300-410 Practice Test 33 — 15 Questions

Question 1

A network engineer runs the following command on Router R1:

R1# show ipv6 interface tunnel 0
Tunnel0 is up, line protocol is up
  IPv6 is enabled, link-local address is FE80::1
  Global unicast address(es):
    2001:DB8:2::1, subnet is 2001:DB8:2::/64
  Joined group address(es):
    FF02::1
    FF02::2
  ICMP redirects are enabled
  ICMP unreachables are enabled
  ND DAD is enabled, number of DAD attempts: 1
  ND reachable time is 30000 milliseconds
  IPv6 uRPF: loose mode (allow default route)

Based on this output, what is the uRPF configuration on this interface?

Accepted Answer

uRPF is enabled in loose mode. The output explicitly shows 'IPv6 uRPF: loose mode (allow default route)', which confirms that unicast Reverse Path Forwarding (uRPF) is enabled in loose mode. In loose mode, the router checks that the source address of an incoming packet has a matching entry in the routing table, but it does not require the incoming interface to match the best return path. This is distinct from strict mode, which requires both a routing table entry and that the incoming interface is the same as the outgoing interface for the return route.

Answer

uRPF is disabled

Answer

uRPF is enabled in strict mode

Answer

uRPF is enabled but only for IPv4

Question 2

Which TWO statements about MPLS label imposition (push) are true? (Choose TWO.)

Accepted Answer

Label imposition occurs at the ingress LSR.. Label imposition occurs at the ingress LSR, which pushes a label onto an unlabeled IP packet. The label is based on the FEC (Forwarding Equivalence Class) derived from the IP destination. The egress LSR pops the label, not imposes it.

Answer

Label imposition occurs at the egress LSR.

Answer

The imposed label is always the top label in a label stack.

Answer

Label imposition is performed using the 'tag-switching' command.

Question 3

A network engineer runs the following command on Router R8:

R8# show logging | include %LDP-5-NBRCHG

*Mar  1 00:01:10.123: %LDP-5-NBRCHG: LDP Neighbor 10.0.0.2:0 (1) is UP
*Mar  1 00:02:20.456: %LDP-5-NBRCHG: LDP Neighbor 10.0.0.2:0 (1) is DOWN
*Mar  1 00:03:30.789: %LDP-5-NBRCHG: LDP Neighbor 10.0.0.2:0 (1) is UP
*Mar  1 00:04:40.012: %LDP-5-NBRCHG: LDP Neighbor 10.0.0.2:0 (1) is DOWN

Based on this output, what is the most likely problem?

Accepted Answer

The LDP session is flapping due to an unstable IGP route to 10.0.0.2.. The log shows the LDP neighbor 10.0.0.2 repeatedly going UP and DOWN, which indicates a flapping LDP session. The most likely cause is an unstable IGP route to the neighbor's loopback address (used for LDP router ID), causing the LDP session to reset. LDP relies on the underlying IGP for reachability; if the route flaps, the LDP session will flap.

Answer

The MPLS label space is exhausted.

Answer

The router has a mismatched LDP router ID.

Answer

The LDP hello interval is set too high, causing slow detection.

Question 4

An engineer redistributes OSPF routes into EIGRP. The OSPF routes have a metric of 20. After redistribution, the EIGRP topology table shows the routes but they are not installed in the routing table. The 'show ip eigrp topology' shows the route in active state. Which is the most likely explanation?

Accepted Answer

The EIGRP neighbor is stuck-in-active because a query was sent but no reply was received due to a unidirectional link.. A route stuck in EIGRP active state means the router sent a query for that destination and is waiting for a reply; if a reply never arrives (often due to a unidirectional link or broken neighbor adjacency), the route remains active and is never installed in the routing table. The redistribution itself succeeded — the route is in the topology table — so the problem is with query/reply propagation, not with metrics or route-maps.

Answer

The 'default-metric' command was not configured, so the routes are redistributed with an infinite metric.

Answer

The OSPF routes are external type 2, which are not redistributed by default.

Answer

The 'route-map' used for redistribution has a 'match ip address' that does not match the OSPF routes.

Question 5

A network engineer runs the following command on Router R1:

R1# show ip ospf database summary 172.16.0.0

OSPF Router with ID (1.1.1.1) (Process ID 1)

Summary Net Link States (Area 0)

LS age: 100
  Options: (No TOS-capability, DC)
  LS Type: Summary Links(Network)
  Link State ID: 172.16.0.0 (Summary Network Number)
  Advertising Router: 2.2.2.2
  LS Seq Number: 80000001
  Checksum: 0x1234
  Length: 28
  Network Mask: /20
  TOS: 0  Metric: 10

Based on this output, what does this LSA represent?

Accepted Answer

It is a summary route for 172.16.0.0/20 advertised by ABR 2.2.2.2.. This is a Type 3 Summary LSA, which is used to advertise inter-area routes. The Advertising Router is 2.2.2.2, an ABR.

Answer

It is a router LSA from R1.

Answer

It is an external route from ASBR.

Answer

It is a network LSA for the 172.16.0.0 network.

