. Which command allows the PE router to forward traffic between the VRFs?

Question 47mediummultiple choice

A service provider is deploying MPLS L3VPN and wants to ensure that routes from a specific customer VRF are only advertised to a specific remote PE. Which mechanism should be used?

Question 48hardmultiple choice

In a Segment Routing network with TI-LFA enabled, which mechanism prevents micro-loops during a link failure?

Question 49easymultiple choice

Study the full multicast explanation →

A service provider is implementing QoS on a PE router for customer traffic. Which tool should be used to classify traffic based on application layer information?

Question 50easymultiple choice

Which multicast RP model is recommended for large-scale networks to provide redundancy and load sharing?

Question 51mediummultiple choice

A service provider is migrating from LDP to Segment Routing. What is the correct order of operations to ensure uninterrupted MPLS forwarding?

Question 52hardmultiple choice

In EVPN multihoming with all-active mode, what is the purpose of the aliasing capability?

Question 53hardmultiple choice

A service provider is using LISP to provide host mobility. Which LISP component is responsible for storing the mapping of EID to RLOC?

Question 54mediummultiple choice

Refer to the exhibit. A PE router has this BGP configuration. The CE router is advertising a default route via eBGP. However, the PE is not installing the route in the VRF table. What is the most likely cause?

Exhibit

router bgp 65000
 neighbor 10.1.1.1 remote-as 65000
 neighbor 10.1.1.1 update-source Loopback0
 !
 address-family vpnv4
 neighbor 10.1.1.1 activate
 neighbor 10.1.1.1 send-community extended
 exit-address-family
 address-family ipv4 vrf CUSTOMER
 redistribute connected
 exit-address-family

Question 55easymulti select

A service provider is configuring BGP community propagation in an MPLS VPN network. Which two actions are necessary to ensure that communities are passed from CE to remote PE?

Question 56mediummulti select

Which two of the following are characteristics of MPLS Traffic Engineering that differentiate it from pure MPLS forwarding?

Question 57hardmulti select

Which three of the following are valid methods for protecting a pseudowire in an MPLS network?

Question 58hardmultiple choice

Review the full OSPF breakdown →

A service provider operates a Layer 2 MPLS VPN using VPLS. Recently, two new CE routers were added to the VPLS domain, but they cannot ping each other. The existing CEs can communicate. The network uses BGP autodiscovery and signaling. The new CEs are connected to different PEs. The 'show vfi status' command on the new PEs indicates the VFI is up but the pseudowire to the remote PE is down. The BGP session between the PEs is established and the L2VPN address family routes are exchanged. What is the most probable cause?

Question 59mediummultiple choice

A customer's MPLS L3VPN has two CE routers connected to two different PEs, but the PEs are not receiving the customer's routes from each other. The PE-CE routing protocol is OSPF. The PEs have the VRF configured with OSPF process, and the routes from CE are in the VRF routing table. The MP-BGP session between PEs is up and the VPNv4 address family is working. On the source PE, the routes show as not advertised to BGP. What is the likely issue?

Question 60easymultiple choice

A service provider is deploying IGMPv3 snooping on an MVPN network to optimize multicast forwarding. After configuration, multicast traffic is not reaching receivers. The source is sending to group 239.1.1.1. The PE router has received the IGMP report from the receiver, and the MDT is established. What is the most likely reason?

Question 61mediummulti select

Which THREE factors must be considered when deploying MPLS Layer 3 VPN services to ensure optimal scalability and convergence?

Question 62easymultiple choice

A service provider recently deployed MPLS L3VPN for a customer with four sites (Site1, Site2, Site3, Site4) connected to PE1, PE2, PE3, and PE4 respectively. All sites are in VRF CUST-A with route targets 100:1 import and 100:1 export on all PEs. The customer reports that Site4 cannot ping the loopback interface (10.1.1.1/32) of Site1, but Site2 and Site3 can reach it. The provider verifies that BGP sessions between all PEs and the route reflector are up and that VPNv4 routes are advertised. The VRF on PE4 shows the route 10.1.1.1/32 with next-hop 192.0.2.1 (PE1's loopback) but when Site4 initiates a ping, it fails. What should the provider check next?

Question 63hardmultiple choice

A large service provider is migrating its L2VPN services (VPWS and VPLS) to EVPN-based solutions to improve scalability and support multi-homing. During the rollout for a customer using VLAN-based EVPN for a data center interconnect, the operations team notices frequent MAC address flapping and broadcast storms on one of the attachment circuits connected to a PE router. The PE is configured for EVPN-MPLS with ESI multihoming using all-active mode. The customer has two PEs (PE1 and PE2) connected to the same CE via two separate Ethernet links. The MAC table on PE1 shows the same MAC address alternating between the local AC interface and the remote EVPN peers. What is the most likely cause and the correct action to resolve this issue?

Question 64easymulti select

Which two statements about MPLS Layer 3 VPN route target (RT) communities are correct?

Question 65mediummultiple choice