350-401 MPLS Practice Test 2 — 15 Questions

Question 1

A network engineer runs the following command on Router R7:

R7# show mpls ldp capabilities
    LDP Capabilities:
      Dynamic Capability: advertised
      Typed Wildcard FEC: advertised
      MTU Signaling: advertised
      P2MP: not advertised
      MPLS OAM: advertised
      LDP Graceful Restart: advertised
        Helper mode: enabled
        Restart mode: enabled
        Reconnect time: 120 sec
        Recovery time: 180 sec

Based on this output, which capability is NOT supported by this router?

Accepted Answer

P2MP (Point-to-Multipoint). The output lists capabilities that are advertised. P2MP (Point-to-Multipoint) is explicitly listed as 'not advertised', meaning it is not supported.

Answer

LDP Graceful Restart

Answer

MTU Signaling

Answer

Dynamic Capability

Question 2

A network engineer runs the following command on Router R8:

R8# show mpls ldp traffic
    LDP Traffic Statistics:
      Hellos sent: 5000, Hellos received: 4998
      Initialization messages sent: 2, received: 2
      Keepalive messages sent: 15000, received: 14995
      Label mapping messages sent: 100, received: 95
      Label withdraw messages sent: 5, received: 3
      Label release messages sent: 2, received: 1
      Label abort messages sent: 0, received: 0
      Notification messages sent: 1, received: 2
      Address messages sent: 10, received: 9
      Address withdraw messages sent: 1, received: 0

Based on this output, what is a likely issue?

Accepted Answer

There is a problem with label distribution because label withdraw messages are significantly higher than label release messages.. The statistics show a mismatch between sent and received messages for several types, especially label withdraw (5 sent, 3 received) and label release (2 sent, 1 received). This may indicate packet loss or a problem with the LDP session. However, the most notable discrepancy is in label mapping messages (100 sent, 95 received), suggesting some mapping messages were lost. But the question asks for a likely issue; the high number of label withdraws relative to releases could indicate instability.

Answer

The LDP session is experiencing packet loss because the number of hellos sent and received are not equal.

Answer

The router has sent 100 label mapping messages but received 95, indicating that 5 mapping messages were lost.

Answer

The router has sent 1 notification message and received 2, indicating errors in the LDP session.

Question 3

A network engineer runs the following command on Router R9:

R9# show mpls ldp bindings 10.9.9.0 255.255.255.0
  lib entry: 10.9.9.0/24, rev 10
        local binding:  label: 22
        remote binding: lsr: 10.9.9.1:0, label: 23
        remote binding: lsr: 10.9.9.2:0, label: 24
        remote binding: lsr: 10.9.9.3:0, label: 25

Based on this output, how many remote LDP peers have advertised a label for the prefix 10.9.9.0/24?

Accepted Answer

3. The output shows three remote bindings from different LSRs (10.9.9.1, 10.9.9.2, 10.9.9.3), each with a different label. So three remote peers have advertised labels.

Answer

1

Answer

2

Answer

4

Question 4

interface GigabitEthernet0/1
 ip address 10.1.1.1 255.255.255.0
 mpls ip
 mpls label protocol ldp
!
router ospf 1
 network 10.1.1.0 0.0.0.255 area 0
!
router ldp
 interface GigabitEthernet0/1
!
What is the effect of this configuration?

Accepted Answer

MPLS forwarding is enabled on GigabitEthernet0/1, and LDP will distribute labels for all routes in the routing table.. The configuration enables MPLS forwarding and LDP on the interface, with OSPF providing IGP reachability. LDP will distribute labels for prefixes learned via OSPF.

Answer

Only OSPF routes are labeled; static routes are excluded from LDP label distribution.

Answer

The 'mpls label protocol ldp' command is redundant because LDP is the default.

Answer

The configuration will fail because 'router ldp' requires an LDP router-id to be set.

Question 5

interface GigabitEthernet0/1
 ip address 10.1.1.1 255.255.255.0
 mpls ip
 mpls label protocol tdp
!
router ospf 1
 network 10.1.1.0 0.0.0.255 area 0
!
router ldp
 interface GigabitEthernet0/1
!
Which statement about this configuration is true?

Accepted Answer

The interface will use TDP for label distribution, ignoring the LDP configuration under router ldp.. The interface is configured with TDP (Cisco proprietary) while the router is configured for LDP (standard). This mismatch will prevent label exchange.

Answer

The router will use LDP because the global configuration overrides the interface command.

Answer

Both TDP and LDP will be used simultaneously on the interface.

Answer

The configuration will fail because TDP is not supported on this platform.

Question 6

ip vrf BLUE
 rd 100:1
 route-target export 100:1
 route-target import 100:1
!
interface GigabitEthernet0/1
 ip vrf forwarding BLUE
 ip address 10.1.1.1 255.255.255.0
!
router bgp 65000
 neighbor 192.168.1.1 remote-as 65000
 neighbor 192.168.1.1 update-source Loopback0
 address-family ipv4 vrf BLUE
  neighbor 192.168.1.1 activate
  network 10.1.1.0 mask 255.255.255.0
!
What is missing from this MPLS L3VPN configuration?

Accepted Answer

The BGP neighbor needs 'send-community extended' under the address-family to exchange VPN routes.. The configuration lacks the 'neighbor 192.168.1.1 send-community extended' command under the BGP address-family, which is required to exchange VPNv4 routes with extended communities.

Answer

The VRF definition is missing the 'mdt' command for multicast VPN.