Question 6

A network engineer runs the following command on router R3:

R3# show monitor session 5
Session 5
---------
Type : ERSPAN Destination Session
Status : Admin Enabled
Source IP : 10.0.0.2
Destination Ports : Gi0/1
    Encapsulation : Native
    Ingress : Disabled
ERSPAN ID : 100

Based on this output, which statement is correct?

Accepted Answer

The ERSPAN destination session receives traffic from source IP 10.0.0.2 and sends it to Gi0/1.. The output shows 'Type: ERSPAN Destination Session' with 'Source IP: 10.0.0.2' and 'Destination Ports: Gi0/1'. In an ERSPAN destination session, the switch receives GRE-encapsulated mirrored traffic from the source IP (the ERSPAN source session's origin) and forwards the decapsulated traffic out the destination port Gi0/1. Therefore, the session receives traffic from 10.0.0.2 and sends it to Gi0/1.

Answer

The ERSPAN destination session sends traffic to source IP 10.0.0.2.

Answer

The session is an RSPAN destination session because it uses a destination port.

Answer

The session is misconfigured because the destination port has ingress disabled.

Question 7

A network engineer runs the following command on Router R1:

R1# show mpls l2transport vc 100 detail
Local interface: Gi0/0/0 up, line protocol up
  Destination: 10.0.0.2, VC ID: 100, VC status: down
  Last error: No remote LDP session

Based on this output, what is the most likely cause of the VC being down?

Accepted Answer

The LDP session between the routers is not established.. The output explicitly states 'Last error: No remote LDP session,' which means the local router cannot establish an LDP session with the remote PE (10.0.0.2). In AToM (Any Transport over MPLS) / L2VPN pseudowire setups, the VC status depends on an operational LDP session between the two PEs to exchange VC labels. Without that LDP session, the VC cannot come up regardless of interface or VC ID configuration.

Answer

The local interface Gi0/0/0 is administratively down.

Answer

The remote router 10.0.0.2 is not reachable via IP.

Answer

The VC ID 100 is mismatched on the remote router.

Question 8

An engineer configures unicast Reverse Path Forwarding (uRPF) in strict mode on an interface. Traffic from a legitimate source IP is being dropped. The network has asymmetric routing. Which is the most likely explanation?

Accepted Answer

The router receives the packet on an interface that is not the best return path to the source IP, causing strict uRPF to drop it.. Strict uRPF verifies that the source IP of an incoming packet is reachable via the exact interface on which the packet arrived. In asymmetric routing, the return path to the source may use a different interface, causing the router to see the incoming interface as not matching the best return path in the FIB. This mismatch triggers a drop, even though the source IP is legitimate and reachable.

Answer

The source IP is not in the routing table at all.

Answer

The uRPF configuration is missing the 'allow-default' option.

Answer

The router is using loose mode instead of strict mode.

Question 9

Which TWO configuration steps are required to enable VRF-Lite on a Cisco IOS-XE router for a customer with two separate routing domains? (Choose TWO.)

Accepted Answer

Create the VRF using the 'vrf definition ' command and assign a route distinguisher with the 'rd' command.. The two essential steps are: creating the VRF with a route distinguisher using 'vrf definition ' and 'rd ', and assigning interfaces to the VRF with 'vrf forwarding ' under the interface. The other options are incorrect: 'ip vrf ' is legacy syntax but still works; however, 'rd' is required. Route targets are for MPLS VPN, not VRF-Lite. Import/export maps are optional. BGP is not mandatory.

Answer

Configure route target import/export statements under the VRF.

Answer

Apply an import map and export map to control route redistribution.

Answer

Enable BGP to exchange routes between VRFs.

Question 10

A network engineer runs the following command on Router R1:

R1# show dmvpn
Legend: Attrb -> S: Static, D: Dynamic, I: Incomplete
        N: NATed, L: Local, X: No Socket
        # Ent -> Number of NHRP entries with same NBMA peer
        NHS Status: E => Expecting Replies, R => Responding, W => Waiting
        UpDn Time -> Up or Down Time for a Tunnel
==========================================================================
Interface: Tunnel0, IPv4 NHRP Details
Type:Hub, NHRP Peers:2,

# Ent  Peer NBMA Addr Peer Tunnel Add State  UpDn Tm Attrb
 ----- --------------- --------------- ----- -------- -----
     1 192.168.1.2     10.0.0.2        UP    00:15:30 D
     1 192.168.1.3     10.0.0.3        UP    00:10:20 D

Based on this output, what is the role of Router R1?

Accepted Answer

Router R1 is a DMVPN hub.. The 'show dmvpn' output shows 'Type:Hub' for Tunnel0, which explicitly identifies Router R1 as the DMVPN hub. Additionally, R1 has two NHRP peers (the spokes) with dynamic (D) attributes, which is the expected view from the hub. A spoke would show 'Type:Spoke' and typically list the hub as its peer.

Answer

Router R1 is a DMVPN spoke.

Answer

Router R1 is a DMVPN server.

Answer

Router R1 is a DMVPN client.

