300-410 Layer 3 Technologies Practice Test 12 — 15 Questions

Question 1

A network administrator is troubleshooting an EIGRP adjacency that is stuck in the ACTIVE state. The adjacency is between two routers, R1 and R2, on a point-to-point link. The administrator notices that R1 is sending queries but not receiving replies. Which of the following is the most likely cause?

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

Accepted Answer

A stuck-in-active condition is caused by a router not receiving replies to its queries, often due to a unidirectional link or a neighbor that is unable to respond.. EIGRP routers enter the ACTIVE state when they lose a route and must query neighbors for an alternative path. If a neighbor does not respond to queries, the route can become stuck-in-active. This is often due to unidirectional link failures, high CPU on the neighbor, or packet filters that allow hellos but block other EIGRP packets. The symptom of queries being sent but no replies received points directly to a communication issue in one direction.

Answer

The autonomous system number is misconfigured on R1.

Answer

An access list is blocking EIGRP multicast packets on R2's interface.

Answer

The K values for EIGRP metric calculation are mismatched between R1 and R2.

Question 2

A network administrator is troubleshooting an EIGRP adjacency that is stuck in the ACTIVE state. The adjacency is between two routers, R1 and R2, on a point-to-point link. The administrator notices that R1 is sending queries but not receiving replies. Which of the following is the most likely cause?

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

Accepted Answer

Verify that the spoke routers have a route to the other spokes' tunnel endpoints via the hub, and that NHRP resolution is working.. In DMVPN Phase 3, spoke-to-spoke communication relies on NHRP shortcut resolution. For this to work, spokes must have a route to the other spokes' NBMA addresses (typically via the hub) and NHRP must be able to resolve their IP addresses. If NHRP resolution fails or there is no route to the NBMA address, the shortcut tunnel is not built, and traffic continues via the hub. Thus, verifying NHRP resolution and routing is essential.

Answer

Ensure that the hub is configured with 'ip nhrp map multicast dynamic' and spokes with 'ip nhrp map multicast <hub>'.

Answer

Configure 'ip ospf network broadcast' on all tunnel interfaces.

Answer

Enable OSPF point-to-multipoint network type on all tunnel interfaces.

Question 3

A network administrator is troubleshooting an EIGRP adjacency that is stuck in the ACTIVE state. The adjacency is between two routers, R1 and R2, on a point-to-point link. The administrator notices that R1 is sending queries but not receiving replies. Which of the following is the most likely cause?

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

Accepted Answer

Configure the subnets keyword under the redistribute command.. The subnets keyword is necessary when redistributing routes into OSPF to include subnetted routes. Without it, only classful networks are redistributed, which is why the EIGRP routes are missing. The seed metric alone does not ensure subnetted routes are advertised. Metric-type and route maps are unrelated to this requirement.

Answer

Set the metric-type to 1 under the redistribute command.

Answer

Enable OSPF on the interface connecting to the EIGRP domain.

Answer

Configure a route map to match the EIGRP routes.

Question 4

A network engineer is configuring a static route on a Cisco IOS router. The engineer wants the route to be used only if the primary route fails. Which command should be used to configure a floating static route?

Accepted Answer

ip route 0.0.0.0 0.0.0.0 192.168.1.1 200. A floating static route is a static route with an administrative distance higher than the primary route, so it is only installed in the routing table when the primary route is unavailable. The command `ip route 0.0.0.0 0.0.0.0 192.168.1.1 200` sets the administrative distance to 200, making it less preferred than dynamic routes. This is the standard method to configure a floating static route.

Answer

ip route 0.0.0.0 0.0.0.0 192.168.1.1 track 1

Answer

ip route 0.0.0.0 0.0.0.0 192.168.1.1 name BACKUP

Answer

ip route 0.0.0.0 0.0.0.0 192.168.1.1 permanent

Question 5

A network engineer is configuring OSPF on a Cisco router. The router has two interfaces in Area 0: GigabitEthernet0/0 (10.1.1.1/24) and GigabitEthernet0/1 (10.2.2.1/24). The engineer wants to ensure that the router ID is always 10.1.1.1, regardless of interface status. Which command should be used?

Accepted Answer

router ospf 1 then router-id 10.1.1.1. The engineer needs a stable OSPF router ID that remains 10.1.1.1 regardless of interface status. The only way to guarantee this is to explicitly configure the router ID under the OSPF process using the 'router-id' command. Relying on interface IP addresses can lead to changes if interfaces are removed or shut down.