Answer

The interface needs 'mpls ip' enabled for MPLS forwarding.

Answer

The BGP neighbor needs 'remote-as 65000' under the VRF address-family.

Question 7

interface GigabitEthernet0/1
 ip address 10.1.1.1 255.255.255.0
 mpls ip
!
interface GigabitEthernet0/2
 ip address 10.2.2.1 255.255.255.0
 mpls ip
!
router ospf 1
 network 10.0.0.0 0.255.255.255 area 0
!
router ldp
 interface GigabitEthernet0/1
 interface GigabitEthernet0/2
!
What is the effect of this configuration?

Accepted Answer

LDP will form adjacencies over both interfaces and distribute labels for all routes in the routing table.. LDP is enabled on both interfaces, but OSPF is configured with a wildcard that includes both subnets. LDP will form adjacencies and distribute labels for all OSPF routes.

Answer

Only OSPF routes will receive labels; static routes are ignored by LDP.

Answer

LDP will only form an adjacency on GigabitEthernet0/1 because it is the first interface configured.

Answer

The configuration will fail because OSPF and LDP are not compatible on the same interface.

Question 8

ip vrf RED
 rd 200:1
 route-target export 200:1
 route-target import 200:1
!
interface GigabitEthernet0/1
 ip vrf forwarding RED
 ip address 10.1.1.1 255.255.255.0
!
router bgp 65000
 neighbor 192.168.1.1 remote-as 65000
 neighbor 192.168.1.1 update-source Loopback0
 address-family vpnv4
  neighbor 192.168.1.1 activate
  neighbor 192.168.1.1 send-community extended
!
Which statement about this configuration is true?

Accepted Answer

The configuration is correct for MPLS L3VPN, but the VRF RED must also be configured under BGP with 'address-family ipv4 vrf RED'.. The BGP configuration includes 'send-community extended' under the VPNv4 address-family, which is required for MPLS L3VPN route exchange. However, the VRF RED is defined but not used in BGP.

Answer

The 'send-community extended' command is unnecessary because it is enabled by default.

Answer

The interface GigabitEthernet0/1 requires 'mpls ip' to forward MPLS packets.

Answer

The VRF RED will automatically import routes from the VPNv4 address-family without additional configuration.

Question 9

interface GigabitEthernet0/1
 ip address 10.1.1.1 255.255.255.0
 mpls ip
!
interface GigabitEthernet0/2
 ip address 10.2.2.1 255.255.255.0
 mpls ip
!
router ospf 1
 network 10.0.0.0 0.255.255.255 area 0
!
router ldp
 interface GigabitEthernet0/1
!
What is the effect of this configuration?

Accepted Answer

LDP will only form an adjacency over GigabitEthernet0/1; no label exchange occurs on GigabitEthernet0/2.. LDP is only enabled on GigabitEthernet0/1, not on GigabitEthernet0/2. This means LDP will not form an adjacency over GigabitEthernet0/2, and MPLS forwarding may be incomplete.

Answer

LDP will automatically enable on GigabitEthernet0/2 because MPLS is enabled there.

Answer

The configuration will fail because LDP must be enabled on all MPLS interfaces.

Answer

OSPF will automatically enable LDP on all interfaces in area 0.

Question 10

What is the default OSPF hello interval on an Ethernet link in Cisco IOS?

Accepted Answer

10 seconds. OSPF hello interval defaults to 10 seconds on broadcast and point-to-point networks (e.g., Ethernet).

Answer

30 seconds

Answer

40 seconds

Answer

5 seconds

Question 11

Which BGP attribute is preferred when it has the lowest value?

Accepted Answer

MED (Multi-Exit Discriminator). The MED (Multi-Exit Discriminator) attribute is used to influence inbound traffic to an AS, and the path with the lowest MED is preferred.

Answer

Local Preference

Answer

Weight

Answer

AS Path

Question 12

What is the maximum hop count for EIGRP?

Accepted Answer

100. EIGRP has a default maximum hop count of 100, which can be changed up to 255.

Answer

15

Answer

255

Answer

16

Question 13

Drag and drop the steps of MPLS LDP label distribution and FIB population into the correct order, from first to last.

Accepted Answer

Converge IGP (e.g., OSPF or IS-IS). First, IP routing must be operational so that the IGP converges. Then LDP is enabled on interfaces and forms neighbor relationships. LDP then assigns local labels to FECs and advertises them to neighbors. The remote label is received and installed in the LIB. Finally, the LFIB is populated with the best label bindings for forwarding.

Question 14

Drag and drop the steps of MPLS VPN (L3VPN) service provisioning into the correct order, from first to last.

Accepted Answer

Configure IGP and LDP on core interfaces. First, the provider edge (PE) router must have IGP and LDP running in the core. Then the VRF is defined with route distinguisher and import/export RTs. The customer edge (CE) interface is placed into the VRF. MP-BGP is configured between PEs to exchange VPNv4 routes. Finally, the CE routes are redistributed into the VRF and advertised via MP-BGP.

Question 15

Drag and drop the steps of MPLS traffic engineering (MPLS-TE) tunnel setup into the correct order, from first to last.

Accepted Answer

Configure IGP with TE extensions (OSPF TE or IS-IS TE). First, IGP must be configured with TE extensions (e.g., OSPF TE) to flood link attributes. Then MPLS-TE is enabled on interfaces. The headend router computes a path using CSPF based on constraints. The tunnel interface is configured with the destination and constraints. Finally, RSVP-TE signals the LSP and reserves bandwidth along the path.