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

Question 1

A network engineer is implementing route redistribution between OSPF and EIGRP on a Cisco IOS router. The engineer wants to prevent routing loops and ensure that routes redistributed from OSPF into EIGRP are not redistributed back into OSPF. Which mechanism should be used?

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

Accepted Answer

Configure a route map with a tag on OSPF routes and deny tagged routes when redistributing EIGRP into OSPF.. Route tagging is the most effective way to prevent routing loops during mutual redistribution. By assigning a tag to routes when they are redistributed from one protocol into another, you can later match and deny those tagged routes when redistributing back. This ensures that routes do not oscillate between protocols, maintaining a loop-free topology.

Answer

Set the administrative distance of EIGRP to a lower value than OSPF.

Answer

Use the default-metric command under the EIGRP process.

Answer

Apply a distribute-list to filter OSPF routes from being installed in the routing table.

Question 2

A network engineer is implementing CoPP on a Cisco router to protect the control plane from DoS attacks. The engineer wants to rate-limit ICMP echo requests destined to the router's management IP address. Which CoPP policy component is responsible for defining the traffic classification?

Accepted Answer

Class map. The correct answer is the class map, which defines the traffic classification by matching specific packet characteristics. In CoPP, class maps are used to identify traffic of interest, such as ICMP echo requests. The policy map then applies actions like policing to those classes. The service policy attaches the policy map to the control plane, and ACLs can be used within class maps for matching but are not the classification component themselves.

Answer

Access control list (ACL)

Answer

Policy map

Answer

Service policy

Question 3

A network technician is configuring a Cisco IOS router to authenticate EIGRP neighbors using MD5. The router is running EIGRP AS 10. Which command enables MD5 authentication for EIGRP on an interface?

Accepted Answer

ip authentication mode eigrp 10 md5. To enable MD5 authentication for EIGRP on an interface, you must use the ip authentication mode eigrp AS-number md5 command in interface configuration mode. This sets the authentication mode to MD5. You must also configure a key chain with keys and apply it using ip authentication key-chain eigrp AS-number key-chain-name. Both sides of the link must have matching key configurations.

Answer

authentication mode eigrp 10 md5

Answer

ip eigrp authentication md5

Answer

ip authentication key-chain eigrp 10 md5

Question 4

A network engineer is implementing policy-based routing (PBR) on a Cisco IOS XE router. The router has two interfaces: GigabitEthernet0/0 (LAN) and GigabitEthernet0/1 (WAN). A route-map named PBR-MAP is applied to GigabitEthernet0/0 with the command `ip policy route-map PBR-MAP`. The route-map contains a match statement for access-list 101, which permits traffic from 10.1.1.0/24 to any destination. The set statement is `set ip next-hop 192.168.2.1`. However, traffic from 10.1.1.0/24 is still being routed according to the routing table instead of being forwarded to 192.168.2.1. Which action should the engineer take to ensure PBR is applied?

Accepted Answer

Verify that the access-list 101 is correctly configured and matches the traffic, and that the route-map is applied to the correct interface in the inbound direction.. Policy-based routing requires the route-map to be applied to the inbound interface where traffic enters the router. The match conditions, such as an ACL, must correctly identify the traffic to be policy-routed. If the ACL is incorrect or the policy is not applied inbound, PBR will not override the routing table. Verifying these elements ensures that the policy is triggered and the set action is applied.

Answer

Enable PBR globally with the command `ip policy route-map PBR-MAP` in global configuration mode.

Answer

Configure a default route pointing to 192.168.2.1 to force all traffic through that next-hop.

Answer

Apply the route-map to the outbound direction on GigabitEthernet0/1 instead of inbound on GigabitEthernet0/0.

Question 5

A network engineer is configuring a Cisco IOS-XE router for DMVPN Phase 3. The engineer wants to ensure that spoke-to-spoke traffic flows directly between spokes without traversing the hub. Which technology should be used to achieve this?

Accepted Answer

NHRP redirect and NHRP shortcut. DMVPN Phase 3 uses NHRP redirect on the hub and NHRP shortcut on the spokes to enable direct spoke-to-spoke tunnels. Redirect informs spokes of a better path, and shortcut allows them to establish direct tunnels. Both are required to achieve the desired traffic flow without traversing the hub.

Answer

NHRP shortcut only

Answer

NHRP redirect only

Answer

Multicast NHRP mapping

Question 6

A network engineer is deploying DMVPN Phase 3 with EIGRP as the routing protocol over a hub-and-spoke topology. The hub router is configured with `ip nhrp redirect` on its tunnel interface, and each spoke has `ip nhrp shortcut`. A spoke needs to send traffic to a remote subnet behind another spoke. Which mechanism allows the spoke to install a direct route to the remote spoke's tunnel IP without traversing the hub for every packet?

