300-410 Layer 3 Technologies Practice Test 16 — 15 Questions

Question 1

A network engineer is configuring a Cisco IOS XE router as a DHCP relay agent. The router is connected to a LAN segment with DHCP clients and must forward DHCP requests to a DHCP server at 10.1.1.100. Which command must be configured on the LAN interface to enable DHCP relay?

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

Accepted Answer

ip helper-address 10.1.1.100. To enable DHCP relay on a Cisco IOS XE router, the engineer must configure the ip helper-address command on the interface facing the DHCP clients, specifying the DHCP server's IP address. This command causes the router to forward DHCP broadcast requests as unicast packets to the server. The other options are either invalid commands or serve different purposes, such as configuring a DHCP server or modifying forwarded protocols.

Answer

ip dhcp pool 10.1.1.100

Answer

ip forward-protocol udp 67

Answer

ip dhcp relay 10.1.1.100

Question 2

A network engineer is troubleshooting a DMVPN Phase 3 network using Cisco IOS XE routers. Spoke routers are unable to establish direct spoke-to-spoke tunnels. The hub router is configured with 'ip nhrp redirect', and spokes are configured with 'ip nhrp shortcut'. The engineer notices that spoke routers are not receiving NHRP redirect messages from the hub. Which action should be taken to resolve this issue?

Accepted Answer

Ensure that the hub router has a route to the spoke networks and that NHRP resolution is working.. In DMVPN Phase 3, the hub uses 'ip nhrp redirect' to inform spokes of a better path to a destination. For the hub to send redirects, it must have a route to the destination network and be able to resolve the destination's NBMA address via NHRP. If the hub lacks a route or NHRP resolution fails, no redirects are sent, and spokes cannot establish direct tunnels. Verifying hub routing and NHRP operation is essential for troubleshooting this issue.

Answer

Configure 'ip nhrp map multicast dynamic' on the spoke routers.

Answer

Enable 'ip nhrp shortcut' on the hub router.

Answer

Change the tunnel mode from GRE multipoint to GRE point-to-point.

Question 3

A network engineer is troubleshooting a DMVPN Phase 3 network using Cisco IOS XE routers. The hub router (Hub1) has a public IP of 203.0.113.1 and is configured with `tunnel mode gre multipoint`. Spoke routers are behind NAT devices. Spoke1 cannot establish a direct spoke-to-spoke tunnel with Spoke2, although both can reach the hub. Which technology must be enabled on the hub to allow spoke-to-spoke direct tunnels in this scenario?

Accepted Answer

NHRP redirect. In DMVPN Phase 3, the hub uses NHRP redirect to notify spokes of a better path to another spoke. When Spoke1 sends traffic to Spoke2 via the hub, the hub sends an NHRP redirect, and Spoke1 then initiates a direct tunnel using NHRP shortcut. This is critical when spokes are behind NAT, as the hub facilitates the initial resolution and redirect.

Answer

NHRP shortcut

Answer

Multicast routing

Answer

IPsec tunnel protection

Question 4

A network engineer is troubleshooting a BGP routing issue on a Cisco IOS XE router. The router is configured with a route map that sets the local preference for routes learned from a specific neighbor. However, the engineer notices that the local preference is not being applied to routes received from that neighbor. Which BGP configuration command is most likely missing?

Accepted Answer

neighbor 10.1.1.1 route-map LOCAL-PREF in. To set local preference on routes learned from a specific BGP neighbor, a route map must be created that sets the local preference and then applied to that neighbor in the inbound direction. The correct command is neighbor route-map in. Without this, the route map is not applied, and local preference remains at the default value.

Answer

bgp default local-preference 200

Answer

neighbor 10.1.1.1 send-community

Answer

neighbor 10.1.1.1 soft-reconfiguration inbound

Question 5

A network engineer is troubleshooting an OSPFv3 network. Router R1 is an ABR connected to Area 0 and Area 1. Area 1 is configured as a totally stubby area. R1 is not injecting a default route into Area 1, and routers in Area 1 cannot reach external destinations. Which command should the engineer verify on R1 to ensure that a default route is generated into Area 1?

Accepted Answer

`area 1 stub no-summary` under the OSPFv3 process.. In OSPFv3, a totally stubby area is configured on the ABR with the `area <area-id> stub no-summary` command. This command blocks type 3 summary LSAs and causes the ABR to inject a default route (inter-area-prefix LSA) into the area. Without it, routers in the area have no default route and cannot reach external networks. The engineer should verify that this command is present on R1.

Answer

`summary-address` under the OSPFv3 process.

Answer

`default-information originate` under the OSPFv3 process.

Answer

`area 1 nssa no-summary` under the OSPFv3 process.

