300-410 Layer 3 Technologies Practice Test 10 — 15 Questions

Question 1

A network engineer is configuring EIGRP named mode on a Cisco IOS XE router. The engineer wants to ensure that the router advertises a default route into the EIGRP domain only when a specific prefix (10.1.1.0/24) is present in the routing table. Which configuration accomplishes this?

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

Accepted Answer

Create a static default route to Null0, redistribute static routes into EIGRP, and use a route-map that matches 10.1.1.0/24 to control redistribution.. EIGRP does not have a native conditional default origination command like OSPF's `default-information originate`. Instead, you create a static default route, redistribute it, and use a route-map to match the presence of a specific prefix. The route-map can reference an ACL or prefix-list that matches 10.1.1.0/24, and the redistribute statement will only inject the default if that condition is true.

Answer

Under `address-family ipv4 unicast`, configure `topology base` then `default-information originate` with a route-map matching 10.1.1.0/24.

Answer

Use the `summary-address 0.0.0.0 0.0.0.0` command under the EIGRP address family to inject a default summary route conditionally.

Answer

Configure `network 0.0.0.0` under the EIGRP address family to advertise a default route automatically when any route exists.

Question 2

A network engineer is deploying DMVPN Phase 3 with EIGRP as the routing protocol. The hub router is configured with `ip nhrp redirect` and spoke routers with `ip nhrp shortcut`. Spokes successfully register with the hub and receive routes, but spoke-to-spoke traffic still traverses the hub instead of building direct tunnels. Which action should the engineer take to enable direct spoke-to-spoke tunnels?

Accepted Answer

Configure `no ip next-hop-self eigrp` on the hub for the tunnel interface.. DMVPN Phase 3 requires the hub to preserve the original next-hop when advertising routes to spokes. By default, EIGRP on the hub may set next-hop-self, causing spokes to use the hub for all destinations. Disabling next-hop-self with `no ip next-hop-self eigrp` allows the spoke to see the true next-hop and trigger NHRP resolution to build a direct tunnel, which is the essence of Phase 3 shortcuts.

Answer

Configure `ip nhrp network-id` with a matching value on all routers.

Answer

Enable `ip nhrp map multicast dynamic` on the hub tunnel interface.

Answer

Add `ip nhrp nhs` on the hub pointing to each spoke's tunnel address.

Question 3

A network engineer is troubleshooting an OSPFv2 network. Area 0 consists of four routers connected via a Frame Relay hub-and-spoke topology using physical interfaces. The hub router (R1) is configured with `ip ospf network non-broadcast`. The spoke routers (R2, R3, R4) are configured with `ip ospf network non-broadcast` as well. The engineer notices that R2, R3, and R4 form adjacencies with R1, but no adjacencies form between the spokes. Which configuration change is required to allow full adjacency among all routers?

Accepted Answer

Change the OSPF network type to point-to-multipoint on all routers.. In a Frame Relay hub-and-spoke topology with non-broadcast network type, OSPF treats the interfaces as non-broadcast multi-access (NBMA), requiring manual neighbor configuration and allowing only hub-to-spoke adjacencies because spokes cannot communicate directly. Changing to point-to-multipoint network type on all routers makes OSPF treat the hub as a collection of point-to-point links, using multicast hellos and allowing the hub to forward routing updates between spokes, thus enabling full adjacency among all routers.

Answer

Configure the hub router with `ip ospf network point-to-multipoint` and the spokes with `ip ospf network non-broadcast`.

Answer

Configure neighbor statements on all routers for every other router.

Answer

Change the OSPF network type to broadcast on all routers.

Question 4

A network engineer is troubleshooting a Cisco IOS XE router that runs MPLS L3VPN. The router is a PE and must exchange VPNv4 routes with a route reflector (RR). The engineer notices that VPNv4 prefixes are not being advertised to the RR. Which two configuration elements are required to enable VPNv4 route exchange? (Choose two.)