Accepted Answer

NHRP resolution request triggered by the hub's redirect message, followed by installation of a shortcut entry in the NHRP cache and a /32 route in the RIB.. In DMVPN Phase 3, the hub uses NHRP redirect to tell a spoke that a better path exists. The spoke then sends an NHRP resolution request for the destination, receives the remote spoke's NBMA address, installs a shortcut entry, and creates a /32 route. This enables direct spoke-to-spoke forwarding without hairpinning through the hub for every packet.

Answer

The hub advertises a host route for each spoke's tunnel IP, and the spoke uses that route with the hub as next hop until the NHRP cache is populated by regular traffic.

Answer

The hub sends an ICMP redirect to the spoke, which then uses the hub's next-hop IP as the gateway for the remote subnet.

Answer

The spoke performs a recursive lookup on the hub's public IP and automatically derives the remote spoke's tunnel IP from the hub's NHRP database.

Question 7

A network engineer is troubleshooting a Cisco IOS XE router running OSPFv2. The router is an ABR between Area 0 and Area 1. Area 1 is configured as a Not-So-Stubby Area (NSSA). The engineer notices that a Type-7 LSA originated by an ASBR in Area 1 is not being translated into a Type-5 LSA by the ABR. Which condition would prevent the ABR from performing Type-7 to Type-5 translation?

Accepted Answer

The Type-7 LSA has the P-bit (Propagate bit) cleared, indicating that the LSA should not be translated by the ABR.. Type-7 to Type-5 translation in an NSSA depends on the P-bit in the Type-7 LSA. If the P-bit is cleared, the ABR will not translate the LSA into a Type-5 LSA, preventing the external route from being propagated into the backbone area. This bit is set by the originating ASBR and can be cleared in specific scenarios.

Answer

The ABR has a static route to the NSSA ASBR's loopback interface but no OSPF adjacency with the ASBR.

Answer

The ABR is not configured with the `area 1 nssa translate type7 always` command and there is another ABR with a higher router ID in the NSSA.

Answer

The forwarding address in the Type-7 LSA is set to 0.0.0.0 and the ABR has no route to the ASBR's router ID.

Question 8

A network engineer is configuring Policy-Based Routing (PBR) on a Cisco IOS-XE router. The engineer wants to route traffic from the 10.1.1.0/24 subnet that is destined for any TCP port 80 to next-hop 192.168.2.1, but only for packets arriving on GigabitEthernet0/1. Other traffic should follow the normal routing table. Which configuration sequence correctly accomplishes this?

Accepted Answer

Create an extended ACL that permits tcp 10.1.1.0 0.0.0.255 any eq 80, reference it in a route-map match statement, set the next-hop to 192.168.2.1, and apply the route-map to interface GigabitEthernet0/1 with the ip policy route-map command.. The correct configuration uses an extended ACL to match both source subnet and destination TCP port 80, references it in a route-map, sets the next-hop, and applies the route-map inbound on the specified interface. This ensures only HTTP traffic from 10.1.1.0/24 arriving on GigabitEthernet0/1 is policy-routed, while other traffic follows normal routing.

Answer

Create a route-map with a match statement for IP address 10.1.1.0/24 and a set statement for interface GigabitEthernet0/2, then apply it globally with the ip local policy route-map command.

Answer

Create a standard ACL that permits 10.1.1.0 0.0.0.255, reference it in a route-map match statement, set the next-hop to 192.168.2.1, and apply the route-map to interface GigabitEthernet0/1 with the ip policy route-map command.

Answer

Create a route-map with a match statement for IP address 10.1.1.0/24 and a set statement for next-hop 192.168.2.1, then apply it to interface GigabitEthernet0/1 using the ip policy route-map command.

Question 9

A network engineer is configuring a Cisco IOS router to run OSPFv3 for IPv6. The router must form an adjacency with a neighbor on a broadcast network. Which command is required to enable OSPFv3 on an interface?

Accepted Answer

ipv6 ospf 1 area 0. To enable OSPFv3 on an interface for IPv6, the command `ipv6 ospf 1 area 0` is used in interface configuration mode. This activates OSPFv3 on the interface and associates it with the specified area. The global command `ipv6 router ospf 1` is also needed to configure the router ID and other parameters, but the interface-level command is essential for adjacency formation.

Answer

ospfv3 1 ipv6 area 0

Answer

ipv6 ospf area 0

Answer

ipv6 router ospf 1

Question 10

A network engineer is troubleshooting a DMVPN Phase 3 network using EIGRP as the routing protocol. Spoke routers are unable to establish direct spoke-to-spoke tunnels. The engineer verifies that NHRP registration is successful and that the hub has routes to all spokes. Which action is most likely to resolve the issue?

Accepted Answer

Verify that the hub is configured with ip nhrp redirect and the spokes with ip nhrp shortcut.. In DMVPN Phase 3, spoke-to-spoke tunnels require ip nhrp redirect on the hub and ip nhrp shortcut on the spokes. These commands allow the hub to redirect traffic and the spokes to create shortcut routes. Without them, spokes will continue to route through the hub, even if NHRP registration is successful.