Question 6

A network engineer is implementing MPLS Layer 3 VPN on a Cisco IOS XE router. The engineer wants to ensure that customer routes are advertised with the correct route distinguisher (RD) and route target (RT) extended communities. Which BGP address family must be configured to exchange VPNv4 routes between PE routers?

Accepted Answer

address-family vpnv4 unicast. MPLS Layer 3 VPN uses BGP VPNv4 address family to exchange customer routes between PE routers. The VPNv4 address family carries the RD and RT extended communities that identify the VPN and control import/export. It must be activated on the PE-PE BGP session. The VRF address family is used for PE-CE routing and for assigning RDs and RTs, but not for exchanging VPNv4 routes.

Answer

address-family ipv4 vrf CUSTOMER

Answer

address-family ipv4 multicast

Answer

address-family ipv4 unicast

Question 7

A network engineer is configuring a Cisco IOS XE router as a DHCP relay agent. The router is connected to a LAN segment with DHCP clients and must forward DHCP requests to a DHCP server at 10.1.1.100. Which command must be configured on the LAN interface to enable DHCP relay?

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

Accepted Answer

`ip nhrp redirect` on the hub tunnel interface.. DMVPN Phase 3 enables spoke-to-spoke communication with hub assistance. The hub uses `ip nhrp redirect` to send redirect messages to spokes when it detects that traffic between spokes could take a direct path. Spokes then use `ip nhrp shortcut` to create a direct tunnel. The hub must have `ip nhrp redirect` configured; otherwise, spokes never receive the redirect and continue to send traffic through the hub.

Answer

`ip nhrp shortcut` on the hub tunnel interface.

Answer

`ip nhrp network-id 100` on the spoke tunnel interfaces.

Answer

`ip nhrp map multicast dynamic` on the spoke tunnel interfaces.

Question 8

A network engineer is configuring a Cisco IOS XE router for MPLS Layer 3 VPN. The router is a PE connected to a CE via GigabitEthernet0/0. The engineer wants to configure a VRF named CUSTOMER_A and assign the interface to it. The engineer enters the following commands: `vrf definition CUSTOMER_A`, `rd 65000:1`, `address-family ipv4`, `exit`, `exit`. Then, under interface GigabitEthernet0/0, the engineer enters `vrf forwarding CUSTOMER_A`. After entering the command, the engineer notices that the IP address on the interface is removed. What is the most likely reason?

Accepted Answer

The `vrf forwarding` command removes the IP address because the interface must be reconfigured with an IP address within the VRF.. Assigning an interface to a VRF with `vrf forwarding` removes the existing IP address. This is by design because the interface's IP address must be unique within the VRF. The engineer must reconfigure the IP address after the VRF assignment. The other options describe unrelated VRF configuration steps or incorrect requirements.

Answer

The VRF definition must include `address-family ipv4` before the interface can be assigned, and the missing address-family caused the IP removal.

Answer

The interface must be shut down before assigning it to a VRF, otherwise the IP address is cleared.

Answer

The VRF definition is missing the `route-target export` and `route-target import` commands.

Question 9

A network engineer is configuring Policy-Based Routing (PBR) on a Cisco IOS XE router. The engineer wants to forward traffic matching a specific ACL to a next-hop IP address, but only if the next-hop is reachable. Which command should be used in the route map to specify the next-hop and enable tracking?

Accepted Answer

set ip next-hop verify-availability 10.1.1.1 1 track 1. To conditionally forward traffic based on next-hop reachability in PBR, the set ip next-hop verify-availability command is used. It references a tracking object that monitors the next-hop. If the track is up, the next-hop is used; if down, the route map is skipped, and normal routing applies. This provides the required conditional forwarding.

Answer

set ip next-hop 10.1.1.1

Answer

set ip default next-hop 10.1.1.1

Answer

set ip next-hop recursive 10.1.1.1

Question 10

A network engineer is implementing MPLS Layer 3 VPN on a Cisco IOS-XE router. The engineer needs to configure the router to exchange VPNv4 routes with a route reflector. The router is already configured with BGP AS 65001 and has established an IBGP session with the route reflector. Which address family must be activated to support VPNv4 route exchange?

Accepted Answer

address-family vpnv4 unicast. MPLS L3VPN uses the VPNv4 address family to exchange labeled VPN routes between PE routers. The VPNv4 address family carries the route distinguisher and route target extended communities. Activating it under the BGP routing process on both the PE and route reflector is required. Without it, VPNv4 prefixes are not propagated.

Answer

address-family ipv6 unicast

Answer

address-family ipv4 vrf

Answer

address-family ipv4 unicast

Question 11

A network engineer is troubleshooting a DMVPN Phase 3 network using Cisco IOS-XE routers. The hub router is configured with `ip nhrp redirect` and spoke routers with `ip nhrp shortcut`. A spoke router is unable to establish a direct spoke-to-spoke tunnel for a specific destination. Which action should the engineer take to resolve this?

