300-410 Practice Test 21 — 15 Questions

Question 1

A network uses PBR to route traffic from a specific subnet (172.16.1.0/24) through a WAN link (next-hop 10.10.10.2). After a routing change, traffic from this subnet is being sent to the WAN link but is not reaching the destination. Router R1 shows: 'show route-map' shows the route-map is applied, 'debug ip policy' shows traffic being forwarded to 10.10.10.2, but 'show ip route' on R1 shows a route to the destination via a different next-hop (10.20.20.2). What is the root cause?

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

Accepted Answer

The next-hop 10.10.10.2 does not have a route to the destination, causing traffic to be dropped. Ensure the next-hop has a route to the destination or use a next-hop that does.. PBR forwards traffic to the set next-hop (10.10.10.2), but the routing table on R1 shows a different route to the destination. This indicates that PBR is overriding the routing table, but the next-hop 10.10.10.2 may not have a route to the destination, causing the traffic to be dropped. The solution is to ensure the next-hop has a route to the destination or use a different next-hop.

Answer

The route-map on R1 is missing a 'set ip next-hop verify-availability' command, causing PBR to use an unreachable next-hop.

Answer

The routing table on R1 has a better route to the destination via 10.20.20.2, but PBR is overriding it incorrectly.

Answer

The ACL in the route-map is matching traffic from the wrong subnet, causing PBR to be applied to the wrong traffic.

Question 2

What is the default action for a packet that does not match any route-map entry in a PBR policy?

Accepted Answer

The packet is forwarded using the routing table.. If no route-map entry matches, the packet is forwarded using the normal routing table lookup. PBR does not drop unmatched packets by default.

Answer

The packet is dropped.

Answer

The packet is sent to the CPU for processing.

Answer

The router sends an ICMP unreachable message.

Question 3

A large enterprise network is experiencing intermittent IPv6 connectivity loss for hosts on VLAN 100. Router R1 has the following relevant configuration:
interface GigabitEthernet0/0.100
 encapsulation dot1Q 100
 ipv6 address 2001:DB8:1:100::1/64
 ipv6 nd raguard
 ipv6 nd prefix default
 ipv6 dhcp relay destination 2001:DB8:1:200::1
!
Router R2 shows: debug ipv6 dhcp relay output indicates that DHCPv6 requests from VLAN 100 are being relayed, but the server never receives the SOLICIT messages. What is the root cause?

Accepted Answer

An IPv6 ACL applied to GigabitEthernet0/0.100 has an implicit deny that blocks the relayed DHCPv6 traffic.. An IPv6 ACL applied to the interface can implicitly deny the relayed DHCPv6 traffic. The debug output shows that DHCPv6 requests are being relayed from R1, but the server never receives the SOLICIT messages, indicating that the relayed packets are being dropped before leaving the router. An implicit deny in an IPv6 ACL on the outgoing interface (or inbound on the next hop) would block the relayed DHCPv6 unicast traffic, while the local relay process still sees the original client messages.

Answer

The 'ipv6 nd raguard' command on the interface filters DHCPv6 SOLICIT messages, preventing relay.

Answer

The DHCPv6 relay destination is in a different VRF, and the relay is not configured to use that VRF.

Answer

The DHCPv6 server is not configured to accept relayed messages from this relay agent.

Question 4

A network engineer is troubleshooting IPv6 redistribution between EIGRP and OSPFv3 on Router R1. Routes from OSPFv3 are being redistributed into EIGRP, but they are not appearing in the EIGRP topology table. Router R1 has the following relevant configuration:
router eigrp Test
 address-family ipv6 unicast
 redistribute ospf 1 metric 10000 100 255 1 1500
!
Router R2 shows: show ipv6 eigrp topology output does not include any OSPF-derived routes. What is the root cause?

Accepted Answer

The OSPFv3 process ID in the redistribute command does not match the actual OSPFv3 process ID running on the router.. The redistribute ospf 1 command references OSPFv3 process ID 1, but if the actual OSPFv3 process ID running on Router R1 is different (e.g., 100), the redistribution will silently fail—no routes are injected into EIGRP. The process ID must match exactly for redistribution to occur.

Answer

The EIGRP metric values are too high, causing the routes to be considered unreachable.

Answer

The routes from OSPFv3 are external, and EIGRP does not redistribute external OSPF routes by default.

Answer

The EIGRP address-family is not configured with a router ID, preventing redistribution.

Question 5

An engineer configured IP SLA 80 to monitor a remote server (192.168.100.100) using ICMP echo. The IP SLA is used in a track object for a static route. The engineer notices that the IP SLA state is 'Active', but the track object shows 'Down'. What is the most likely cause?

Accepted Answer

The track object is configured with a 'delay up' timer that has not yet expired.. The track object can be configured with a threshold (e.g., 'threshold' or 'delay') that causes it to remain 'Down' even if the IP SLA is 'Active'. For example, if the track object has a 'delay up' timer, it will not transition to 'Up' immediately.

Answer

The IP SLA probe is using a different source IP than expected.

Answer

The track object is referencing the wrong IP SLA number.

Answer

The router's routing table is full, preventing the track object from updating.

Question 6

Which of the following is a valid 'set' action in a PBR route-map?

Accepted Answer

set ip next-hop 10.0.0.1. PBR supports 'set ip next-hop', 'set interface', 'set ip default next-hop', 'set default interface', and 'set ip tos/precedence'. 'set metric' is not a PBR action.