Answer

ospf router-id 10.1.1.1

Answer

router-id 10.1.1.1

Answer

ip ospf router-id 10.1.1.1

Question 6

A network technician is configuring a static route on a Cisco router to reach a remote network. The technician wants the route to be used only if the primary path fails. Which type of static route should be configured?

Accepted Answer

Floating static route. A floating static route uses a higher administrative distance to remain inactive until the primary route is lost. This allows it to serve as a backup. Default, recursive, and directly connected static routes do not provide this conditional failover behavior. The floating static route is the correct choice for a backup path.

Answer

Directly connected static route

Answer

Recursive static route

Answer

Default static route

Question 7

A network engineer is configuring OSPF on a Cisco router. The router has three interfaces in Area 0, and the engineer wants to ensure that the router does not become a Designated Router (DR) on any of these interfaces. Which command should be used on each interface?

Accepted Answer

ip ospf priority 0. OSPF DR/BDR election is influenced by interface priority. A priority of 0 makes a router ineligible to become DR or BDR. The other options either do not exist, change the network type unnecessarily, or increase the likelihood of becoming DR. Therefore, setting priority to 0 on each interface is the correct approach.

Answer

ip ospf priority 255

Answer

ip ospf network point-to-point

Answer

ip ospf dr-disable

Question 8

A network administrator is troubleshooting an OSPFv3 network. Router R1 is configured with the following:

ipv6 unicast-routing
interface GigabitEthernet0/0
 ipv6 address 2001:DB8:1::1/64
 ipv6 ospf 1 area 0
 ipv6 ospf network point-to-point
!
router ospf 1
 router-id 1.1.1.1
!

R1 is not forming an adjacency with R2, which is configured with:

interface GigabitEthernet0/0
 ipv6 address 2001:DB8:1::2/64
 ipv6 ospf 1 area 0
 ipv6 ospf network broadcast
!
router ospf 1
 router-id 2.2.2.2

What is the most likely reason for the adjacency failure?

Accepted Answer

The network type mismatch (point-to-point vs. broadcast) prevents the routers from forming an adjacency.. OSPF network types must be consistent on both ends of a link for an adjacency to form. R1 is configured with ipv6 ospf network point-to-point, while R2 uses broadcast. This mismatch leads to differing hello packet handling and prevents the adjacency. To resolve, configure both interfaces with the same network type, either point-to-point or broadcast.

Answer

The router-id must be the same on both routers for an adjacency to form.

Answer

OSPFv3 requires the use of link-local addresses for adjacency formation, and they are not configured.

Answer

OSPFv3 requires the router-id to be configured under the interface, not under the router ospf process.

Question 9

A network engineer is deploying MPLS Layer 3 VPNs. The engineer must ensure that the PE routers can forward VPN traffic correctly. The following configuration is applied on a PE router:

ip vrf CUSTOMER
 rd 65000:1
 route-target export 65000:1
 route-target import 65000:1
!
interface GigabitEthernet0/1
 ip vrf forwarding CUSTOMER
 ip address 192.168.1.1 255.255.255.0

After configuration, the engineer notices that the CE router cannot reach remote sites. The MPLS core is operational, and MP-BGP is configured. What is the most likely missing configuration?

Accepted Answer

The BGP process must be configured with address-family ipv4 vrf CUSTOMER and the necessary redistribution or network statements.. In MPLS L3 VPN, the PE router must have a BGP address-family ipv4 vrf for each VRF to exchange VPN routes with other PE routers. The VRF definition and interface assignment are necessary but not sufficient. Without the address-family configuration and route redistribution or network statements, the PE will not advertise the customer routes, and remote sites will be unreachable.

Answer

The route-target must be configured under the interface GigabitEthernet0/1.

Answer

The PE router must have a route distinguisher configured under the BGP process.

Answer

The PE router must have a loopback interface configured and used for BGP peering.

Question 10

A network administrator is configuring a GRE tunnel between two Cisco routers to transport IPv6 traffic over an IPv4-only core. The administrator enters the following configuration on Router A:

interface Tunnel0
 ipv6 address 2001:DB8:100::1/64
 tunnel source 10.1.1.1
 tunnel destination 10.2.2.2
 tunnel mode gre ipv6

However, the tunnel interface remains down. What is the most likely cause?

Accepted Answer

The physical interface providing the tunnel source address is not operational or there is no route to the tunnel destination.. A GRE tunnel interface will only come up if the tunnel source is operational and there is a route to the tunnel destination. In this scenario, the tunnel source is 10.1.1.1, which must be assigned to an up interface, and the router must have a route to 10.2.2.2. Without these conditions, the tunnel remains down regardless of the tunnel mode or IPv6 configuration.

