300-410 Layer 3 Technologies Practice Test 5 — 15 Questions

Question 1

A network engineer is implementing MPLS Layer 3 VPNs. The customer edge (CE) router is running OSPF with the provider edge (PE) router. The engineer wants to prevent OSPF routes from the customer from being redistributed into the provider's OSPF domain and vice versa. Which mechanism should be used on the PE router?

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

Accepted Answer

OSPF distribute-list. The OSPF distribute-list is the mechanism to filter routes and prevent redistribution between customer and provider OSPF domains. It can be applied inbound or outbound on the PE router to control which routes are accepted or advertised. Other options like sham links, domain ID, and route tagging do not directly prevent redistribution without additional configuration.

Answer

OSPF sham links

Answer

OSPF route tagging

Answer

OSPF domain ID

Question 2

A network administrator is troubleshooting a DMVPN Phase 3 deployment using OSPF. Spoke routers are configured with 'ip nhrp redirect' on the hub and 'ip nhrp shortcut' on the spokes. Despite correct NHRP mappings, spoke-to-spoke traffic is still traversing the hub. Which OSPF configuration on the spokes is required to enable direct spoke-to-spoke communication?

Accepted Answer

The spokes must have 'ip ospf network broadcast' configured on the tunnel interface.. DMVPN Phase 3 allows spoke-to-spoke traffic to bypass the hub using NHRP shortcuts. For OSPF to support this, the tunnel interface on the spokes must use the broadcast network type. This enables the spokes to learn routes with next-hop addresses of other spokes, allowing direct communication. Without broadcast network type, OSPF may only use the hub as the next hop, defeating the purpose of Phase 3.

Answer

The spokes must be in the same OSPF area as the hub.

Answer

The spokes must have 'ip ospf network point-to-multipoint' configured on the tunnel interface.

Answer

The spokes must have 'ip ospf priority 0' configured on the tunnel interface.

Question 3

A network engineer is troubleshooting a DMVPN Phase 2 network where spoke-to-spoke traffic is not taking the direct path. The hub is configured with 'ip nhrp map multicast dynamic' and 'ip nhrp network-id 1'. The spokes are configured with 'ip nhrp map multicast <hub>' and 'ip nhrp network-id 1'. Which two additional configurations are required on the spokes to enable direct spoke-to-spoke communication? (Choose two.)

Accepted Answer

ip nhrp shortcut. In DMVPN Phase 2, spoke-to-spoke direct communication requires two key configurations on the spokes: 'ip nhrp shortcut' to enable the spoke to use NHRP to find a direct path, and a static NHRP map for each remote spoke's tunnel IP to its NBMA address. The hub must have 'ip nhrp redirect' to notify spokes of better paths, but that is on the hub. The network-id must match and is already correct.

Answer

ip nhrp registration no-unique

Answer

ip nhrp network-id 2

Answer

ip nhrp redirect

Question 4

A network administrator is troubleshooting an OSPFv3 network. Router R1 is configured with the command 'ipv6 router ospf 1' and interface GigabitEthernet0/0 is enabled with 'ipv6 ospf 1 area 0'. R1's neighbor R2 is stuck in EXSTART state. Which action is most likely to resolve the issue?

Accepted Answer

Ensure that the router ID is unique and manually configure it if necessary.. In OSPFv3, the router ID is a 32-bit value that must be unique. If a router lacks an IPv4 address, it cannot automatically derive a router ID, resulting in 0.0.0.0, which prevents adjacency formation. Neighbors may remain stuck in EXSTART. Manually configuring a unique router ID under the OSPFv3 process resolves the problem. Other options address unrelated issues such as MTU mismatch (not applicable to OSPFv3) or process ID, which is locally significant.

Answer

Verify that both routers have the same OSPFv3 process ID.

Answer

Configure the 'ipv6 ospf mtu-ignore' command on the interface.

Answer

Change the OSPFv3 network type to point-to-point on both routers.