Accepted Answer

Ensure that the spoke routers have a route to the destination network via the hub.. DMVPN Phase 3 relies on NHRP redirects from the hub to trigger spoke-to-spoke shortcuts. For the spoke to send initial traffic to the hub and receive a redirect, it must have a route to the destination via the hub. This route is typically learned through the routing protocol running over the DMVPN. Without it, the spoke cannot initiate the shortcut process.

Answer

Disable `ip split-horizon` on the hub's tunnel interface.

Answer

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

Answer

Configure `ip nhrp nhs` on the spoke to point to the hub.

Question 12

A network engineer is troubleshooting a Cisco IOS XE router that is configured with a route map for policy-based routing (PBR). The route map is applied to the ingress interface with `ip policy route-map PBR`. The engineer wants to verify that the PBR is matching traffic and setting the next-hop correctly. Which command provides the most detailed information about PBR matches and actions?

Accepted Answer

debug ip policy. For detailed PBR troubleshooting, `debug ip policy` is the most informative command. It logs each packet's match against route map sequences and shows the set actions applied, such as next-hop or interface. While `show route-map` provides configuration and some counters, it lacks the per-packet detail. `show ip policy` only confirms attachment. Thus, the debug command is the correct choice for verifying matches and next-hop settings.

Answer

show route-map PBR

Answer

show ip policy

Answer

show ip route

Question 13

A network engineer is configuring policy-based routing (PBR) on a Cisco IOS XE router. The router has two interfaces: GigabitEthernet0/0 (10.1.1.1/24) and GigabitEthernet0/1 (10.2.2.1/24). The engineer wants traffic from the 10.1.1.0/24 subnet destined to 192.168.1.0/24 to be forwarded out GigabitEthernet0/1 instead of following the routing table, which points to GigabitEthernet0/0. Which configuration sequence correctly implements this requirement?

Accepted Answer

Create a route map that matches the source subnet and sets the next-hop to 10.2.2.2, then apply it to interface GigabitEthernet0/0 with the ip policy route-map command.. Policy-based routing allows the engineer to override the destination-based routing table by matching source addresses and setting a next-hop. The route map must be applied inbound on the interface where traffic enters the router. The set next-hop must point to a device reachable via the desired egress interface. This ensures only the specified source subnet is policy-routed, while other traffic follows normal routing.

Answer

Create an access list that permits the source subnet, apply it to interface GigabitEthernet0/1 with the ip access-group command, and set the default gateway to 10.2.2.2.

Answer

Configure a static route for 192.168.1.0/24 pointing to 10.2.2.2 with a lower administrative distance, and redistribute it into the routing protocol.

Answer

Enable PBR globally with the ip policy route-map command in global configuration mode, and reference a route map that sets the interface to GigabitEthernet0/1.

Question 14

A network engineer is configuring a Cisco IOS XE router as a DHCP relay agent. The router is connected to a LAN segment with DHCP clients and must forward DHCP requests to a DHCP server at 10.1.1.100. Which command must be configured on the LAN interface to enable DHCP relay?

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

Accepted Answer

AS path. AS path prepending is the technique of adding multiple instances of the local AS number to the AS path attribute in BGP updates sent to external peers. This makes the route less attractive because a longer AS path is less preferred. It is a standard method to influence inbound traffic from an ISP. Local preference and weight affect outbound traffic, while MED is an alternative but less forceful method for inbound influence.

Answer

Weight

Answer

Multi-exit discriminator (MED)

Answer

Local preference

Question 15

A network engineer is configuring EIGRP for IPv6 on a Cisco IOS XE router. The router has two interfaces: GigabitEthernet0/0 (2001:DB8:1::1/64) and GigabitEthernet0/1 (2001:DB8:2::1/64). The engineer wants to enable EIGRP for IPv6 on both interfaces and ensure that the router forms adjacencies. Which configuration is required?

Accepted Answer

Enable IPv6 unicast routing globally, create an EIGRP for IPv6 routing process, and enable EIGRP on each interface with the ipv6 eigrp command.. EIGRP for IPv6 requires IPv6 unicast routing to be enabled globally, creation of an EIGRP for IPv6 routing process, and explicit enabling of EIGRP on each interface using the ipv6 eigrp command. Unlike IPv4 EIGRP, there is no network command; interfaces must be enabled individually. This ensures the router can form adjacencies and exchange IPv6 routing information.

Answer

Enable IPv6 unicast routing globally, configure an EIGRP for IPv6 routing process, and use the network command under the routing process to advertise the interfaces.

Answer

Enable IPv6 unicast routing globally, configure EIGRP for IPv6 with the no shutdown command under the routing process, and assign IPv6 addresses to interfaces.

Answer

Enable IPv6 unicast routing globally, configure EIGRP for IPv6, and enable EIGRP on interfaces using the ipv6 router eigrp command under each interface.