Answer

The tunnel source and destination must be IPv6 addresses, not IPv4.

Answer

The tunnel mode should be gre ipv6, but it is incorrectly set to gre ipv4.

Answer

The tunnel interface requires an IPv4 address in addition to the IPv6 address to become operational.

Question 11

A network engineer is configuring OSPF on a router with three interfaces: GigabitEthernet0/0 (10.1.1.1/24), GigabitEthernet0/1 (10.2.2.1/24), and Loopback0 (192.168.1.1/24). The engineer wants to ensure that the router ID is 192.168.1.1 and that it remains stable even if the Loopback0 interface flaps. Which command should be applied?

Accepted Answer

router ospf 1
 router-id 192.168.1.1. The router-id command under the OSPF process explicitly sets the OSPF router ID and ensures it remains stable regardless of interface state. Dynamic selection could change if the loopback flaps, leading to OSPF adjacency resets. The other options either enable OSPF on an interface or advertise a network, which do not control the router ID.

Answer

interface GigabitEthernet0/0
 ip ospf priority 1

Answer

interface Loopback0
 ip ospf 1 area 0

Answer

router ospf 1
 network 192.168.1.0 0.0.0.255 area 0

Question 12

A network engineer is troubleshooting a DMVPN Phase 3 network using OSPF. Spoke routers are unable to form OSPF adjacencies with each other directly, even though they can reach the hub. The engineer wants to enable direct spoke-to-spoke communication. Which configuration is required on the hub?

Accepted Answer

ip nhrp redirect. In DMVPN Phase 3, the hub must have ip nhrp redirect to send redirect messages to spokes, enabling them to establish direct tunnels. Spokes require ip nhrp shortcut to act on those redirects. The other options are either configured on spokes or are basic NHRP settings not specific to enabling spoke-to-spoke communication.

Answer

ip nhrp shortcut

Answer

ip nhrp map multicast dynamic

Answer

ip nhrp network-id 1

Question 13

A network engineer is implementing policy-based routing (PBR) on a Cisco router. The goal is to route traffic from a specific subnet to a next-hop IP address that is not directly connected. Which configuration is required to achieve this?

Accepted Answer

A route map that matches the source subnet and sets the next-hop IP address, and a static route to the next-hop IP address.. PBR with 'set ip next-hop' requires that the next-hop IP address be reachable. If it is not directly connected, a static route must be present to resolve the next-hop. The other options either do not address the reachability requirement or use incorrect syntax.

Answer

A route map that matches the source subnet and sets the interface to the next-hop interface.

Answer

A route map that matches the source subnet and sets the default next-hop IP address.

Answer

A route map that matches the source subnet and sets the next-hop IP address.

Question 14

A network engineer at a branch office is configuring OSPFv3 on a dual-stack router. The router must form an adjacency with a neighboring router that is also running OSPFv3. The engineer notices that the neighbor relationship remains in EXSTART state. Which command should be used to verify the OSPFv3 interface parameters that could cause this issue?

Accepted Answer

show ipv6 ospf interface. The correct answer is the command that displays OSPFv3 interface parameters. EXSTART state issues in OSPFv3 are commonly caused by MTU mismatches or network type mismatches. The 'show ipv6 ospf interface' command provides these details, allowing the engineer to compare and correct the configuration. Other commands show neighbor status, database, or protocol summary but lack interface parameter details.

Answer

show ipv6 protocols

Answer

show ipv6 ospf neighbor

Answer

show ipv6 ospf database

Question 15

An engineer configures a Cisco IOS router with two static routes to the 10.10.0.0/16 network: one via 192.168.1.1 with administrative distance 1, and another via 192.168.2.1 with administrative distance 200. The route via 192.168.1.1 is installed in the routing table. Later, the interface to 192.168.1.1 goes down. Which statement describes the router's behavior?

Accepted Answer

The router immediately installs the route via 192.168.2.1 in the routing table.. The primary static route via 192.168.1.1 with administrative distance 1 is preferred. When its interface goes down, the route is removed. The floating static route via 192.168.2.1, with administrative distance 200, becomes the best available path and is installed. This provides redundancy without dynamic routing protocols.

Answer

The router removes both static routes and sends an ICMP redirect to the source.

Answer

The router keeps the route via 192.168.1.1 in the routing table but marks it as unreachable.

Answer

The router load-balances traffic between the two next hops because both are configured.