300-410 Layer 3 Technologies Practice Test 6 — 15 Questions

Question 1

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 and IPv6 addresses are configured correctly. Which two actions should the administrator take to resolve the issue? (Choose two.)

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

Accepted Answer

Verify that the OSPFv3 router ID is unique and configured.. OSPFv3 adjacency formation requires a valid and unique router ID, and matching network types on the interfaces. The process ID is locally significant and does not need to match. Priority values are irrelevant on point-to-point links. Area ID must match, but in this scenario, the most common oversights are router ID and network type mismatch. Ensuring these two are correct will resolve the adjacency issue.

Answer

Confirm that both routers have the same OSPFv3 priority value.

Answer

Ensure that the interfaces are configured with the same OSPFv3 process ID.

Answer

Verify that the OSPFv3 area ID is the same on both interfaces.

Question 2

A network engineer is configuring MPLS Layer 3 VPN on a Cisco IOS XR router. The engineer needs to verify that the VPNv4 route reflectors are correctly propagating VPNv4 prefixes. Which two commands would be most useful to confirm that the route reflectors are functioning as expected? (Choose two.)

Accepted Answer

show bgp vpnv4 unicast neighbors <neighbor-address> advertised-routes. To verify that VPNv4 route reflectors are propagating prefixes, you need to check both what the route reflector is sending to its clients and what it is receiving from its peers. The 'advertised-routes' command shows the routes sent to a neighbor, confirming reflection. The 'received-routes' command shows routes received from a neighbor, confirming that the route reflector is learning the prefixes it should reflect. Together, they provide a comprehensive view.

Answer

show bgp vpnv4 unicast route-reflector

Answer

show bgp vpnv4 unicast summary

Answer

show bgp vpnv4 unicast route-reflector-client

Question 3

A network technician is configuring a Cisco router for the first time. The router needs to forward packets to a remote network 172.16.1.0/24 via next-hop 10.0.0.2. Which command correctly configures a static route for this purpose?

Accepted Answer

ip route 172.16.1.0 255.255.255.0 10.0.0.2. The correct command for a basic static route is 'ip route destination_network subnet_mask next_hop'. This configures the router to forward packets for 172.16.1.0/24 to 10.0.0.2. The other options include unnecessary or invalid parameters that either cause syntax errors or add optional features not required by the scenario. The simplest correct form is the one without additional parameters.

Answer

ip route 172.16.1.0 255.255.255.0 10.0.0.2 name REMOTE

Answer

ip route 172.16.1.0 255.255.255.0 10.0.0.2 255.255.255.255

Answer

ip route 172.16.1.0 255.255.255.0 10.0.0.2 1

Question 4

A network engineer is configuring a DMVPN Phase 3 network with OSPF as the routing protocol. The hub router is configured with 'ip nhrp redirect' and spoke routers with 'ip nhrp shortcut'. The engineer notices that spoke-to-spoke traffic is still going through the hub. Which action should be taken to enable direct spoke-to-spoke communication?

Accepted Answer

Verify that the spokes have a route to the destination spoke's tunnel IP address via the hub.. In DMVPN Phase 3, spoke-to-spoke shortcuts rely on the hub sending NHRP redirects when it receives traffic from one spoke destined to another. For this to happen, the originating spoke must first send the traffic to the hub, which requires a route to the destination spoke's tunnel IP via the hub. Once the hub redirects, the spoke uses NHRP shortcut to resolve the destination's NBMA address and establish a direct tunnel. If the spoke lacks a route via the hub, it cannot initiate the process.

Answer

Change the OSPF network type to broadcast on all routers.

Answer

Ensure that OSPF next-hop is not changed by using 'ip next-hop-self' on the hub.

Answer

Configure 'ip nhrp map multicast dynamic' on the hub.

Question 5

A network engineer is implementing policy-based routing (PBR) on a Cisco router. The goal is to forward traffic from subnet 10.1.1.0/24 to next-hop 192.168.1.1, but only for HTTP traffic (TCP port 80). Other traffic should follow the normal routing table. Which configuration achieves this?

Accepted Answer

route-map PBR permit 10
 match ip address 101
 set ip next-hop 192.168.1.1
!
interface GigabitEthernet0/0
 ip policy route-map PBR
!
access-list 101 permit tcp 10.1.1.0 0.0.0.255 any eq 80. The correct configuration uses a route map that matches HTTP traffic from subnet 10.1.1.0/24 with an extended ACL (permit tcp 10.1.1.0 0.0.0.255 any eq 80) and sets the next-hop to 192.168.1.1. The route map is applied to the ingress interface with 'ip policy route-map'. Non-matching traffic falls through the route map (implicit deny) and is routed normally. The other options either match all traffic, match the wrong traffic, or reverse the source and destination in the ACL.