Question 5

A network administrator is configuring a GRE tunnel between two routers. The tunnel interface is up, but no traffic is passing through it. What is a common reason for this issue?

Accepted Answer

The tunnel interface is not included in the routing protocol.. Even when a GRE tunnel interface is up, traffic will not pass unless routes direct traffic into the tunnel. A common mistake is to configure the tunnel but not include it in the routing protocol or add static routes. This results in the tunnel being up but unused. Verifying routing tables and ensuring the tunnel interface is advertised or has a static route is essential.

Answer

The tunnel mode is set to GRE.

Answer

The tunnel source and destination are not reachable.

Answer

The tunnel keepalives are disabled.

Question 6

A network engineer is configuring OSPF on a Cisco router. The router has three interfaces: GigabitEthernet0/0 (10.1.1.1/24), GigabitEthernet0/1 (10.1.2.1/24), and GigabitEthernet0/2 (10.1.3.1/24). The engineer wants to enable OSPF on all three interfaces but ensure that only GigabitEthernet0/0 and GigabitEthernet0/1 participate in OSPF area 0, while GigabitEthernet0/2 remains passive. Which configuration accomplishes this?

Accepted Answer

router ospf 1
 network 10.1.1.0 0.0.0.255 area 0
 network 10.1.2.0 0.0.0.255 area 0. The requirement is to enable OSPF on two specific interfaces and exclude the third entirely. Using network statements with exact subnet matches for the two interfaces ensures OSPF is enabled only on them. The third interface is not matched, so it does not run OSPF and its subnet is not advertised. Adding passive-interface is unnecessary because the interface is not enabled for OSPF in the first place.

Answer

router ospf 1
 network 10.1.0.0 0.0.255.255 area 0
 passive-interface default
 no passive-interface GigabitEthernet0/0
 no passive-interface GigabitEthernet0/1

Answer

router ospf 1
 network 10.1.1.0 0.0.0.255 area 0
 network 10.1.2.0 0.0.0.255 area 0
 passive-interface GigabitEthernet0/2

Answer

router ospf 1
 network 10.1.0.0 0.0.255.255 area 0
 passive-interface GigabitEthernet0/2

Question 7

A network engineer is configuring OSPF on a router that connects to a service provider via a WAN link. The engineer wants to prevent OSPF from forming an adjacency on the WAN interface while still advertising the connected subnet into OSPF. Which configuration achieves this?

Accepted Answer

router ospf 1; passive-interface <WAN interface>. The correct approach is to use the 'passive-interface' command under the OSPF routing process for the WAN interface. This stops OSPF hello packets from being sent or received on that interface, preventing adjacency formation, while still allowing the connected subnet to be advertised as a stub network into OSPF. Removing the network statement would stop advertising the subnet, and other commands like database-filter do not prevent adjacency.

Answer

ip ospf passive-interface on the WAN interface

Answer

interface <WAN interface>; ip ospf database-filter all out

Answer

router ospf 1; no network area

Question 8

A network engineer is configuring a GRE tunnel between two Cisco IOS routers to transport IPv6 traffic over an IPv4-only transit network. The engineer issues the command 'tunnel mode gre ipv6' on both routers. After applying the configuration, IPv6 pings across the tunnel fail. What is the most likely cause?

Accepted Answer

The 'tunnel mode gre ipv6' command is not supported; the correct command is 'tunnel mode gre ip' with IPv6 enabled on the tunnel interface.. The correct command to configure a GRE tunnel that transports IPv6 packets over an IPv4 network is 'tunnel mode gre ip'. This setting encapsulates the IPv6 payload within GRE and then within IPv4. The command 'tunnel mode gre ipv6' is invalid and not recognized by Cisco IOS, leading to configuration failure. After setting the correct mode, the engineer must assign an IPv6 address to the tunnel interface and enable IPv6 routing.

Answer

The 'tunnel mode gre ipv6' command is correct, but the tunnel interface requires an IPv6 address to be configured before it can pass traffic.

