300-410 Layer 3 Technologies Practice Test 13 — 15 Questions

Question 1

A network engineer is configuring OSPF on a router that connects to a service provider via a WAN link. The provider requires that the link be treated as a point-to-point connection without DR/BDR election, and the OSPF network type must be explicitly set to achieve this. Which command should be applied to the interface?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

ip ospf network point-to-point. The requirement is to treat the WAN link as a point-to-point connection without DR/BDR election. The ip ospf network point-to-point command achieves this by setting the OSPF network type to point-to-point, which disables DR/BDR election and allows direct adjacency formation. This is the standard configuration for point-to-point WAN links in OSPF.

Answer

ip ospf network broadcast

Answer

ip ospf network point-to-multipoint

Answer

ip ospf network non-broadcast

Question 2

A network engineer is configuring OSPFv3 on a router that connects to an IPv6 network. The router must form an adjacency with a neighbor on the same segment, but the engineer notices that the router is not sending any OSPFv3 Hello packets. The interface is up, and IPv6 unicast routing is enabled globally. Which of the following is the most likely cause?

Accepted Answer

The OSPFv3 process is not enabled on the interface.. For OSPFv3 to operate on an interface, the interface must be explicitly enabled for OSPFv3 using the 'ipv6 ospf' command under interface configuration. Simply enabling IPv6 unicast routing and configuring an OSPFv3 process is not sufficient. Without interface enablement, no Hello packets are sent, and no adjacency can form. This is a common oversight when transitioning from OSPFv2, where network statements are used.

Answer

The interface is configured as passive.

Answer

The OSPFv3 network type is set to point-to-multipoint.

Answer

The OSPFv3 router ID is not configured.

Question 3

A network engineer is configuring OSPFv3 on a dual-stack router. The router must form an adjacency with a neighbor over a link that supports both IPv4 and IPv6. The interface is configured with 'ipv6 ospf 1 area 0' and the router ID is manually set to 10.1.1.1. After applying the configuration, the engineer notices that the OSPFv3 adjacency remains in EXSTART state. What is the most likely cause?

Accepted Answer

The IPv6 MTU on the interface does not match the neighbor's interface MTU.. The EXSTART state in OSPFv3 indicates that the routers have exchanged Hello packets and are attempting to negotiate the master/slave relationship for database description exchange. A mismatch in interface MTU prevents the successful exchange of database description packets, leaving the adjacency stuck in EXSTART. Ensuring consistent MTU on both sides resolves the issue.

Answer

The router ID is not unique in the OSPFv3 domain.

Answer

The OSPFv3 process is not configured with an IPv6 address family.

Answer

The neighbor router is using a different OSPFv3 process ID.

Question 4

A network engineer is configuring MPLS Layer 3 VPN on a Cisco router. The engineer wants to ensure that the PE router can forward VPN traffic to the correct CE router based on the route target. Which of the following is required on the PE router?

Accepted Answer

A VRF instance with a route distinguisher and route target configured.. MPLS L3VPN relies on VRFs to separate customer routing tables. Each VRF must have a route distinguisher to make prefixes unique and route targets to control import/export of routes. The PE router uses these to forward traffic to the correct CE. Without a VRF with RD and RT, the PE cannot maintain separate VPN routing or forward based on VPN membership.

Answer

A static route to the CE router with a next-hop of the CE interface.

Answer

A route reflector client configured for the VPNv4 address family.

Answer

An IGP configured with multiprotocol BGP extensions.

Question 5

A network engineer is configuring a static route on a Cisco IOS router to reach a remote network. The engineer wants the route to be used only if the primary path fails and to be removed from the routing table when the primary path is available. Which type of static route should be configured?

Accepted Answer

Floating static route. A floating static route is designed to be a backup by setting a higher administrative distance than the primary route. It remains inactive until the primary route is removed from the routing table, at which point it becomes active. This provides redundancy without manual intervention, exactly matching the scenario's requirement.

Answer

Default static route

Answer

Recursive static route

Answer

Directly connected static route

Question 6

A network administrator is troubleshooting a DMVPN Phase 3 deployment using mGRE and IPsec. Spoke-to-spoke communication is not working directly; traffic is flowing through the hub. The administrator verifies that NHRP registrations are successful and that the hub has a route to all spokes. Which two actions are required to enable direct spoke-to-spoke communication? (Choose two.)

