300-410 Mock Exam 95 — 25 Questions

Question 1

Two routers are configured with EIGRP and have a neighbor relationship. One router has a route to 192.168.1.0/24 with metric 100. The other router has a route to the same prefix with metric 200. An engineer configures an offset-list on the first router to increase the metric of 192.168.1.0/24 by 50, expecting the second router to prefer its own route. Unexpectedly, the second router still prefers the first router's route after the offset. Which is the most likely explanation?

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

Accepted Answer

The offset-list increased the metric from 100 to 150, which is still lower than the second router's metric of 200, so the second router still prefers the first router's route.. The offset-list affects the metric of the route as advertised to the neighbor. However, if the offset-list is applied inbound on the second router, it increases the metric of the received route, making it less preferred. But if the offset-list is applied outbound on the first router, it increases the metric of the route sent to the second router. The second router then compares the received metric (150) with its own metric (200) and still prefers the lower metric (150). The engineer likely applied the offset-list outbound on the first router, but the increase was insufficient to make the second router's route better.

Answer

The offset-list must be applied inbound on the second router to increase the metric of the received route.

Answer

The offset-list command only affects feasible distance, not advertised distance, so the second router ignores it.

Answer

The second router has a higher administrative distance for the route, so it always prefers the first router's route.

Question 2

Which TWO statements about TACACS+ and RADIUS are true? (Choose TWO.)

Accepted Answer

TACACS+ encrypts the entire packet body, including the username and password, using a shared secret.. A is correct because TACACS+ encrypts the entire packet body, including the username and password, using a shared secret. This provides confidentiality for all authentication and authorization data, unlike RADIUS which only encrypts the password field.

Answer

RADIUS encrypts the entire packet payload, including the username and password, using a shared secret.

Answer

TACACS+ uses UDP port 49 by default for communication.

Answer

Both TACACS+ and RADIUS support per-command authorization for exec sessions.

Question 3

A network engineer runs the following command on Router R1:

R1# show ip eigrp interfaces detail GigabitEthernet0/1
IP-EIGRP interfaces for process 100

Xmit Queue   Mean   Pacing Time   Multicast    Pending
Interface        Peers  Un/Reliable  SRTT   Un/Reliable   Flow Timer   Routes
Gi0/1              1       0/0       10       0/10         50           0
  Hello interval is 5 sec
  Next xmit serial <none>
  Un/reliable mcasts: 0/0  Un/reliable ucasts: 0/0
  Mcast exceptions: 0  CR packets: 0  ACKs suppressed: 0
  Retransmissions: 0  Out of sequence: 0
  Authentication mode: none
  Redistribution: redistributed

Based on this output, what is the problem?

Accepted Answer

The 'redistributed' flag indicates that routes are being redistributed into EIGRP on this interface, which is not a standard EIGRP feature.. The output shows 'Redistribution: redistributed' under the interface details, indicating that redistribution is enabled on this interface. However, this is not a standard field in 'show ip eigrp interfaces detail' output; it is likely a custom or misinterpreted output. The problem is that redistribution is applied per interface, but EIGRP redistribution is a global process, not interface-specific. This could cause confusion or misconfiguration.

Answer

The interface is configured for redistribution, which is correct for EIGRP.

Answer

The interface has one EIGRP neighbor, and redistribution is working correctly.

Answer

The output shows that redistribution is enabled, but the interface is not sending hellos.

Question 4

A network administrator notices that SSH access to router R1 from a management station 10.10.10.10 is failing intermittently. R1 has the following configuration: access-list 100 permit tcp 10.10.10.0 0.0.0.255 host 192.168.1.1 eq 22, line vty 0 4 access-class 100 in, and control-plane host control-plane security copp policy-map COPP class MANAGEMENT police cir 8000 bc 1500 conform-action transmit exceed-action drop. The management station is on a different subnet than the management interface. The failure occurs during peak hours. What is the root cause?

Accepted Answer

The CoPP policy is rate-limiting SSH traffic to 8 kbps, and during peak hours, the traffic exceeds this rate, causing drops.. The CoPP policy-map COPP class MANAGEMENT applies a police rate of 8000 bps (8 kbps) with a burst of 1500 bytes to SSH traffic destined for the control plane. During peak hours, the SSH traffic from the management station exceeds this rate, causing packets to be dropped by the exceed-action drop. This intermittent failure aligns with the rate-limiting behavior of CoPP, not with access-list or routing issues.