Accepted Answer

Activate the VPNv4 address family under the BGP routing process with `address-family vpnv4`.. To exchange VPNv4 routes, the PE router must have the VPNv4 address family activated under BGP and a route distinguisher configured under the VRF. The VPNv4 address family enables the BGP session to carry VPNv4 NLRI, while the RD ensures each VRF's prefixes are unique. Without both, the PE cannot generate or advertise VPNv4 routes to the route reflector, even if the underlying MPLS and BGP session are operational.

Answer

Activate the IPv4 address family under the VRF and redistribute connected routes.

Answer

Configure a route target (RT) export under the VRF definition with `route-target export`.

Answer

Enable MPLS LDP on the PE-to-RR interface with `mpls ip`.

Question 5

A network engineer is configuring EIGRP named mode on a Cisco IOS XE router. The engineer wants to ensure that the router advertises a default route into the EIGRP domain only when a specific prefix (10.1.1.0/24) is present in the routing table. Which configuration accomplishes this?

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

Accepted Answer

Configure a distribute-list with an ACL that denies 10.10.10.0/24 and permits any, applied outbound on GigabitEthernet0/0 under the EIGRP process.. To prevent a specific prefix from being advertised out an interface in EIGRP, use a distribute-list with an ACL that denies the prefix and permits all others, applied outbound on that interface under the EIGRP process. This filters the routing updates sent out the interface, ensuring the prefix is not advertised while other prefixes are. Other options either do not filter (offset-list) or use unsupported syntax (prefix-list directly, or route-map without proper application).

Answer

Configure an offset-list with an ACL that denies 10.10.10.0/24 and permits any, applied outbound on GigabitEthernet0/0 under the EIGRP process.

Answer

Configure a prefix-list that denies 10.10.10.0/24 and permits any, and apply it as an outbound distribute-list on GigabitEthernet0/0 under the EIGRP process.

Answer

Configure a route-map that denies 10.10.10.0/24 and permits any, and apply it as an outbound distribute-list on GigabitEthernet0/0 under the EIGRP process.

Question 6

A network engineer is configuring a Cisco IOS XE router for MPLS Layer 3 VPN. The engineer has enabled MPLS IP on the core interfaces and configured VRFs. The engineer now needs to enable MP-BGP to exchange VPNv4 prefixes with a remote PE router. Which two statements about the required MP-BGP configuration are true? (Choose two.)

Accepted Answer

The neighbor must be configured with the `send-community extended` command under the VPNv4 address family.. To exchange VPNv4 prefixes in MPLS L3VPN, the BGP neighbor must be activated under the VPNv4 address family, and extended communities must be sent because they carry the route target and route distinguisher. Without activation under VPNv4, no VPNv4 routes are exchanged. Without extended communities, the receiving PE cannot properly import routes into VRFs. Other commands like route-reflector-client or next-hop-self are conditional based on network design and not mandatory for basic MP-BGP VPNv4 operation.

Answer

The neighbor must be configured with the `next-hop-self` command under the VPNv4 address family.

Answer

The neighbor must be activated under the IPv4 unicast address family to exchange VPNv4 prefixes.

Answer

The neighbor must be configured with the `route-reflector-client` command under the VPNv4 address family if the neighbor is an iBGP peer.

Question 7

A network engineer is configuring a Cisco IOS XE router to authenticate OSPFv2 neighbors using MD5. The router is running OSPF process 1 and is connected to a broadcast network. The engineer wants to enable MD5 authentication on interface GigabitEthernet0/0 with key ID 1 and password 'Cisco123'. Which configuration is correct?

Accepted Answer

Under the OSPF process, configure `area 0 authentication message-digest`. On the interface, configure `ip ospf message-digest-key 1 md5 Cisco123`.. OSPFv2 MD5 authentication requires enabling MD5 authentication for the area (or interface) and configuring a message-digest key on the interface. The correct commands are `area 0 authentication message-digest` under the OSPF process and `ip ospf message-digest-key 1 md5 Cisco123` on the interface. The key ID and password must match on all neighbors. Simple password authentication uses different commands and is less secure.