Answer

route-map PBR permit 10
 match ip address 101
 set ip next-hop 192.168.1.1
!
interface GigabitEthernet0/0
 ip policy route-map PBR
!
access-list 101 permit ip 10.1.1.0 0.0.0.255 any

Answer

route-map PBR permit 10
 match ip address 101
 set ip next-hop 192.168.1.1
!
interface GigabitEthernet0/0
 ip policy route-map PBR
!
access-list 101 permit tcp any 10.1.1.0 0.0.0.255 eq 80

Answer

route-map PBR permit 10
 match ip address 101
 set ip next-hop 192.168.1.1
!
interface GigabitEthernet0/0
 ip policy route-map PBR
!
access-list 101 deny tcp 10.1.1.0 0.0.0.255 any eq 80
access-list 101 permit ip any any

Question 6

A network engineer is implementing route redistribution between OSPF and EIGRP on a Cisco router. The engineer wants to redistribute EIGRP routes into OSPF and OSPF routes into EIGRP. Which two commands are required to accomplish this? (Choose two.)

Accepted Answer

Under router ospf, use 'redistribute eigrp 1 subnets'.. To redistribute EIGRP into OSPF, the command 'redistribute eigrp 1 subnets' is used under the OSPF process, ensuring subnetted routes are included. To redistribute OSPF into EIGRP, the command 'redistribute ospf 1 metric ...' is used under the EIGRP process, providing the required seed metric. The other options contain invalid syntax or incorrect keywords for the respective protocols.

Answer

Under router ospf, use 'redistribute eigrp 1 metric 10000 100 255 1 1500'.

Answer

Under router eigrp, use 'redistribute ospf 1 subnets'.

Answer

Under router ospf, use 'default-metric 10000 100 255 1 1500'.

Question 7

A network engineer is troubleshooting a routing loop between two OSPF routers. The engineer notices that Router A is receiving Router B's Router-LSA with a sequence number that is lower than the one currently in its link-state database. What is the most likely cause of this issue?

Accepted Answer

Router B has been restarted and its LSA sequence number reset, causing Router A to reject the LSA.. In OSPF, each LSA has a sequence number that increments with each new instance. If a router restarts and loses its previous sequence number, it may originate an LSA with a lower sequence number. Neighbors that still have the higher sequence number will consider the new LSA as stale and may not update their databases, potentially causing routing loops or black holes. The correct answer identifies a router restart as the likely cause.

Answer

There is a mismatch in the OSPF hello and dead intervals on the link between Router A and Router B.

Answer

Router A has a corrupted link-state database and is incorrectly interpreting the sequence number.

Answer

Router B has a lower router ID and is attempting to become the Designated Router.

Question 8

A network engineer is deploying a DMVPN Phase 3 network with EIGRP as the routing protocol. The engineer wants to optimize traffic flow so that spoke-to-spoke traffic does not traverse the hub. Which configuration is required on the hub to enable spoke-to-spoke direct communication?

Accepted Answer

Configure 'ip nhrp redirect' on the hub's tunnel interface.. In DMVPN Phase 3, spoke-to-spoke direct communication is enabled by configuring 'ip nhrp redirect' on the hub. When a spoke sends traffic to another spoke via the hub, the hub forwards the packet and sends an NHRP redirect message back to the source spoke. The source spoke then initiates NHRP resolution to the destination spoke's NBMA address and establishes a direct tunnel. This avoids the need for the hub to advertise spoke routes with itself as next hop, which is characteristic of Phase 2.

Answer

Configure 'no ip split-horizon eigrp <AS>' on the hub's tunnel interface.

Answer

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

Answer

Configure 'ip next-hop-self eigrp <AS>' on the hub's tunnel interface.

Question 9

A network engineer is configuring OSPFv3 on a router. The engineer wants to enable OSPFv3 on an interface and ensure that the interface is part of area 0. Which command is required under interface configuration mode?

Accepted Answer

ipv6 ospf 1 area 0. To enable OSPFv3 on an interface and assign it to area 0, the correct interface-level command is 'ipv6 ospf 1 area 0'. This activates OSPFv3 for IPv6 on that interface. The global command 'ipv6 router ospf 1' only starts the process; the area must be configured on each interface. The command 'ip ospf' is for OSPFv2, and 'ospfv3' requires the address family keyword.

Answer

ospfv3 1 area 0

Answer

ip ospf 1 area 0

Answer

ipv6 router ospf 1 area 0

Question 10

A network engineer is configuring route redistribution between OSPF and EIGRP on a border router. The engineer wants to redistribute EIGRP routes into OSPF and set the OSPF metric to 20. Which command correctly accomplishes this?