Answer

The tunnel mode command should be 'tunnel mode ipv6ip' to transport IPv6 over IPv4.

Answer

The tunnel source and destination addresses are not explicitly configured, so the tunnel interface remains down.

Question 9

A network engineer is configuring BGP on a Cisco IOS router. The router must establish an eBGP peering with a neighbor at 192.0.2.1 and advertise the network 10.1.1.0/24. The engineer wants to ensure that the BGP session uses the correct source IP address and that the network is advertised only if it exists in the routing table. Which two commands are required to meet these requirements? (Choose two.)

Accepted Answer

neighbor 192.0.2.1 update-source Loopback0. To establish an eBGP session, the neighbor remote-as command is mandatory. To ensure the session uses a specific source IP, the neighbor update-source command is used. While the network command advertises the prefix, the question asks for two commands to meet both the source IP and advertisement requirements; however, the network command is also needed for advertisement. The two commands that directly address the stated requirements are remote-as (for peering) and update-source (for source IP). The network command is necessary for advertisement but is not one of the two asked for in the context of ensuring source IP and peering.

Answer

redistribute connected

Answer

neighbor 192.0.2.1 ebgp-multihop 2

Answer

network 10.1.1.0 mask 255.255.255.0

Question 10

A network engineer is implementing policy-based routing (PBR) on a Cisco router. The goal is to forward HTTP traffic from a specific subnet to a next-hop address of 10.1.1.2, while all other traffic follows the routing table. Which configuration snippet correctly achieves this?

Accepted Answer

route-map PBR permit 10
 match ip address 101
 set ip next-hop 10.1.1.2
interface GigabitEthernet0/0
 ip policy route-map PBR. Policy-based routing uses route-maps to match traffic and set attributes like next-hop. The correct configuration defines an ACL to match HTTP traffic, a route-map that sets the next-hop, and applies the route-map to the interface with ip policy route-map. The set ip next-hop command forces matched traffic to the specified next-hop, while other traffic follows the routing table.

Answer

route-map PBR permit 10
 match ip address 101
 set ip default next-hop 10.1.1.2
interface GigabitEthernet0/0
 ip policy route-map PBR

Answer

route-map PBR permit 10
 match ip address 101
 set ip next-hop 10.1.1.2
interface GigabitEthernet0/0
 ip policy route-map PBR
ip route 0.0.0.0 0.0.0.0 GigabitEthernet0/1

Answer

route-map PBR permit 10
 match ip address 101
 set ip next-hop 10.1.1.2
interface GigabitEthernet0/0
 ip policy route-map PBR
access-list 101 permit tcp any any eq 80

Question 11

A network architect is designing a solution to connect multiple branch sites to a central headquarters using DMVPN. The design requires dynamic routing with OSPF over the DMVPN tunnels. Which two statements are correct regarding the configuration of OSPF on the DMVPN hub and spokes? (Choose two.)

Accepted Answer

The spoke routers should be configured with the 'ip ospf network point-to-multipoint' command on their tunnel interfaces.. For OSPF over DMVPN, using point-to-multipoint network type on both hub and spokes is a common and recommended practice. It eliminates DR/BDR elections, simplifies configuration, and allows spokes to form adjacencies with the hub without requiring a full mesh. This approach is scalable and avoids the complexities of broadcast network type in a hub-and-spoke topology.

Answer

The hub router must be configured with 'ip ospf priority 0' to prevent it from becoming a DR.

Answer

The hub router must be configured as a DR for the DMVPN tunnel network.

Answer

The hub router must be configured with a lower OSPF priority than the spokes to ensure it becomes the DR.

Question 12

A network engineer is configuring VRF-lite on a Cisco IOS router to separate traffic for two customers. The router has two interfaces connected to Customer A and one interface connected to Customer B. The engineer must ensure that Customer A's traffic is isolated from Customer B's and that each customer can run their own routing protocol. Which two configurations are required to achieve this? (Choose two.)

