300-410 Infrastructure Services Practice Test 8 — 15 Questions

Question 1

A network engineer is deploying MPLS L3VPN on a Cisco IOS XE PE router. The PE router must advertise VPNv4 routes to a remote PE router using MP-BGP. The engineer has configured the address-family ipv4 vrf CUSTOMER and redistributed the static routes into BGP. However, the remote PE router does not receive any VPNv4 prefixes. Which command is required on the PE router to enable the exchange of VPNv4 prefixes with the remote PE?

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

Accepted Answer

address-family vpnv4 unicast. For MPLS L3VPN, the PE routers must exchange VPNv4 prefixes using MP-BGP. This requires the VPNv4 address family to be enabled under BGP and the remote PE neighbor to be activated within that address family. Without it, the PE only exchanges IPv4 unicast routes and does not include the route distinguisher or route target extended communities, so the remote PE cannot import the routes into the correct VRF. The correct command activates the necessary address family.

Answer

mpls ldp router-id Loopback0 force

Answer

address-family ipv4 vrf CUSTOMER

Answer

neighbor <remote-pe-ip> send-community extended

Question 2

A network engineer is configuring a Cisco IOS XE router to support MPLS L3VPN with a VRF named CUST. The customer edge (CE) router uses eBGP, and the service provider requires that the CE's autonomous system number be preserved end-to-end. The PE router must accept routes with the CE's AS number in the AS_PATH. Which BGP feature must be configured on the PE router?

Accepted Answer

neighbor <CE-IP> allowas-in. The allowas-in feature allows a BGP speaker to accept routes that contain its own AS number in the AS_PATH, which is necessary when the CE's AS number must be preserved and may appear in updates. The as-override feature does the opposite by replacing the CE's AS number, and the other options do not influence AS_PATH loop detection.

Answer

neighbor <CE-IP> send-community

Answer

neighbor <CE-IP> route-reflector-client

Answer

neighbor <CE-IP> as-override

Question 3

A network engineer is configuring a Cisco IOS XE router to serve as a DHCP relay agent for a remote subnet. The DHCP server is at 10.1.1.10, and the router interface facing the clients is GigabitEthernet0/1 with IP address 10.2.2.1/24. The engineer wants the relay agent to insert the client's subnet information into DHCP requests. Which command is required on the interface?

Accepted Answer

ip helper-address 10.1.1.10. The ip helper-address command on the client-facing interface is the essential configuration for DHCP relay. It forwards client broadcasts to the specified server and populates the giaddr field with the interface IP, enabling the server to assign addresses from the correct subnet. Other commands either add optional features or mistakenly configure the router as a server.

Answer

ip forward-protocol udp 67

Answer

ip dhcp relay information option

Answer

ip dhcp pool REMOTE
 network 10.2.2.0 255.255.255.0

Question 4

A network engineer is configuring a Cisco IOS XE router as a PE device in an MPLS L3VPN environment. The router must support a VRF named BLUE for a customer that uses OSPF as the PE-CE routing protocol. The engineer has configured the VRF, assigned interfaces, and set up MP-BGP. However, the customer reports that routes from the BLUE VRF are not being advertised into MP-BGP. Which command must be configured under the BGP address-family configuration to redistribute the OSPF routes from the VRF into MP-BGP?

Accepted Answer

redistribute ospf 1. In an MPLS L3VPN PE router, customer routes learned via the PE-CE routing protocol (OSPF) must be redistributed into MP-BGP under the VRF address-family. The command 'redistribute ospf 1' within the 'address-family ipv4 vrf BLUE' context accomplishes this. It takes OSPF routes from the VRF and advertises them as VPNv4 routes to other PEs. This is essential for end-to-end customer connectivity.

Answer

import route-target BLUE

Answer

redistribute ospf 1 vrf BLUE

Answer

redistribute connected

Question 5

A network engineer is configuring a Cisco IOS XE router to act as a DHCP relay agent. The DHCP server is on a remote subnet, and the router's interface facing the clients is GigabitEthernet0/1 with IP address 10.1.1.1/24. The DHCP server's IP address is 10.2.2.2. The engineer wants to ensure that DHCP requests are forwarded correctly and that the server can assign addresses from the correct pool. Which two commands are required to configure the relay agent on the router? (Choose two.)

Accepted Answer

interface GigabitEthernet0/1; ip helper-address 10.2.2.2. To configure a Cisco router as a DHCP relay agent, you must configure the client-facing interface with an IP address and then apply the 'ip helper-address' command pointing to the DHCP server. The interface IP is necessary for the router to be reachable and to set the giaddr field, while 'ip helper-address' enables the relay function. These two commands are the minimum required for basic DHCP relay operation.