Accepted Answer

Configure 'ip nhrp shortcut' on the spoke tunnel interfaces.. DMVPN Phase 3 requires 'ip nhrp redirect' on the hub and 'ip nhrp shortcut' on the spokes to enable direct spoke-to-spoke tunnels. The hub uses redirect to inform the originating spoke of a better path, and the spoke uses shortcut to act on that information and establish a direct tunnel to the destination spoke. Without both, traffic continues to flow through the hub.

Answer

Configure 'ip nhrp network-id' on all tunnel interfaces.

Answer

Configure 'ip nhrp shortcut' on the hub tunnel interface.

Answer

Configure 'ip nhrp map' entries for all remote spokes on each spoke.

Question 7

A network administrator is troubleshooting an EIGRP network where a router is not receiving all expected routes from a neighbor. The neighbor relationship is established, and the topology table shows only a subset of routes. Which EIGRP feature could be filtering the routes?

Accepted Answer

EIGRP route filtering using distribute-list. EIGRP distribute-lists can filter routes either inbound or outbound. An inbound distribute-list applied on the local router can prevent specific routes from entering the topology table, even though the neighbor adjacency is up. This is a common cause of missing routes when the neighbor relationship is healthy. The distribute-list can use ACLs, prefix-lists, or route-maps to match and filter routes.

Answer

EIGRP variance

Answer

EIGRP authentication mismatch

Answer

EIGRP stub routing

Question 8

An engineer is configuring a GRE tunnel between two Cisco routers. The tunnel source is a physical interface, and the tunnel destination is the remote router's physical interface. After configuration, the tunnel interface is up, but no traffic passes through it. The engineer verifies that the physical interfaces are up and IP connectivity exists between the tunnel endpoints. What is the most likely cause?

Accepted Answer

There is no route to the remote network through the tunnel.. A GRE tunnel can be up, but without a route directing traffic into the tunnel, no data will traverse it. The tunnel interface's up state only indicates that the tunnel source and destination are reachable and the tunnel is operational. Routing is still required to forward traffic. Therefore, the absence of a route to the remote network via the tunnel is the most likely cause.

Answer

The tunnel destination is not reachable.

Answer

The tunnel keepalive is misconfigured.

Answer

The tunnel interface is missing an IP address.

Question 9

Which command correctly configures a static route on a Cisco IOS router to reach the network 172.16.0.0/16 via the next-hop address 10.1.1.1?

Accepted Answer

ip route 172.16.0.0 255.255.0.0 10.1.1.1. The correct command is 'ip route 172.16.0.0 255.255.0.0 10.1.1.1'. It specifies the destination network with the proper subnet mask and the next-hop address. Cisco IOS requires the subnet mask in dotted-decimal format, not CIDR notation, and the next-hop address must be provided for a route via a next-hop.

Answer

ip route 172.16.0.0 255.255.0.0 interface GigabitEthernet0/0

Answer

ip route 172.16.0.0 255.255.255.0 10.1.1.1

Answer

ip route 172.16.0.0/16 10.1.1.1

Question 10

A network engineer is configuring MPLS Layer 3 VPN on a Cisco IOS XE router. The engineer needs to enable the provider edge (PE) router to exchange VPNv4 routes with another PE router. Which address family must be configured under the BGP routing process to achieve this?

Accepted Answer

address-family vpnv4 unicast. To exchange VPNv4 routes between PE routers in an MPLS L3VPN environment, the BGP process must be configured with the address-family vpnv4 unicast command. This enables the PE routers to exchange VPNv4 prefixes along with MPLS labels and route targets. The other address families do not support VPNv4 route exchange.

Answer

address-family ipv4 vrf

Answer

address-family ipv6 unicast

Answer

address-family ipv4 unicast

Question 11

A network engineer is implementing policy-based routing (PBR) on a Cisco router. The goal is to forward traffic from a specific subnet to a next-hop IP address that is not directly connected, but reachable via a recursive lookup. The engineer configures a route-map with 'set ip next-hop recursive <IP>'. However, traffic is not being forwarded as expected. Which of the following is the most likely reason?