Answer

The access-class on the VTY lines is incorrectly configured, blocking SSH traffic from the management station.

Answer

The management station is not reachable due to a routing issue.

Answer

The SSH server on R1 has a maximum session limit that is being reached.

Question 5

Which loop prevention mechanism does RIP use to avoid routing loops?

Accepted Answer

Maximum hop count of 15. RIP uses a maximum hop count of 15 to prevent routing loops by ensuring that a route cannot be advertised beyond 15 hops, effectively limiting the propagation of routing information and breaking loops. When a router receives a route with a hop count of 16, it marks the route as unreachable (poison reverse), which stops the loop from continuing. This is a fundamental loop prevention mechanism specific to distance-vector protocols like RIP.

Answer

TTL expiration in IP header

Answer

DUAL algorithm

Answer

LSA aging

Question 6

A network engineer runs the following command to troubleshoot an IPv4 Access Control Lists issue:

R1# debug ip packet 150
IP packet debugging is on for access list 150
*Mar  1 00:25:45.678: IP: s=192.168.1.1 (GigabitEthernet0/0), d=10.1.1.1, len 100, proto UDP, flags 0x0, sport 12345, dport 53, access list 150: matched line 10 permit udp host 192.168.1.1 host 10.1.1.1 eq 53
*Mar  1 00:25:45.679: IP: s=192.168.1.1 (GigabitEthernet0/0), d=10.1.1.1, len 100, proto TCP, flags 0x2, sport 12346, dport 53, access list 150: matched line 20 permit tcp host 192.168.1.1 host 10.1.1.1 eq 53

What does this output indicate?

Accepted Answer

DNS traffic from 192.168.1.1 to 10.1.1.1 is being permitted by ACL 150.. The debug output shows that packets from source 192.168.1.1 to destination 10.1.1.1 with destination port 53 (DNS) are matching permit statements in ACL 150 (line 10 for UDP and line 20 for TCP). Since the ACL is permitting these packets, DNS traffic is allowed through the interface where the ACL is applied.

Answer

DNS traffic from 192.168.1.1 to 10.1.1.1 is being denied by ACL 150.

Answer

ACL 150 is applied outbound on GigabitEthernet0/0.

Answer

ACL 150 has no line 10 or 20.

Question 7

A network engineer is troubleshooting a Cisco router that is configured for RADIUS authentication. The engineer issues 'debug radius authentication' and sees that the RADIUS server is not responding. The router can ping the RADIUS server. What is the most likely cause?

Accepted Answer

UDP port 1812 is blocked between the router and the RADIUS server.. The RADIUS protocol uses UDP port 1812 for authentication. Since the router can ping the RADIUS server, network-layer connectivity exists, but the lack of response in the debug output indicates that the UDP packets are not reaching the server. A firewall or ACL blocking UDP 1812 between the router and the server is the most likely cause, as it prevents the RADIUS request from being received while ICMP (ping) traffic is permitted.

Answer

The RADIUS server shared key is incorrect.

Answer

The router's IP address is not in the RADIUS server's client list.

Answer

The RADIUS server is down.

Question 8

Router R1 and R2 are running OSPF in area 0. R1 has a loopback interface with IP 192.168.1.1/32 advertised into OSPF. R2 learns this route as an intra-area route (AD 110). R2 also runs RIP and learns the same prefix from R3 with AD 120. R2's 'show ip route 192.168.1.1' shows the RIP route. What is the root cause?

Accepted Answer

R2's OSPF process has 'distance 130' configured, making OSPF routes have AD 130, which is higher than RIP's AD 120.. RIP has AD 120, OSPF has AD 110, so OSPF should be preferred. If the OSPF route is not installed, it could be due to a higher metric or a filter. The correct answer is that the OSPF route is an external route (type-5) because it was redistributed from another protocol, not an intra-area route. The scenario says intra-area, but if the loopback is not directly connected to OSPF (e.g., it is in a different VRF), it might be redistributed as external. The question states it is advertised into OSPF, but the AD for external is 110, same as intra-area. The trick is that the OSPF route might have a higher metric than the RIP route, but AD is checked first. The most likely cause is that the OSPF route is not in the routing table due to a distribute-list or because the OSPF process has 'distance 130' configured for all routes.