Question 11

MPLS network: LDP neighbors are down between R1 and R2. R1 shows: show mpls ldp neighbor includes nothing. R2 has: interface GigabitEthernet0/0, mpls ip, but R1 has no mpls ip on its interface. What is the root cause?

Accepted Answer

R1's interface lacks the mpls ip command, preventing LDP hello transmission.. The root cause is that R1's interface is missing the 'mpls ip' command. This command is required on each interface to enable MPLS forwarding and to send LDP hello messages (UDP port 646) to neighbors. Without it, R1 cannot discover R2 as an LDP neighbor, so the LDP session never forms, and 'show mpls ldp neighbor' returns nothing on R1.

Answer

R1 and R2 are in different MPLS domains.

Answer

LDP router IDs are not reachable.

Answer

The label distribution protocol is set to TDP instead of LDP.

Question 12

In MPLS L3VPN, what is the default behavior when a PE router receives a VPNv4 route with a Route Target that does not match any import RT on any VRF?

Accepted Answer

The route is stored in the BGP table but not installed in any VRF routing table.. In MPLS L3VPN, a PE router receives VPNv4 routes via MP-BGP and evaluates the Route Target (RT) extended community against the import RTs configured on each VRF. If no VRF has a matching import RT, the route remains in the BGP table (the VPNv4 RIB) but is not imported into any VRF routing table, so it is not used for forwarding. This is the default behavior: the route is not discarded, but it is also not installed anywhere.

Answer

The route is discarded and not stored in the BGP table.

Answer

The route is installed in the global routing table.

Answer

The route is advertised to all other PEs.

Question 13

A network engineer is troubleshooting an IPv6 over IPv4 tunnel that is used to connect two remote sites. The tunnel is configured with a tunnel source that is a loopback interface. The tunnel is up, but the engineer cannot ping the remote tunnel endpoint IPv6 address. The engineer checks the routing table and sees a route to the remote loopback's IPv4 address via a default route. What is the most likely cause?

Accepted Answer

The remote router does not have a route to the loopback network used as the tunnel source; it only has a default route that may not cover that prefix.. The tunnel is up, but the engineer cannot ping the remote tunnel endpoint IPv6 address because the remote router lacks a route back to the loopback network used as the tunnel source. The remote router only has a default route, which may not cover the specific prefix of the local loopback, causing return traffic to be dropped. For IPv6 over IPv4 tunnels, the tunnel source and destination must be reachable via unicast routing; a missing or insufficient route (like a default that doesn't match) breaks bidirectional communication.

Answer

The tunnel destination is configured with the loopback address of the remote router, but the remote router's tunnel source is a different interface.

Answer

The tunnel interface is missing the 'tunnel mode ipv6ip' command.

Answer

The IPv6 address on the tunnel interface is not in the same subnet as the remote tunnel IPv6 address.

Question 14

A network engineer runs the following command on Router R1:

R1# show route-map
route-map FILTER_OSPF, permit, sequence 10
  Match clauses:
    ip address prefix-list OSPF_ROUTES
  Set clauses:
  Policy routing matches: 0 packets, 0 bytes
route-map FILTER_OSPF, deny, sequence 20
  Match clauses:
  Set clauses:
  Policy routing matches: 0 packets, 0 bytes

Based on this output, which statement is correct?

Accepted Answer

The route-map will permit all routes that match the prefix-list OSPF_ROUTES and deny all others.. The route-map FILTER_OSPF has a permit sequence 10 matching prefix-list OSPF_ROUTES, followed by a deny sequence 20 with no match clause. In Cisco IOS, a route-map sequence with no match clause matches everything, so sequence 20 acts as an implicit deny-all for any route not matched by sequence 10. Therefore, routes matching OSPF_ROUTES are permitted, and all others are denied.

Answer

The route-map will permit all routes because sequence 20 has no match clause.

Answer

The route-map is used for policy-based routing and has matched 0 packets.

Answer

The route-map will deny only routes matching the prefix-list OSPF_ROUTES.

Question 15

Router R6 is configured to send SNMP inform requests to the NMS at 192.168.1.1. Configuration: snmp-server host 192.168.1.1 informs version 2c public, snmp-server enable traps. The NMS receives no informs. R6's show snmp statistics shows InformRequestsSent: 0, and show snmp pending shows no pending. The NMS can poll R6 successfully. The network has a firewall between R6 and the NMS that allows UDP 162. What is the root cause?

Accepted Answer

The 'snmp-server host' command for informs requires the 'informs' keyword to be placed correctly, but the router may not support informs with v2c; informs are only supported with SNMPv3.. SNMPv2c does not support informs; informs require SNMPv3 because they need acknowledgment (response) from the NMS, which is only defined in SNMPv3. The 'snmp-server host' command with the 'informs' keyword will be accepted syntactically on a router running v2c, but the router will never actually send informs because the underlying protocol does not support the acknowledgment mechanism. This explains why InformRequestsSent remains 0 and no pending informs exist, even though the NMS can be polled successfully.

Answer

The NMS is not configured to send SNMP responses to informs.

Answer

The firewall is blocking UDP 162 from the NMS to the router.

Answer

The router's SNMP agent is not enabled due to a missing 'snmp-server' command.