300-410 Practice Test 42 — 15 Questions

Question 1

An engineer configures BGP between two routers in the same AS. The iBGP session is established, but routes learned from the eBGP neighbor are not advertised to the iBGP peer. The 'show ip bgp' output shows the routes as valid but not best. Which is the most likely explanation?

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

Accepted Answer

The next-hop IP of the eBGP route is not reachable via IGP, making the route invalid.. For iBGP, the next-hop must be reachable via IGP. If the next-hop is not reachable (e.g., no IGP route for the eBGP peer's interface IP), the route is considered invalid and not installed. This is a common edge case where next-hop-self is not configured.

Answer

The 'synchronization' rule is enabled and the IGP does not carry the prefix.

Answer

The 'maximum-paths' command is set to 1, preventing load balancing.

Answer

The 'bgp bestpath med missing-as-worst' command causes the route to be considered worse.

Question 2

An engineer is redistributing OSPF routes into EIGRP. Which TWO commands can be used to verify that the redistribution is working correctly? (Choose TWO.)

Accepted Answer

show ip route eigrp. To verify redistribution, you can check the routing table of the receiving protocol (EIGRP) to see if the redistributed routes appear. Additionally, 'show ip eigrp topology' shows the EIGRP topology table, which includes redistributed routes. 'show ip ospf database' is for OSPF LSDB and does not show redistributed routes into EIGRP. 'show ip protocols' shows redistribution configuration but not active routes. 'show ip route eigrp' shows only EIGRP routes, but if redistribution is working, those routes should appear there.

Answer

show ip ospf database

Answer

show ip protocols

Answer

show ip route ospf

Question 3

A network engineer runs the following command to troubleshoot an EIGRP issue:

R1# show ip eigrp topology all-links

IP-EIGRP Topology Table for AS 100

Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
       r - Reply status, s - sia Status

P 10.1.1.0/24, 1 successors, FD is 131072
         via 10.1.2.2 (131072/130816), GigabitEthernet0/0
         via 10.1.3.3 (131328/131072), GigabitEthernet0/1
P 10.2.2.0/24, 1 successors, FD is 131072
         via 10.1.2.2 (131072/130816), GigabitEthernet0/0
A 10.3.3.0/24, 0 successors, FD is Infinity
         via 10.1.2.2 (4294967295/4294967295), GigabitEthernet0/0
         via 10.1.3.3 (4294967295/4294967295), GigabitEthernet0/1

What does this output indicate?

Accepted Answer

The route 10.3.3.0/24 is stuck-in-active because replies have not been received from all neighbors.. The 'A' code for route 10.3.3.0/24 indicates it is in the Active state, meaning the router has sent Queries for this route and is waiting for Replies from all neighbors. The FD (Feasible Distance) is 'Infinity' (4294967295), and both successors are 0, confirming the route is not usable. The 's' (sia Status) code is not shown, but the Active state with no successors and infinite metrics directly points to a stuck-in-active (SIA) condition where replies have not been received from all neighbors, causing the route to remain active.

Answer

The route 10.3.3.0/24 is passive and has two feasible successors.

Answer

The route 10.3.3.0/24 is learned via both neighbors with equal metrics.

Answer

The route 10.3.3.0/24 is installed in the routing table via both neighbors.

Question 4

Router R2 has the following configuration:
```
interface GigabitEthernet0/2
 ip address 10.2.2.2 255.255.255.0
 ip policy route-map CHECK
!
route-map CHECK permit 10
 match ip address 101
 set interface GigabitEthernet0/3
!
access-list 101 permit tcp any any eq 80
```
What is the effect of this configuration?

Accepted Answer

Incoming TCP packets with destination port 80 on G0/2 are forwarded out G0/3, overriding the routing table.. The route-map matches TCP traffic with destination port 80 (HTTP) and sets the output interface to GigabitEthernet0/3. This is applied inbound on GigabitEthernet0/2.

Answer

Outgoing TCP packets with source port 80 on G0/2 are forwarded out G0/3.

Answer

All TCP traffic is forwarded out G0/3 regardless of port.

Answer

The configuration is invalid because 'set interface' cannot be used with a route-map.