Answer

The RIP route has a better metric than the OSPF route.

Answer

R2 has a static route with AD 1 that overrides both.

Answer

The OSPF route is an external route with AD 170 due to redistribution.

Question 9

Which TWO configuration steps are required to change the administrative distance for routes learned from a specific neighbor in EIGRP? (Choose TWO.)

Accepted Answer

Configure a prefix list to match the routes from the neighbor.. To change the AD for routes from a specific EIGRP neighbor, you must first configure a prefix list to match the routes, then apply it using the distance command in EIGRP router configuration mode. The distance command can specify a different AD for routes matching a prefix list from a specific neighbor.

Answer

Use the distance eigrp command in router configuration mode.

Answer

Configure an access list to permit the routes from the neighbor.

Answer

Use the redistribute command to change the administrative distance.

Question 10

An engineer configures IPv6 uRPF strict mode on an interface of a router that participates in OSPFv3. The router starts dropping OSPFv3 Hello packets received on that interface, causing the OSPFv3 neighbor adjacency to fail. Which is the most likely explanation?

Accepted Answer

The OSPFv3 Hello packets have a source IPv6 address that is not in the routing table, causing uRPF strict mode to drop them.. IPv6 uRPF strict mode checks that the source IPv6 address of an incoming packet matches a route in the routing table and that the incoming interface is the same as the outgoing interface for that route. OSPFv3 Hello packets are sent with the link-local address of the sending interface as the source IPv6 address. If that link-local address is not present in the IPv6 routing table (e.g., because OSPFv3 has not yet installed the neighbor's link-local route), uRPF strict mode drops the packet, preventing the adjacency from forming.

Answer

The OSPFv3 Hello packets are multicast to ff02::5, and uRPF strict mode drops all multicast traffic by default.

Answer

The OSPFv3 Hello packets have a hop limit of 1, and uRPF strict mode requires a hop limit of at least 2.

Answer

The interface has IPv6 unicast-routing disabled, which prevents uRPF from functioning correctly.

Question 11

Router R1 and R2 are running EIGRP as the IGP, and R1 is redistributing a connected subnet 10.1.1.0/24 into EIGRP. R2 also runs BGP with an external peer, and BGP is redistributing the same prefix 10.1.1.0/24 into EIGRP with a route-map that sets the administrative distance to 100. On R3, a downstream EIGRP router, 'show ip route 10.1.1.0' shows the route via R2. What is the most likely cause of suboptimal routing?

Accepted Answer

The internal EIGRP route is not present in R3's routing table due to a distribute-list inbound from R1, so the redistributed route with AD 100 is the only path.. EIGRP internal routes have AD 90, external routes AD 170. Redistribution from BGP into EIGRP creates external routes (AD 170) unless a route-map changes the distance. Setting AD to 100 makes the redistributed route preferred over the original internal route (AD 90) because 100 > 90, so the internal route should be preferred. However, if the internal route is not present due to a filter, or if the distance is set lower than 90, the redistributed route is chosen. The correct answer is that the route-map set distance 100 is higher than 90, so the internal route (AD 90) is still preferred; the issue is that the internal route is being suppressed by a distribute-list on R3.

Answer

The route-map set distance 100 overrides the default AD, making the redistributed route preferred over the internal route (AD 90).

Answer

The redistributed route has AD 170 by default, and the route-map is ignored because redistribution from BGP always uses AD 170.

Answer

R3 prefers routes with lower metric, not AD, and the redistributed route has a better metric.

Question 12

A network engineer runs the following command on Router R8:

R8# show ip route 10.2.2.0
Routing entry for 10.2.2.0/24
  Known via "eigrp 100", distance 90, metric 28160
  Redistributing via eigrp 100
  Last update from 192.168.2.1 on GigabitEthernet0/0, 00:00:05 ago
  Routing Descriptor Blocks:
  * 192.168.2.1, from 192.168.2.1, 00:00:05 ago, via GigabitEthernet0/0
      Route metric is 28160, traffic share count is 1

R8 also has a static route to 10.2.2.0/24 with next-hop 192.168.3.1 configured with distance 95. Which route will be used?

Accepted Answer

The EIGRP route will be used because it has a lower administrative distance.. The EIGRP route has a distance of 90, which is lower than the static route's distance of 95. Therefore, the EIGRP route will be preferred and installed in the routing table.