Answer

ip dhcp pool CLIENT_POOL; network 10.1.1.0 255.255.255.0; default-router 10.1.1.1

Answer

ip forward-protocol udp 67

Answer

ip dhcp relay information option

Question 6

A network engineer is deploying a Cisco IOS XE router as a Dynamic Multipoint VPN (DMVPN) hub in a Phase 2 topology. The design requires that all spoke-to-spoke traffic traverse the hub rather than building direct spoke-to-spoke tunnels. Which configuration on the hub tunnel interface ensures this behavior?

Accepted Answer

no ip next-hop-self eigrp 100. In a DMVPN Phase 2 topology, spoke-to-spoke traffic can either go through the hub or build direct tunnels. To force all traffic through the hub, the hub must not allow spokes to learn each other's real next-hop addresses. The command no ip next-hop-self eigrp 100, when removed (i.e., next-hop-self enabled), achieves this by making the hub the next hop for all routes. However, the question asks which configuration ensures hub traversal; the presence of next-hop-self on the hub is the key. Among the options, the command that explicitly prevents direct tunnels is the one that keeps next-hop-self enabled, which is represented by the absence of the no form. The correct answer is the one that maintains hub-and-spoke forwarding.

Answer

ip nhrp redirect

Answer

no ip split-horizon eigrp 100

Answer

ip next-hop-self eigrp 100

Question 7

A network engineer is configuring a Cisco IOS XE router to support MPLS L3VPN with a VRF named CUSTOMER. The engineer must ensure that the PE router can import and export routes correctly using route targets. Which two commands are required to configure route targets for the VRF? (Choose two.)

Accepted Answer

route-target export 65000:100. To configure route targets for a VRF in MPLS L3VPN, the engineer must set both the export and import route targets using separate commands under the VRF address family. The export route target is attached to routes leaving the VRF, and the import route target determines which routes are accepted. Both are required for proper route distribution.

Answer

route-target both 65000:100

Answer

route-target import 65000:100 and route-target export 65000:100

Answer

route-target export 65000:100 and route-target import 65000:100

Question 8

A network engineer is configuring a Cisco IOS XE router to act as a DHCP server for a subnet. The engineer wants the router to automatically update DNS records for DHCP clients. Which command must be configured globally to enable this feature?

Accepted Answer

ip dhcp update dns. The ip dhcp update dns command is the global configuration that enables the DHCP server to dynamically update DNS records for its clients. It must be used in conjunction with other parameters such as the DNS server address and domain name. Other commands either configure DNS for the router itself or define update methods that are not the primary enablement for DHCP-driven updates.

Answer

ddns update method

Answer

ip ddns update method

Answer

ip name-server

Question 9

A network engineer is configuring a Cisco IOS XE router to support MPLS Layer 3 VPNs. The router is a PE device and must exchange VPNv4 routes with a remote PE. The engineer has enabled MPLS IP on the core interfaces and configured a VRF named CUSTOMER. Which two additional configurations are required to establish the MP-BGP session and exchange VPNv4 routes? (Choose two.)

Accepted Answer

Enable address-family ipv4 vrf CUSTOMER under the BGP routing process.. To establish an MP-BGP session and exchange VPNv4 routes, the PE router must have a route distinguisher configured for the VRF to create unique VPNv4 prefixes. Additionally, the VRF address family must be activated under BGP so that routes from that VRF can be redistributed into MP-BGP and advertised as VPNv4 updates. Without these two, the PE cannot generate or advertise VPNv4 routes for the customer VRF. Route targets are needed for proper import/export but are not required for the session itself, and LDP is for label distribution, not BGP session establishment.

Answer

Configure a route target (RT) import and export policy under the VRF.

Answer

Enable MPLS LDP on the core-facing interfaces.

Answer

Activate the VPNv4 address family under the BGP routing process.

Question 10

A network engineer is configuring a Cisco IOS router to act as a DHCP server for a subnet. The router must assign IP addresses to clients on the 10.1.1.0/24 network. The engineer wants to ensure that the router does not assign the first 10 addresses and the last address of the subnet. Which command accomplishes this?

Accepted Answer

ip dhcp excluded-address 10.1.1.1 10.1.1.10 followed by a separate command ip dhcp excluded-address 10.1.1.254. The ip dhcp excluded-address command can specify a single address or a range. To exclude both a range and a separate single address, two separate commands are required. The correct approach is to enter one command for the range 10.1.1.1 to 10.1.1.10 and another for 10.1.1.254. Combining them in a single command or using non-standard syntax will not work. The correct answer is the one that reflects this two-command method.

Answer

ip dhcp excluded-address 10.1.1.1 10.1.1.10 10.1.1.254

Answer

ip dhcp excluded-address 10.1.1.1 10.1.1.10

Answer

ip dhcp excluded-address 10.1.1.1 10.1.1.10 and ip dhcp excluded-address 10.1.1.254

Question 11

A network engineer is troubleshooting an MPLS L3VPN where OSPF is used as the PE-CE routing protocol. The customer reports that routes from one site are not being advertised to another site. The engineer verifies that the OSPF neighbor relationship between the CE and PE is up and that routes are present in the OSPF database. Which configuration on the PE router is most likely missing to allow the routes to be redistributed into MP-BGP?