Answer

On the interface, configure `ip ospf authentication message-digest` and `ip ospf message-digest-key 1 md5 Cisco123`.

Answer

Under the OSPF process, configure `area 0 authentication` and on the interface configure `ip ospf authentication-key Cisco123`.

Answer

On the interface, configure `ip ospf authentication-key 1 md5 Cisco123`.

Question 8

A network engineer is troubleshooting a DMVPN Phase 3 hub-and-spoke topology. Spoke routers are Cisco IOS devices running EIGRP as the routing protocol. The engineer wants to ensure that spoke-to-spoke traffic does not go through the hub after the initial path setup, and that spoke routers can dynamically form direct tunnels. Which NHRP command must be configured on the hub to enable this behavior?

Accepted Answer

ip nhrp redirect. For DMVPN Phase 3, the hub must be configured with 'ip nhrp redirect' to send redirect messages to spokes, allowing them to establish direct tunnels. Spokes must have 'ip nhrp shortcut' to act on those redirects. Without the hub redirect, spokes would continue sending traffic through the hub even after initial NHRP resolution.

Answer

ip nhrp map multicast dynamic

Answer

ip nhrp network-id 1

Answer

ip nhrp shortcut

Question 9

A network engineer is configuring a static route on a Cisco IOS router to reach the network 192.168.2.0/24 via the next-hop address 10.1.1.2. The engineer enters the command 'ip route 192.168.2.0 255.255.255.0 10.1.1.2'. However, the route does not appear in the routing table. What is the most likely reason?

Accepted Answer

The next-hop address 10.1.1.2 is not reachable.. A static route is only installed in the routing table if its next-hop address is reachable. The next-hop 10.1.1.2 must be reachable via a directly connected interface or another route. If it is not reachable, the static route remains in the configuration but is not active. The subnet mask is correct, and no special keywords are needed for basic installation. Thus, the most likely reason is that the next-hop is unreachable.

Answer

The static route requires the 'permanent' keyword to be installed.

Answer

The subnet mask is incorrect; it should be 255.255.255.0.

Answer

The router needs a default route to install any static route.

Question 10

A network engineer is configuring OSPFv3 on a Cisco router. The router has two interfaces in Area 0: GigabitEthernet0/0 (IPv6 address 2001:db8:1::1/64) and GigabitEthernet0/1 (IPv6 address 2001:db8:2::1/64). After enabling IPv6 unicast routing and configuring OSPFv3 with the router-id 1.1.1.1, the engineer notices that no OSPFv3 neighbors are forming. Which action is most likely to resolve the issue?

Accepted Answer

Enable OSPFv3 on the interfaces using the ipv6 ospf 1 area 0 command.. OSPFv3 requires enabling the protocol on each interface using the ipv6 ospf process-id area area-id command. Without this, the interface does not participate in OSPFv3, and no hellos are sent or received. The router ID and network type are secondary. Assigning IPv6 addresses from the same subnet is irrelevant because OSPFv3 uses link-local addresses for neighbor discovery.

Answer

Assign IPv6 addresses from the same subnet to both interfaces.

Answer

Set the OSPFv3 network type to point-to-point on both interfaces.

Answer

Configure a 64-bit router ID using the router-id command under the OSPFv3 process.

Question 11

A network engineer is configuring policy-based routing (PBR) on a Cisco IOS router. The engineer wants to route traffic from subnet 10.1.1.0/24 to a specific next-hop 192.168.1.1, while all other traffic uses the default route. The engineer configures a route map named PBR with a match statement for the subnet and a set statement for the next-hop, and applies it to the inbound interface of the subnet. However, traffic from 10.1.1.0/24 is still following the default route. What is the most likely reason?

Accepted Answer

The 'ip policy route-map' command is missing on the interface.. Policy-based routing requires the route map to be applied to an interface using the 'ip policy route-map' command. Without this command, the route map is not evaluated, and traffic follows the standard routing table. The engineer created the route map but likely did not apply it to the interface. Applying it to the inbound interface is correct for matching traffic from the subnet. The next-hop reachability is important but not the primary cause if PBR is not enabled.

