300-410 Practice Test 36 — 15 Questions

Question 1

A network engineer is troubleshooting a DMVPN phase 2 network where the hub router is not learning the loopback interface routes from the spokes via EIGRP. The spokes have EIGRP configured on the tunnel interface and are advertising their loopback0 interface. The hub's EIGRP neighbor relationship with the spokes is established. However, the hub's routing table does not contain the loopback routes. The engineer checks the spoke's EIGRP configuration and sees that the loopback interface is not included in any network statement. What is the most likely cause?

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

Accepted Answer

The spoke's EIGRP network statement does not include the loopback subnet.. The hub is not learning the loopback routes because the spoke's EIGRP configuration does not include the loopback subnet in any network statement. EIGRP only advertises interfaces that are explicitly matched by a network command. Since the loopback is not included, it is not advertised to the hub.

Answer

The hub's EIGRP is configured with a distribute-list that filters the loopback routes.

Answer

The tunnel interface on the spoke has 'no ip split-horizon' configured.

Answer

The loopback interface on the spoke is in a different VRF than the tunnel interface.

Question 2

Drag and drop the steps to verify and validate Route Maps and Route Filtering operational state into the correct order, from first to last.

Accepted Answer

Display route-map configuration with show route-map. First, display the route-map configuration and statistics with show route-map. Second, check which route-map is applied to interfaces or routing protocols using show ip policy. Third, verify the filtered prefixes in the BGP table with show ip bgp. Fourth, confirm the impact on routing table entries with show ip route. Finally, test connectivity end-to-end using ping or traceroute.

Question 3

In MPLS, what is the purpose of the TTL propagation feature?

Accepted Answer

It copies the IP TTL into the MPLS TTL at the ingress LER, allowing traceroute to see each hop in the MPLS path.. TTL propagation in MPLS controls whether the IP TTL is copied into the MPLS TTL field at the ingress LER. When enabled (default on Cisco), the ingress copies the IP TTL to the MPLS TTL, and each LSR decrements it. This allows traceroute to reveal each hop in the MPLS core. When disabled, the MPLS TTL is set to 255 and not propagated, hiding the core from traceroute.

Answer

It propagates the MPLS label stack to all routers in the domain.

Answer

It prevents TTL from being decremented in the MPLS core for security purposes.

Answer

It ensures that the MPLS TTL is always equal to the IP TTL at the egress LER.

Question 4

An engineer configures a site-to-site IPsec VPN between two routers using OSPF as the routing protocol. The OSPF neighbor becomes stuck in EXSTART state. The engineer verifies that the IPsec tunnel is up and that both routers can ping each other's tunnel interfaces. What is the most likely cause of the OSPF adjacency issue?

Accepted Answer

The IPsec transform set uses ESP with authentication, adding 22 bytes of overhead, reducing the tunnel MTU to 1478 bytes, causing OSPF DBD packets larger than 1478 bytes to be dropped.. When OSPF neighbors are stuck in EXSTART state, it indicates a problem with Database Description (DBD) packet exchange. With an IPsec tunnel MTU of 1478 bytes (1500 minus 22 bytes for ESP authentication overhead), OSPF DBD packets that exceed this size are fragmented or dropped. Since IPsec does not support fragmentation of encrypted packets, the DBD exchange fails, preventing OSPF from progressing past EXSTART.

Answer

The OSPF network type on the tunnel interface is set to non-broadcast, preventing DBD exchange.

Answer

The OSPF hello and dead intervals are mismatched between the two routers.

Answer

The IPsec tunnel is using transport mode instead of tunnel mode, corrupting OSPF packets.

Question 5

Drag and drop the steps to verify and validate route summarization operational state into the correct order, from first to last.

Accepted Answer

View the routing table for the summary route. Begin by checking the routing table on the summarizing router to see the summary route. Then, inspect the OSPF database to confirm the summary LSA. Next, verify that the summary is not causing suboptimal routing by checking for more specific routes. After that, use show ip protocols to confirm summarization is enabled. Finally, test reachability to a host within the summarized range.

Question 6

Consider the following partial DMVPN configuration on a hub router:

interface Tunnel0
 ip address 10.0.0.1 255.255.255.0
 ip nhrp network-id 100
 ip nhrp authentication cisco123
 tunnel source GigabitEthernet0/0
 tunnel mode gre multipoint
 ip nhrp map multicast dynamic
!

What is the effect of this configuration?

Accepted Answer

The hub will dynamically register spoke NHRP addresses and forward multicast traffic to all registered spokes.. The command 'ip nhrp map multicast dynamic' on the hub allows the hub to dynamically learn the multicast mapping for spokes. This means the hub will forward multicast traffic to all registered spokes that have registered via NHRP. The hub does not require static multicast mappings for each spoke. This is essential for DMVPN phase 2 and 3 where dynamic routing protocols use multicast.

Answer

The hub will only forward multicast traffic to spokes that are statically mapped.

Answer

The hub will not forward multicast traffic at all because dynamic mapping is not supported.

Answer

The hub will use broadcast instead of multicast for all traffic.

Question 7

Which TWO configuration steps are required to implement manual route summarization in OSPF on an ABR? (Choose TWO.)

Accepted Answer

Configure the 'area area-id range network mask' command under router OSPF configuration.. Option A is correct because on an ABR, manual route summarization for inter-area routes is configured with the 'area area-id range network mask' command under router OSPF configuration, which aggregates Type 3 summary LSAs for the specified area's networks. Option B is correct because the summary address must be a supernet that encompasses all the component networks being summarized, ensuring the range covers every prefix it is meant to represent. Option C is wrong because 'summary-address network mask' is used on an ASBR to summarize external routes redistributed into OSPF, not for ABR inter-area summarization. Option D is wrong because 'ip summary-address ospf' is an EIGRP interface command, not an OSPF ABR configuration step. Option E is wrong because a 'network' statement only enables OSPF on matching interfaces; it does not create a summary route.