Accepted Answer

Create a VRF for each customer and assign the interfaces to the appropriate VRF.. VRF-lite achieves customer isolation by creating separate VRFs and assigning interfaces to them, and by running VRF-aware routing processes for each customer. These two steps ensure that each customer has its own routing table and can run independent routing protocols without leaking traffic. MPLS LDP, route targets, and global routing entries are not required and could undermine isolation.

Answer

Configure a global routing table entry for each customer to ensure reachability.

Answer

Enable MPLS LDP on the interfaces connecting to the customers to tag the traffic.

Answer

Configure route targets and route distinguishers for each VRF.

Question 13

A network engineer is configuring OSPFv3 on a router that connects to an IPv4-only OSPFv2 domain. The engineer wants to ensure that the OSPFv3 process uses the same router ID as the OSPFv2 process. Which command should be used?

Accepted Answer

No additional configuration is required; OSPFv3 automatically uses the OSPFv2 router ID if one is not configured.. OSPFv3 automatically inherits the router ID from OSPFv2 if no explicit router ID is configured for OSPFv3. This ensures that both protocols use the same identifier, which is important for consistent routing and troubleshooting. Manual configuration is unnecessary and can lead to mismatches if the OSPFv2 router ID changes. The automatic inheritance simplifies configuration and reduces errors.

Answer

router-id 10.1.1.1 under the router ospf configuration mode

Answer

router-id 10.1.1.1 under the IPv6 router ospf configuration mode

Answer

ipv6 router ospf 1, then router-id 10.1.1.1

Question 14

A network engineer is implementing policy-based routing (PBR) on a Cisco router. The goal is to route traffic from subnet 10.10.10.0/24 to a specific next-hop 192.168.2.1 for HTTP traffic (TCP port 80), while all other traffic follows the normal routing table. Which configuration sequence is required on the router's ingress interface?

Accepted Answer

Create a route-map that matches HTTP traffic and sets the next-hop to 192.168.2.1, then apply it with 'ip policy route-map' on the interface.. Policy-based routing is implemented using route-maps that define match conditions and set actions. To route only HTTP traffic from a specific subnet to a next-hop, the route-map must match the source subnet and destination port 80, then set the next-hop. Applying it with 'ip policy route-map' on the ingress interface ensures that only matching packets are policy-routed, while others follow the routing table. The other options either filter traffic without routing changes or apply policies too broadly.

Answer

Create an access-list that permits HTTP traffic, then apply it with 'ip access-group' on the interface.

Answer

Enable 'ip policy route-map' on the interface and configure a route-map that matches all traffic and sets the next-hop to 192.168.2.1.

Answer

Configure a static route for 10.10.10.0/24 pointing to 192.168.2.1 and enable 'ip route-cache policy' on the interface.

Question 15

A network administrator is troubleshooting an EIGRP adjacency issue between two routers, R1 and R2. The routers are directly connected via a GigabitEthernet link. R1's configuration includes 'eigrp router-id 1.1.1.1' and 'network 10.0.0.0'. R2's configuration includes 'eigrp router-id 2.2.2.2' and 'network 10.0.0.0'. The administrator notices that the adjacency is stuck in EXSTART state. Which of the following is the most likely cause?

Accepted Answer

The router IDs are not unique or are incorrectly configured.. In EIGRP, the EXSTART state is part of the neighbor adjacency formation process where routers negotiate master/slave roles for database exchange. A mismatch in interface MTU sizes can cause the adjacency to remain in EXSTART because large EIGRP update packets may be dropped by the router with the smaller MTU, preventing the exchange from completing. The router IDs in the scenario are unique, and AS/K-value mismatches would prevent adjacency earlier. Therefore, MTU mismatch is the most likely cause.

Answer

The EIGRP autonomous system numbers are mismatched.

Answer

The interface MTU sizes are mismatched.

Answer

The K-values are mismatched.