Question 5

A network engineer runs the following command to troubleshoot a Route Redistribution issue:

R1# show ip eigrp topology 192.168.10.0/24

And sees the following output:

IP-EIGRP (AS 100): Topology entry for 192.168.10.0/24
  State: Passive, Originating, 1 successors, FD is 128256
  Routing Descriptor Blocks:
  0.0.0.0 (Null0), from 0.0.0.0, Send flag 0x0
      Composite metric is (128256/0), Route is Internal
      Vector metric:
        Minimum bandwidth is 100000 Kbit
        Total delay is 5000 microseconds
        Reliability is 255/255
        Load is 1/255
        Minimum MTU is 1500
        Hop count is 0

What does this output indicate?

Accepted Answer

The route is redistributed into EIGRP from another protocol, such as OSPF or BGP.. The show ip eigrp topology command shows a route that is in Passive state and marked as Originating, with the next hop as 0.0.0.0 (Null0). This indicates that the route is a summary route or a redistributed route that is being originated by this router. The metric 128256 and hop count 0 suggest it is a directly connected or redistributed route.

Answer

The route 192.168.10.0/24 is learned from an EIGRP neighbor.

Answer

The route is a summary route configured on this router.

Answer

The route is a connected interface that is advertised in EIGRP.

Question 6

What is the default behavior of PBR when a 'set ip next-hop' is configured with an IP address that is not directly connected?

Accepted Answer

The packet is dropped.. By default, PBR requires the next-hop to be directly connected. If it is not directly connected, the packet is dropped unless 'set ip next-hop verify-availability' is used or the next-hop is reachable via a recursive lookup (which requires additional configuration).

Answer

The router performs a recursive lookup to find the next-hop.

Answer

The packet is forwarded using the routing table.

Answer

The router sends an ICMP redirect.

Question 7

In Policy-Based Routing (PBR), what is the default action for packets that do not match any route-map sequence?

Accepted Answer

They are forwarded using the normal routing table.. Route-maps have an implicit deny at the end. For PBR, if a packet does not match any permit sequence, it is not policy-routed and is forwarded using the normal routing table.

Answer

They are dropped.

Answer

They are forwarded using the default route.

Answer

They are sent to the next-hop specified in the last sequence.

Question 8

A network engineer runs the following command to troubleshoot an Administrative Distance issue:

R1# show ip route 10.0.0.0 255.0.0.0
Routing entry for 10.0.0.0/8
  Known via "static", distance 1, metric 0
  Redistributing via eigrp 100
  Last update from 10.1.1.2 on GigabitEthernet0/0, 00:00:05 ago
  Routing Descriptor Blocks:
  * 10.1.1.2, from 10.1.1.2, 00:00:05 ago, via GigabitEthernet0/0
      Route metric is 0, traffic share count is 1

What does this output indicate?

Accepted Answer

The route is a static route with administrative distance 1, which is the default for static routes pointing to an interface.. The output shows a static route with administrative distance 1, which is the default for static routes. This route is being redistributed into EIGRP.

Answer

The route is an EIGRP route with administrative distance 90.

Answer

The route is being redistributed from EIGRP into static.

Answer

The route has an administrative distance of 170 because it is external.

Question 9

Which TWO configuration steps are required to enable OSPFv3 on a Cisco IOS router for IPv6 routing? (Choose TWO.)

Accepted Answer

Enable IPv6 unicast routing with 'ipv6 unicast-routing' globally.. You must first enable IPv6 unicast routing globally, then configure the OSPFv3 process and enable it on the interface. The 'network' command is OSPFv2; OSPFv3 uses 'ipv6 ospf' under the interface. The router-id is optional but recommended. The 'ipv6 router ospf' command creates the process.

Answer

Use the 'network' command under the OSPFv3 process to specify interfaces.

Answer

Assign a router-id using 'router-id <A.B.C.D>' under the OSPFv3 process.

Answer

Enable OSPFv3 on the interface using 'ip ospf area '.

Question 10

A multi-router network uses PBR to steer traffic from 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 dropped. Router R1 shows: 'show route-map' indicates the route-map is applied, 'show ip policy' shows the policy on the interface, but 'debug ip policy' shows 'PBR: no route to next-hop 10.10.10.2'. What is the root cause?

Accepted Answer

The next-hop 10.10.10.2 is not reachable, and PBR drops packets when no route to the next-hop exists. Configure a fallback route or use 'set ip default next-hop'.. PBR requires the next-hop to be reachable via a route in the routing table. If the next-hop is not reachable (e.g., due to a routing change or a missing route), PBR will drop the packet unless a fallback is configured. In this case, the next-hop 10.10.10.2 is not reachable, so PBR drops the traffic. The solution is to either ensure the next-hop is reachable or configure a default route or fallback action.