Answer

The next-hop 192.168.1.1 is not reachable, so PBR is ignored.

Answer

The route map must be applied to the outbound interface instead of the inbound interface.

Answer

The route map is missing a 'permit' statement, causing all traffic to be denied.

Question 12

A network engineer is configuring MPLS Layer 3 VPN on a Cisco IOS XR router. The engineer needs to ensure that customer routes are properly propagated across the MPLS core. Which two of the following are required to establish the VPNv4 peering between PE routers? (Choose two.)

Accepted Answer

Enable BGP address-family vpnv4 unicast on the PE routers.. To establish VPNv4 peering between PE routers, you must enable the BGP VPNv4 address family and have either a full mesh of iBGP sessions or a route reflector. These two elements allow the exchange of VPNv4 routes with route distinguishers and route targets, which are essential for MPLS L3VPN. LDP and IGP are for transport but not for VPNv4 peering itself.

Answer

Configure OSPF as the IGP for the MPLS core.

Answer

Enable LDP for label distribution on the core interfaces.

Answer

Enable BGP address-family ipv4 unicast for customer routes.

Question 13

A network engineer is configuring EIGRP named mode on a Cisco IOS XE router. The engineer wants to ensure that the router advertises a default route into the EIGRP domain only when a specific prefix (10.1.1.0/24) is present in the routing table. Which configuration accomplishes this?

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

Accepted Answer

network 10.1.1.0 0.0.0.255 and network 10.2.2.0 0.0.0.255. To enable EIGRP for IPv4 on interfaces, you use the network command under router eigrp with a wildcard mask. Each network statement specifies a range of addresses; the wildcard mask 0.0.0.255 matches a /24 subnet. Two statements are needed to cover both 10.1.1.0/24 and 10.2.2.0/24. The other options are either too broad, invalid syntax, or for IPv6.

Answer

network 10.0.0.0

Answer

ipv6 eigrp 100 on each interface

Answer

network 10.0.0.0 0.255.255.255

Question 14

A network administrator is troubleshooting an OSPFv3 network. Routers R1 and R2 are in the same area and on the same broadcast segment, but they are not forming an adjacency. The administrator verifies that the interfaces are up and IPv6 addresses are configured correctly. Which command should be used to check if OSPFv3 is enabled on the interfaces?

Accepted Answer

show ipv6 ospf interface. To verify OSPFv3 interface configuration, the 'show ipv6 ospf interface' command is used. It shows whether OSPFv3 is enabled on the interface, the area, network type, and other parameters. This is the most direct way to confirm OSPFv3 is active on the interfaces.

Answer

show ipv6 protocols

Answer

show ipv6 ospf neighbor

Answer

show ipv6 ospf database

Question 15

A network engineer is configuring a route map for BGP policy. The engineer wants to match routes that originate from AS 65001 and have a community value of 100:200. The route map should then set the local preference to 200. Which configuration snippet accomplishes this?

Accepted Answer

ip as-path access-list 1 permit ^65001$
ip community-list standard 1 permit 100:200
route-map POLICY permit 10
 match as-path 1
 match community 1
 set local-preference 200. To match routes from AS 65001 with community 100:200 and set local preference, the configuration must include both an AS-path access list and a community list, and apply both matches in the route map. The correct snippet defines the AS-path access list with the regex ^65001$ to match routes originated in AS 65001, defines a standard community list to match 100:200, and then uses both in the route map with the set clause.

Answer

ip as-path access-list 1 permit ^65001$
route-map POLICY permit 10
 match as-path 1
 set local-preference 200

Answer

route-map POLICY permit 10
 match as-path 1
 match community 1
 set local-preference 200

Answer

ip community-list standard 1 permit 100:200
route-map POLICY permit 10
 match community 1
 set local-preference 200