Accepted Answer

redistribute ospf 1 into bgp under the VRF address family. For OSPF routes from a customer VRF to be advertised across the MPLS L3VPN, the PE router must redistribute those OSPF routes into BGP within the VRF address family. This step exports the routes as VPNv4 updates to other PEs. Without it, the routes remain local to the PE and are not propagated. While domain-id and capability vrf-lite are important for loop prevention and correct behavior, they do not replace the need for redistribution. The correct answer is the redistribution command under the BGP VRF address family.

Answer

domain-id under the OSPF process

Answer

capability vrf-lite under the OSPF process

Answer

redistribute bgp into ospf under the OSPF process

Question 12

A network engineer is configuring a Cisco IOS router to provide first-hop redundancy for a group of hosts on VLAN 10. The design requires that the virtual IP address be 10.10.10.1 and that the router with the highest priority become the active gateway. The engineer also wants to ensure that if the active router fails, the standby router takes over within 3 seconds. Which protocol and configuration should be used?

Accepted Answer

HSRP with standby 10 ip 10.10.10.1 and standby 10 timers 1 3. HSRP is a Cisco-proprietary first-hop redundancy protocol that provides active/standby gateway redundancy. The virtual IP is configured with standby group ip, and timers are set with standby group timers hello hold. To achieve failover within 3 seconds, a hello time of 1 second and a hold time of 3 seconds is appropriate. The highest priority router becomes active. VRRP and GLBP could also provide redundancy, but HSRP is the most direct fit for the stated requirements. The invalid timer order in another option makes it incorrect.

Answer

VRRP with vrrp 10 ip 10.10.10.1 and vrrp 10 timers advertise 1

Answer

HSRP with standby 10 ip 10.10.10.1 and standby 10 timers 3 1

Answer

GLBP with glbp 10 ip 10.10.10.1 and glbp 10 timers 1 3

Question 13

A network engineer is deploying a DMVPN Phase 3 hub-and-spoke topology. The hub router must dynamically learn spoke-to-spoke routes and allow direct spoke-to-spoke tunnels. Which technology should be implemented on the hub to achieve this?

Accepted Answer

Enable NHRP redirect on the hub and NHRP shortcut on the spokes.. In DMVPN Phase 3, the hub uses NHRP redirect to inform spokes that a more optimal path exists directly to another spoke. Spokes then use NHRP shortcut to resolve the destination's NBMA address and establish a direct tunnel. This reduces hub transit and latency. The other options are valid DMVPN features but do not provide the dynamic spoke-to-spoke capability required.

Answer

Configure NHRP authentication and NHRP map entries on all routers.

Answer

Implement IPsec tunnel protection with IKEv2 and enable QoS pre-classify.

Answer

Use OSPF broadcast network type on all tunnel interfaces and enable split horizon.

Question 14

A network engineer is configuring a Cisco IOS XE router to support a DMVPN Phase 3 hub-and-spoke topology. The hub router must be able to redirect spoke-to-spoke traffic without requiring the spokes to have a direct route to each other. Which technology should be implemented on the hub to enable the hub to inform the originating spoke of the optimal spoke-to-spoke path?

Accepted Answer

NHRP redirect. In DMVPN Phase 3, the hub uses NHRP redirect to notify the originating spoke that a better path exists directly to the destination spoke. The spoke then sends an NHRP resolution request for the destination spoke's NBMA address and, upon receiving a reply, establishes a direct tunnel. This optimizes traffic flow and reduces hub load. NHRP shortcut on the spoke caches the direct path, but the hub's redirect is the trigger.

Answer

Multipoint GRE (mGRE)

Answer

IPsec tunnel protection

Answer

Next Hop Resolution Protocol (NHRP) shortcut

Question 15

A network administrator is troubleshooting an OSPFv3 network. Routers R1 and R2 are directly connected on a point-to-point link. R1 is configured with OSPFv3 area 0, and R2 is configured with OSPFv3 area 1. The administrator notices that no OSPFv3 adjacency forms between them. What is the most likely cause?

Accepted Answer

The OSPFv3 area numbers do not match on the link.. For OSPFv3 to form an adjacency, both routers on a common link must be configured in the same OSPF area. In this scenario, R1 is in area 0 and R2 is in area 1, which violates this requirement. The hello packets will be ignored, and no adjacency will form. Other potential issues like duplicate router IDs or interface configuration are not indicated by the symptoms.

Answer

The OSPFv3 router IDs are not unique.

Answer

The OSPFv3 process is not enabled on the interfaces.

Answer

The OSPFv3 network type is mismatched.