Answer

The static route will be used because it is manually configured.

Answer

Both routes will be used for load balancing.

Answer

Neither route will be used due to a routing loop.

Question 13

Which THREE statements about administrative distance are true when comparing OSPF and EIGRP? (Choose THREE.)

Accepted Answer

By default, EIGRP internal routes are preferred over OSPF routes.. OSPF has a default AD of 110, EIGRP internal routes have 90, and EIGRP external routes have 170. Therefore, EIGRP internal routes are preferred over OSPF, but OSPF is preferred over EIGRP external routes. Administrative distance can be manually changed for either protocol.

Answer

EIGRP internal routes have a default administrative distance of 170.

Answer

OSPF external routes have a default administrative distance of 110.

Question 14

A network engineer runs the following command to troubleshoot a Device Access Control issue:

R1# show policy-map control-plane input class class-default

Class-map: class-default (match-any)
    140225 packets, 12345678 bytes
    5 minute offered rate 1000 bps, drop rate 0 bps
    Match: any
    police:
        cir 1000000 bps, bc 31250 bytes
        conformed 140225 packets, 12345678 bytes; actions:
          transmit
        exceeded 0 packets, 0 bytes; actions:
          drop
        violated 0 packets, 0 bytes; actions:
          drop

What does this output indicate?

Accepted Answer

The CoPP policy is policing traffic to 1 Mbps, and all traffic so far has been within the limit and transmitted.. The output shows that the class-default class in the CoPP policy has a police configuration with a CIR of 1,000,000 bps (1 Mbps). All 140,225 packets have been counted as conforming, with zero exceeded or violated packets, and the conform action is 'transmit'. This means all traffic has been within the policed rate and has been forwarded without drops.

Answer

The CoPP policy is dropping all traffic because the CIR is too low.

Answer

The CoPP policy is not matching any traffic because the class-default does not match any packets.

Answer

The CoPP policy is only policing traffic that exceeds the CIR, but all traffic is being transmitted.

Question 15

Which THREE statements about route redistribution and administrative distance are true? (Choose THREE.)

Accepted Answer

EIGRP external routes (redistributed) have a default administrative distance of 170.. Administrative distance (AD) is crucial in redistribution because it determines which routes are preferred when multiple protocols learn the same prefix. Option A is correct: EIGRP has a default AD of 90 for internal routes and 170 for external (redistributed) routes. Option B is correct: OSPF external routes have a default AD of 110, same as internal OSPF routes, but can be changed. Option C is correct: Changing AD can influence route selection and help prevent routing loops. Option D is incorrect: The distance command can be applied to both internal and external routes. Option E is incorrect: RIP has a default AD of 120, which is higher than OSPF's 110, so OSPF is preferred.

Answer

The 'distance' command in OSPF can only be applied to external routes, not internal routes.

Answer

When redistributing RIP into OSPF, the redistributed routes will have a lower administrative distance than OSPF internal routes.

Question 16

A network engineer runs the following command to verify MPLS L3VPN operation:

R1# show mpls ldp bindings

Output:
  lib entry: 10.1.1.0/24, rev 2
        local binding:  label: 101
        remote binding: lsr: 10.0.0.2:0, label: 201
  lib entry: 10.2.2.0/24, rev 4
        local binding:  label: 102
        remote binding: lsr: 10.0.0.2:0, label: 202
  lib entry: 10.3.3.0/24, rev 6
        local binding:  label: 103
        remote binding: lsr: 10.0.0.2:0, label: imp-null

What does this output indicate?

Accepted Answer

The router has learned labels for three prefixes from LSR 10.0.0.2. The show mpls ldp bindings command displays the Label Information Base (LIB) entries. Each entry shows a prefix, the local label assigned by this router, and the remote label learned from a specific LSR (10.0.0.2). The third entry shows 'imp-null' for the remote label, meaning the neighbor is using implicit null (label 3) for that prefix, typically for BGP-free core or PHP.

Answer

The router is using MPLS TE

Answer

The router is a route reflector

Answer

The router has a label for 10.3.3.0/24 that is implicit null

Question 17

Which TWO commands would a network engineer use to verify the results of route redistribution from OSPF into EIGRP? (Choose TWO.)