Answer

Ensure that the tunnel interfaces on all routers are configured with the same tunnel key.

Answer

Change the EIGRP network type on the tunnel interfaces to point-to-multipoint.

Answer

Configure EIGRP stub routing on the spoke routers.

Question 11

A network engineer is configuring a Cisco IOS router as a DHCP relay agent. The router's interface GigabitEthernet0/0 is connected to a client subnet, and the DHCP server is located at 10.1.1.100. The engineer wants the router to forward DHCP requests from clients to the server and ensure that the server can assign addresses from the correct pool. Which command is required on the router?

Accepted Answer

`ip helper-address 10.1.1.100` on interface GigabitEthernet0/0. To configure a Cisco IOS router as a DHCP relay agent, the `ip helper-address` command must be applied on the interface facing the DHCP clients. This command forwards DHCP broadcast requests to the specified DHCP server, allowing the server to assign addresses from the correct pool based on the incoming interface's IP address. Without this command, DHCP requests would not reach the server, and clients would not obtain IP addresses.

Answer

`ip dhcp relay information option` globally

Answer

`ip forward-protocol udp 67` on interface GigabitEthernet0/0

Answer

`ip dhcp pool CLIENT` and `network 192.168.1.0 /24`

Question 12

A network engineer is deploying BGP on a Cisco IOS XE router. The router must advertise the network 10.10.0.0/16 to an external peer, but the engineer notices that the prefix is not being advertised even though the network command is configured. The routing table shows that 10.10.0.0/16 is present as two separate /24 routes via OSPF. What is the most likely cause?

Accepted Answer

The network command requires an exact match in the routing table.. BGP network statements require an exact match in the routing table to originate a prefix. The routing table contains only the more specific /24 routes, so the /16 is not advertised. To resolve this, the engineer must create a matching route, such as a static route to Null0, or use the aggregate-address command with the summary-only option. The other options do not address the fundamental requirement of an exact match.

Answer

The BGP router ID is not reachable, preventing advertisement.

Answer

The BGP neighbor is configured with a send-community attribute that filters the prefix.

Answer

The OSPF routes are not being redistributed into BGP.

Question 13

A network engineer is configuring MPLS Layer 3 VPN on a Cisco IOS XE router. The engineer wants to enable the router to distribute VPNv4 prefixes to its PE peers. Which command must be configured under the BGP routing process to enable the address family?

Accepted Answer

address-family vpnv4. To enable the distribution of VPNv4 prefixes in MPLS L3VPN, the engineer must configure the address-family vpnv4 command under the BGP routing process. This enters the VPNv4 address family configuration mode, where neighbors can be activated and other parameters set. The other address families do not handle VPNv4 prefixes: ipv4 vrf is for VRF-specific routing, ipv4 unicast is for global IPv4, and vpnv6 is for IPv6 VPNs.

Answer

address-family ipv4 vrf

Answer

address-family ipv4 unicast

Answer

address-family vpnv6

Question 14

A network engineer is troubleshooting a DMVPN Phase 3 network using Cisco IOS XE routers. The hub router is configured with a multipoint GRE tunnel and NHRP. Spoke routers are unable to establish direct spoke-to-spoke tunnels. Which two statements describe the correct operation of DMVPN Phase 3 that could explain the issue? (Choose two.)

Accepted Answer

The hub must be configured with the ip nhrp redirect command to support Phase 3.. In DMVPN Phase 3, the hub must be configured with ip nhrp redirect, and spokes must be configured with ip nhrp shortcut. The redirect command allows the hub to notify spokes of a better path, while the shortcut command enables spokes to act on those notifications and establish direct tunnels. Without these, spoke-to-spoke traffic will continue to traverse the hub, even if other NHRP settings are correct.

Answer

Spokes must be configured with the ip nhrp network-id command matching the hub.

Answer

The hub must be configured with the ip nhrp map multicast dynamic command.

Answer

The hub must be configured with the ip nhrp authentication command.

Question 15

A network engineer is configuring a Cisco IOS XE router to support IPv6. The engineer wants to enable IPv6 routing and assign an IPv6 address to an interface. Which command must be configured globally to enable IPv6 routing?

Accepted Answer

ipv6 unicast-routing. To enable IPv6 routing globally on a Cisco IOS XE router, the engineer must configure the ipv6 unicast-routing command in global configuration mode. This command allows the router to forward IPv6 packets and participate in IPv6 routing protocols. The other options are either interface-level commands or invalid syntax. Without this command, the router will not route IPv6 traffic, even if interfaces are configured with IPv6 addresses.

Answer

ipv6 routing

Answer

ipv6 address autoconfig

Answer

ipv6 enable