Accepted Answer

redistribute eigrp 1 subnets metric 20. To redistribute EIGRP routes into OSPF and set the OSPF metric to 20, the command must include both the 'subnets' keyword to include subnetted routes and the 'metric 20' to set the cost. The correct command is 'redistribute eigrp 1 subnets metric 20' under OSPF configuration. The 'metric-type' keyword is for setting external route type, not the metric value.

Answer

redistribute eigrp 1 metric 20 subnets

Answer

redistribute eigrp 1 metric 20

Answer

redistribute eigrp 1 metric-type 20 subnets

Question 11

A network administrator is configuring EIGRP on a router and wants to ensure that only specific routes are advertised to a neighbor. The administrator uses a distribute-list with a route-map. Which of the following is a valid match condition in the route-map to filter routes based on their metric?

Accepted Answer

match metric 1000. EIGRP route-maps support the 'match metric' condition to filter routes based on their EIGRP metric. The command accepts a single metric value. To match a range, you would need to specify multiple 'match metric' statements or use a different filtering method. The valid command is 'match metric 1000', which matches routes with exactly that metric.

Answer

match metric range 1000 2000

Answer

match metric 1000 2000

Answer

match metric ge 1000 le 2000

Question 12

A network engineer is configuring OSPF on a router connected to a broadcast Ethernet segment shared with three other OSPF routers. The engineer notices that the router is not forming an adjacency with any of the other routers. The interface is up/up, and the OSPF network type is broadcast. Which of the following is the most likely cause?

Accepted Answer

The OSPF hello and dead timers are mismatched on the interface.. OSPF adjacencies on broadcast networks require matching hello and dead intervals. If timers are mismatched, hello packets are not accepted, and the adjacency remains in INIT or DOWN state. While other factors like duplicate router IDs, passive interfaces, or mask mismatches can also prevent adjacency, the most likely cause given the scenario is a timer mismatch. The engineer should verify timers with show ip ospf interface.

Answer

The interface is configured as passive.

Answer

The OSPF router ID is not unique in the area.

Answer

The subnet mask is mismatched on the interface.

Question 13

A network engineer is troubleshooting a BGP neighbor relationship that is stuck in Active state. The engineer verifies that IP connectivity is good and that the neighbor's IP address is reachable. What is a possible cause for this issue?

Accepted Answer

The BGP session is configured with a wrong update-source, causing TCP connection attempts to use an incorrect source IP.. A BGP session stuck in Active state means the router is trying to establish a TCP connection but not succeeding. Even if the neighbor's IP is reachable, an incorrect update-source can cause the TCP SYN to be sent from an IP that the neighbor cannot reach or does not expect, leading to connection failure. Other options like AS mismatch or missing router ID would not cause Active state; they would cause different failures or not affect TCP establishment.

Answer

The BGP router ID is not configured, and the router is using an interface IP address that is not reachable.

Answer

The neighbor is configured with a different autonomous system number than the local router.

Answer

The neighbor's IP address is not reachable, causing TCP connection attempts to fail.

Question 14

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 and IPv6 addresses are configured correctly. Which two actions should the administrator take to resolve the issue? (Choose two.)

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

Accepted Answer

R2's advertisement does not meet the feasibility condition because the reported distance is greater than the feasible distance.. The EIGRP feasibility condition is used to prevent routing loops. It requires that a neighbor's reported distance to a destination be less than the current feasible distance (the lowest known distance) for that destination. In this scenario, R2's reported distance is 1600, which exceeds the feasible distance of 1500, so the condition fails. Therefore, R2's route is not a feasible successor.

Answer

R2's advertisement meets the feasibility condition because the reported distance is less than the feasible distance.

Answer

R2's advertisement is considered a successor because it has the lowest reported distance.

Answer

R2's advertisement meets the feasibility condition and becomes a feasible successor.

Question 15

A network technician is configuring a static route on a Cisco IOS router. The goal is to forward all traffic destined for 192.168.1.0/24 to next-hop 10.0.0.1, but only if the next-hop is reachable via the directly connected interface GigabitEthernet0/0. Which command should be used?

Accepted Answer

ip route 192.168.1.0 255.255.255.0 GigabitEthernet0/0 10.0.0.1. When configuring a static route with both an outgoing interface and a next-hop IP, the router only installs the route if the interface is up and the next-hop is reachable via that interface. This is ideal for ensuring the route is only used when the next-hop is reachable through the specified interface. The correct syntax places the interface before the next-hop IP.

Answer

ip route 192.168.1.0 255.255.255.0 10.0.0.1 GigabitEthernet0/0

Answer

ip route 192.168.1.0 255.255.255.0 GigabitEthernet0/0

Answer

ip route 192.168.1.0 255.255.255.0 10.0.0.1