Accepted Answer

The next-hop IP address is not resolvable via a route in the RIB.. For 'set ip next-hop recursive' to work, the specified next-hop address must be resolvable via a route in the routing table. If no such route exists, the recursive lookup fails, and the PBR policy is skipped. The router then uses the normal routing table. Therefore, the absence of a route to the next-hop is the most likely cause of the failure.

Answer

The 'set ip next-hop recursive' command is not supported in PBR.

Answer

The next-hop IP address is reachable via the default route only.

Answer

The route-map is not applied to the correct interface.

Question 12

A network engineer is configuring EIGRP on a Cisco router. The router has two paths to the same destination network with different metrics. The engineer wants to enable unequal-cost load balancing. Which command must be configured to allow EIGRP to use the higher-cost path?

Accepted Answer

variance 2. The 'variance' command is required to enable unequal-cost load balancing in EIGRP. It sets a multiplier that determines which feasible successor routes, with metrics higher than the successor, can be used. The higher-cost path must also be a feasible successor (satisfy the feasibility condition) to be considered. Once variance is set, EIGRP can install multiple paths with different metrics.

Answer

traffic-share balanced

Answer

metric weights 0 1 1 1 1 1

Answer

maximum-paths 2

Question 13

A network engineer is configuring OSPFv2 on a multiaccess segment. The engineer wants to ensure that the designated router (DR) election is deterministic and that a specific router becomes the DR. The router has the highest OSPF priority on the segment, but it is not becoming the DR. What could be the reason?

Accepted Answer

The router is not the first to be powered on, and a DR has already been elected.. OSPF DR election is non-preemptive. Once a DR is elected, it retains the role until it fails or the OSPF process restarts. Even if a router with a higher priority joins the segment later, it will not preempt the existing DR. Therefore, the most likely reason is that a DR was already elected before this router became active. To force a new election, the OSPF process must be restarted or the interfaces reset.

Answer

The router is configured with a higher OSPF priority but is not the DR because of a mismatch in OSPF network types.

Answer

The router's OSPF priority is set to 0.

Answer

The router's router ID is lower than another router's router ID.

Question 14

A network administrator is configuring OSPF on a Cisco router. The router is connected to two different OSPF areas: Area 0 and Area 1. The administrator wants to summarize routes from Area 1 into Area 0. Which command should be used on the Area Border Router (ABR) to accomplish this?

Accepted Answer

area 1 range 10.1.0.0 255.255.0.0. Inter-area route summarization in OSPF is performed on ABRs using the 'area range' command. The area specified is the source area from which routes are summarized. In this case, routes from Area 1 are summarized before being advertised into Area 0. This reduces the number of LSAs and routing entries, improving scalability. The other commands either summarize external routes or apply to the wrong area, and thus do not meet the requirement.

Answer

summary-address 10.1.0.0 255.255.0.0

Answer

ip summary-address ospf 1 10.1.0.0 255.255.0.0

Answer

area 0 range 10.1.0.0 255.255.0.0

Question 15

A network administrator is troubleshooting an OSPFv3 network. Router R1 is not forming an adjacency with Router R2 over a point-to-point link. The administrator verifies that the interfaces are up, IPv6 addresses are configured, and OSPFv3 is enabled on both interfaces. The output of 'show ipv6 ospf interface' on R1 shows that the interface is in the 'LOOPBACK' state. What is the most likely reason for this state?

Accepted Answer

There is a duplicate router ID on the network, and R1 has detected its own router ID in a hello packet from R2.. The LOOPBACK state on an OSPFv3 interface indicates that the router has received a hello packet containing its own router ID. This is a safeguard against duplicate router IDs. When two routers on the same link share the same router ID, they will not form an adjacency, and the interface will remain in LOOPBACK state. The administrator should check the router ID configuration on both routers and ensure they are unique.

Answer

The interface is configured as a passive interface under the OSPFv3 process.

Answer

The interface is configured as a loopback interface instead of a point-to-point interface.

Answer

The OSPFv3 process is not enabled on the interface, causing it to be placed in the LOOPBACK state.