Accepted Answer

show ip route eigrp. To verify redistribution, you can check the routing table to see if redistributed routes appear, and you can check the EIGRP topology table to see if they are learned via redistribution. Option A is correct because 'show ip route eigrp' displays EIGRP routes, including redistributed ones. Option D is correct because 'show ip eigrp topology' shows all EIGRP routes and their sources. Option B is incorrect because 'show ip ospf database' shows OSPF LSAs, not redistributed routes. Option C is incorrect because 'show ip protocols' shows routing protocol parameters but not specific redistributed routes. Option E is incorrect because 'show ip eigrp traffic' shows packet statistics, not route information.

Answer

show ip ospf database

Answer

show ip protocols

Answer

show ip eigrp traffic

Question 18

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

R1# show ip eigrp topology 192.168.3.0/24 all-links
IP-EIGRP (AS 100): Topology entry for 192.168.3.0/24
  State is Passive, Query origin flag is 1, 1 Successor(s), FD is 30720
  Routing Descriptor Blocks:
  10.1.1.2 (GigabitEthernet0/0), from 10.1.1.2, Send flag is 0x0
      Composite metric is (30720/28160), Route is Internal
      Vector metric:
        Minimum bandwidth is 100000 Kbit
        Total delay is 2000 microseconds
        Reliability is 255/255
        Load is 1/255
        Minimum MTU is 1500
        Hop count is 1
  10.1.2.2 (GigabitEthernet0/1), from 10.1.2.2, Send flag is 0x0
      Composite metric is (30720/28160), Route is Internal
      Vector metric:
        Minimum bandwidth is 100000 Kbit
        Total delay is 2000 microseconds
        Reliability is 255/255
        Load is 1/255
        Minimum MTU is 1500
        Hop count is 1

What does this output indicate?

Accepted Answer

Both paths are feasible successors and will be used for load balancing.. The output shows two equal-cost paths to the same network, both with the same composite metric and FD. This indicates that EIGRP is load balancing across these two links, but the administrative distance is not directly shown here; it's about the topology table.

Answer

Only the first path is used because it has a lower administrative distance.

Answer

The second path is a feasible successor but not used because the first path has a better metric.

Answer

The output indicates a routing loop because there are two paths with the same metric.

Question 19

An engineer configures an IPv6 ACL to filter OSPFv3 traffic on a router interface. The ACL includes a deny entry for OSPFv3 (protocol 89) followed by a permit ipv6 any any. However, OSPFv3 adjacencies still fail to form over that interface. Which is the most likely explanation?

Accepted Answer

The ACL is applied outbound, but OSPFv3 packets are generated locally and are not subject to outbound ACL filtering.. OSPFv3 packets are generated by the router's own control plane (the OSPF process) and are not subject to outbound ACL filtering on the interface. Outbound ACLs only filter packets that are being forwarded through the interface, not packets originated by the router itself. Since the ACL is applied outbound, the deny entry for protocol 89 never applies to locally generated OSPFv3 hello packets, so they are sent out, but the inbound side of the neighbor might still be blocked or the adjacency fails due to other reasons—but the core issue here is that outbound ACLs do not filter locally originated traffic.

Answer

The ACL uses 'deny ospf' but OSPFv3 uses protocol 89, which is not matched by 'deny ospf' in IPv6 ACLs.

Answer

The ACL must include a permit entry for the link-local address of the neighbor, otherwise OSPFv3 packets are dropped.

Answer

The ACL is applied to the interface but the router has 'ipv6 ospf authentication' configured, which changes the packet format and bypasses ACL filtering.

Question 20

An engineer configures Control Plane Policing (CoPP) with a policy map that includes a class-map matching BGP traffic. The policy map has a 'police' action that sets the rate-limit in bps. After applying the policy to the control plane, BGP sessions start flapping. Which is the most likely explanation?

Accepted Answer

The police rate is configured in bps, but BGP keepalives are small packets; pps should be used to avoid dropping.. CoPP rate-limits are often configured in bps by default, but for control plane traffic, pps (packets per second) is more appropriate. If the rate-limit is set in bps, it may be too low for BGP keepalive packets, which are small. The edge case is that the engineer used bps instead of pps, causing the policer to drop BGP packets.

Answer

The class-map matches BGP traffic incorrectly; it should match on protocol BGP.

Answer

The policy map is applied to the control plane inbound, but BGP packets are sent outbound.

Answer

The default class is not configured, causing all other traffic to be dropped.