Answer

set metric 100

Answer

set tag 5

Answer

set community 100:100

Question 7

Which statement about PBR and the 'set ip precedence' command is correct?

Accepted Answer

It modifies the IP header of the packet.. The 'set ip precedence' command sets the IP precedence bits in the Type of Service (ToS) field of the IP header, which can be used for QoS classification.

Answer

It sets the DSCP value.

Answer

It can only be used with 'set ip next-hop'.

Answer

It is used for load-balancing.

Question 8

In VRF-Lite, which routing protocols can be used within a VRF?

Accepted Answer

OSPF, EIGRP, RIP, and BGP can all be configured per VRF.. Most routing protocols (RIP, EIGRP, OSPF, BGP) support VRF-aware configurations. The protocol must be configured with the 'vrf' keyword to operate within a specific VRF.

Answer

Only static routing is supported in VRF-Lite.

Answer

Only OSPF and EIGRP are supported in VRF-Lite.

Answer

BGP cannot be used within a VRF in VRF-Lite.

Question 9

Which THREE commands can be used to verify VRF-Lite configuration and operation on a Cisco IOS-XE router? (Choose THREE.)

Accepted Answer

show vrf. Common verification commands for VRF-Lite include: 'show vrf' to list VRFs and their RD/RT, 'show ip route vrf ' to display the VRF-specific routing table, and 'show ip interface vrf ' to show interfaces assigned to a VRF. Option A is correct. Option B is correct. Option C is correct. Option D is incorrect because 'show ip vrf interfaces' is the correct command, not 'show vrf interfaces'. Option E is incorrect because 'show vrf detail' is not a valid command; the correct command is 'show vrf' or 'show vrf '.

Answer

show vrf interfaces

Answer

show vrf detail

Question 10

Consider the following configuration:
```
ip vrf CUSTOMER_E
 rd 200:1
 route-target export 200:1
 route-target import 200:1
!
interface GigabitEthernet0/0
 ip vrf forwarding CUSTOMER_E
 ip address 172.16.0.1 255.255.255.0
!
interface GigabitEthernet0/1
 ip vrf forwarding CUSTOMER_E
 ip address 172.16.1.1 255.255.255.0
```
What is the effect of the route-target commands in this VRF-Lite scenario?

Accepted Answer

The route-targets are ignored because VRF-Lite does not use MP-BGP.. In VRF-Lite, route-targets are not used unless route leaking is configured. They are typically used in MPLS VPN environments. Here, they have no effect because there is no MP-BGP or route leaking configured.

Answer

The route-targets enable automatic route redistribution between VRFs.

Answer

The route-targets cause the VRF to import and export routes from the global routing table.

Answer

The configuration will fail because route-targets are not allowed in VRF-Lite.

Question 11

What is the default administrative distance for a route installed by Policy-Based Routing (PBR) using the 'set ip next-hop' command?

Accepted Answer

The administrative distance of the routing protocol that learned the route.. PBR does not change the administrative distance of the route; the route is installed with the AD of the routing protocol that learned it. The 'set ip next-hop' command does not modify AD.

Answer

0

Answer

1

Answer

120

Question 12

A network engineer is troubleshooting a VRF-Lite setup where two routers are connected via a serial link. Each router has VRF_SALES configured. The engineer configures EIGRP in VRF_SALES. The 'show ip eigrp vrf VRF_SALES neighbors' shows no neighbors. The 'show ip eigrp vrf VRF_SALES interfaces' shows the serial interface is passive. What is the most likely cause?

Accepted Answer

The 'passive-interface default' command is configured under the EIGRP process for VRF_SALES.. If an interface is marked as passive in EIGRP, it will not send or receive hello packets, preventing neighbor formation. This is a common misconfiguration.

Answer

The 'network' command for the serial interface's subnet is missing.

Answer

The 'autonomous-system' number is different on the two routers.

Answer

The 'metric weights' command is misconfigured.

Question 13

Which statement correctly describes the behavior of PBR when the next-hop specified in a 'set ip next-hop' command is unreachable?

Accepted Answer

The router uses the routing table to forward the packet.. If the next-hop is unreachable, PBR will fall back to the normal routing table lookup, unless a 'set ip default next-hop' is configured.

Answer

The packet is dropped immediately.

Answer

The router sends an ICMP unreachable message.

Answer

The router uses the default route if configured.

Question 14

A network engineer is troubleshooting a VRF-Lite setup where a router is configured with VRF_GREEN. The engineer pings the gateway IP of a host in VRF_GREEN from the router, but the ping fails. The 'show ip route vrf VRF_GREEN' command shows the connected network for the host's subnet. The 'show ip interface brief' shows the interface is up/up. What is the most likely cause?

Accepted Answer

The host's IP address is not in the same subnet as the router's interface IP in VRF_GREEN.. If the interface is up and the route is present, the issue might be with ARP resolution or the host's configuration. However, in VRF-Lite, the router might not be able to ping the gateway if the gateway IP is not in the same subnet as the interface IP, or if the host has a firewall blocking ICMP.

Answer

The host's default gateway is not set to the router's interface IP in VRF_GREEN.

Answer

The router's interface in VRF_GREEN has 'ip proxy-arp' disabled.

Answer

The 'ip routing' command is disabled in VRF_GREEN.

Question 15

What is the default administrative distance for OSPF routes in a VRF-Lite environment on Cisco IOS-XE?

Accepted Answer

110. OSPF has a default administrative distance of 110 for all routes (intra-area, inter-area, and external).

Answer

90

Answer

120

Answer

170