Answer

The ACL in the route-map is incorrectly denying traffic from 172.16.1.0/24, causing PBR to not match the traffic.

Answer

The interface where PBR is applied is in a different VRF, causing the next-hop to be unreachable.

Answer

The next-hop 10.10.10.2 is reachable but the route-map has a 'match ip address' that is too specific, excluding some traffic.

Question 11

A router running EIGRP has a CoPP policy that includes a class-map matching EIGRP packets with a police rate of 2000 bps. The network engineer notices that EIGRP neighbor adjacencies are flapping. The EIGRP network has 100 routes. The engineer checks the CoPP statistics and sees that the EIGRP class has dropped 500 packets in the last hour. What is the most likely root cause?

Accepted Answer

The CoPP police rate of 2000 bps is insufficient for EIGRP hello and update traffic, causing packet drops.. The CoPP police rate of 2000 bps is too low for EIGRP traffic. EIGRP hello packets are sent every 5 seconds (default) and are typically around 60-80 bytes each, plus periodic updates and queries. With 100 routes, the initial exchange and any topology changes generate significant update traffic. Dropping 500 packets in an hour confirms the rate is insufficient, causing hello loss and neighbor flapping.

Answer

The EIGRP hello interval is set too low, causing excessive hello packets that exceed the police rate.

Answer

The EIGRP authentication is causing larger packets that exceed the police rate.

Answer

The CoPP class-map is matching EIGRP packets incorrectly, causing them to be dropped by a default class.

Question 12

A network engineer runs the following command to troubleshoot a Policy-Based Routing (PBR) issue:

R1# show route-map PBR-MAP
route-map PBR-MAP, permit, sequence 10
  Match clauses:
    ip address (access-lists): 101
  Set clauses:
    ip next-hop 10.1.1.2
  Policy routing matches: 50 packets, 6000 bytes

What does this output indicate?

Accepted Answer

PBR is successfully forwarding matching traffic to 10.1.1.2.. The output shows that 50 packets have matched the route-map and have been policy-routed to next-hop 10.1.1.2. This indicates PBR is working.

Answer

The next-hop 10.1.1.2 is not reachable.

Answer

The ACL 101 is misconfigured.

Answer

PBR is not applied to any interface.

Question 13

A network engineer runs the following command to troubleshoot a Policy-Based Routing (PBR) issue:

R1# show ip policy
Interface   Route-map
FastEthernet0/0  PBR-MAP
Serial0/0    PBR-MAP

What does this output indicate?

Accepted Answer

The same route-map is applied to multiple interfaces, which may lead to unintended policy routing.. The output shows that the same route-map PBR-MAP is applied to both FastEthernet0/0 and Serial0/0. This could cause unexpected behavior if the route-map uses interface-specific conditions.

Answer

PBR is applied globally.

Answer

The route-map PBR-MAP is misconfigured.

Answer

PBR is only active on FastEthernet0/0.

Question 14

Which statement about PBR and the 'match ip address' command is correct?

Accepted Answer

It can reference a named or numbered ACL.. The 'match ip address' command references an access-list (standard or extended) to match packets based on source/destination IP addresses.

Answer

It can only match on source IP addresses.

Answer

It can match on MAC addresses.

Answer

It matches packets before routing table lookup.

Question 15

A router is configured with PBR using a route-map that sets the next-hop to 10.0.0.2 for traffic matching ACL 100. The engineer also configures 'set ip default next-hop 10.0.0.3' in the same route-map sequence. Traffic that matches ACL 100 is forwarded to 10.0.0.2, but traffic that does not match ACL 100 is forwarded to 10.0.0.3 only if there is no route in the routing table. However, the engineer expects all unmatched traffic to go to 10.0.0.3 regardless of the routing table. What is the misunderstanding?

Accepted Answer

The 'set ip default next-hop' command overrides the routing table only when no route exists; the engineer wants unconditional forwarding.. The 'set ip default next-hop' command is used only when the packet does not have a matching route in the routing table. If a route exists (even a default route), the packet follows the routing table. The engineer should use 'set ip next-hop' instead of 'set ip default next-hop' to force all unmatched traffic to the next-hop.

Answer

The route-map sequence order is incorrect; the default next-hop should be in a separate sequence.

Answer

The ACL 100 is blocking all traffic, so no traffic matches the set commands.

Answer

The 'set ip default next-hop' command requires a 'set interface' command to work.