Answer

Use the 'summary-address network mask' command under router OSPF configuration.

Answer

Apply the 'ip summary-address ospf' command under the interface connecting to the backbone.

Answer

Configure a 'network' statement that matches the summary address.

Question 8

Drag and drop the steps to troubleshoot IPv6 First Hop Security adjacency or connectivity failures into the correct order, from first to last.

Accepted Answer

Ping the next-hop IPv6 address. Start by checking basic connectivity with ping. Then examine the neighbor cache for incomplete entries. Verify if IPv6 snooping is enabled and inspect the binding table. Check RA Guard and DHCPv6 Guard policies that may drop packets. Finally, use debug ipv6 snooping to capture packet drops.

Question 9

A network engineer runs the following command on Router R1:

R1# show ip nhrp nhs
NHS: 172.16.0.1   Tunnel0   status: registered
NHS: 172.16.0.2   Tunnel0   status: not registered

Based on this output, what is the problem?

Accepted Answer

Router R1 is not registered with the second NHS, indicating a registration failure.. The 'show ip nhrp nhs' output lists each Next Hop Server and its registration state. The second NHS (172.16.0.2) shows 'not registered', meaning R1 failed to register with that NHS — typically due to mismatched network-id, missing 'ip nhrp map' entries, or unreachable NHS.

Answer

Both NHS are registered successfully.

Answer

The tunnel interface is down.

Answer

The NHS addresses are swapped.

Question 10

A network engineer runs the following command to troubleshoot a DMVPN spoke not registering with the hub:

R2# debug nhrp

NHRP: Send Registration Request via Tunnel0 10.0.0.2, target 10.0.0.1
NHRP: Receive Registration Reply via Tunnel0 10.0.0.1, src 10.0.0.1, dst 10.0.0.2
NHRP: Registration successful for 10.0.0.2/32 via Tunnel0

What does this output indicate?

Accepted Answer

The spoke has successfully registered its tunnel IP 10.0.0.2/32 with the hub at 10.0.0.1.. The debug output shows the spoke sent a Registration Request to the hub at 10.0.0.1 and received a Registration Reply, followed by 'Registration successful for 10.0.0.2/32 via Tunnel0.' This confirms the NHRP registration completed successfully and the spoke's tunnel IP is now known to the hub. There is no timeout or failure in the output.

Answer

The spoke is unable to reach the hub; the registration request is being sent but no reply is received.

Answer

The spoke is sending a registration request to 10.0.0.1 but the hub is not responding, causing a timeout.

Answer

The spoke is attempting to register with the wrong hub IP address.

Question 11

What is the default DHCPv4 server lease time on a Cisco IOS-XE router configured as a DHCP server?

Accepted Answer

86400 seconds (1 day). The default DHCPv4 lease time on a Cisco IOS-XE router configured as a DHCP server is 86400 seconds (1 day). This is defined in the Cisco IOS DHCP server configuration and is the standard default value used when no lease duration is explicitly specified in the DHCP pool configuration.

Answer

3600 seconds (1 hour)

Answer

43200 seconds (12 hours)

Answer

604800 seconds (7 days)

Question 12

An engineer configures mutual redistribution between OSPF and EIGRP on a PE router in an MPLS L3VPN. The engineer does not configure any route tagging or filtering. After a few minutes, the OSPF and EIGRP domains become unstable, with routes flapping and high CPU usage. What is the most likely explanation?

Accepted Answer

The mutual redistribution creates a routing loop because routes are redistributed back into the original protocol without any loop-prevention mechanism.. Mutual redistribution without route tagging or filtering can cause a routing loop. When OSPF routes are redistributed into EIGRP, and then those EIGRP routes are redistributed back into OSPF, the same prefixes can be learned from both protocols. Without a route tag or a filter to prevent re-redistribution, the router will continuously re-advertise the same routes, causing route flapping and high CPU. This is a classic edge case in redistribution. The solution is to use route tags and filtering to prevent loops.

Answer

The OSPF and EIGRP administrative distances conflict, causing the router to prefer the wrong route.

Answer

The 'default-information originate' command is missing, so the redistributed routes are not advertised.

Answer

The 'subnets' keyword is missing in the OSPF redistribution command, causing only classful routes to be advertised.

Question 13

Drag and drop the steps to troubleshoot a BFD adjacency or connectivity failure into the correct order, from first to last.

Accepted Answer

Verify IP reachability between BFD peers using ping. Start by checking basic IP connectivity to isolate layer 3 issues, then verify BFD parameters match on both sides, inspect BFD session state, check for interface or routing protocol mismatches, and finally enable debug to capture BFD packet exchange.

Question 14

A network engineer runs the following command on Router R1:

R1# show ip dhcp database
URL : flash:/dhcpdb
Read/write : Read/Write
Last updated : Mar 01 2020 00:00:00
Status : Last read succeeded. Next write scheduled in 0 seconds.

Based on this output, which statement is correct?

Accepted Answer

The DHCP database is stored in flash and is functioning correctly.. The output shows the DHCP database is stored in flash (URL: flash:/dhcpdb) with read/write access, and the status indicates the last read succeeded with a write scheduled in 0 seconds. This confirms the database is functioning correctly, as the router can read and write DHCP bindings to flash memory, which is the default storage location for DHCP database persistence.

Answer

The DHCP database is stored in NVRAM and is read-only.

Answer

The DHCP database write failed and needs to be rescheduled.

Answer

The DHCP database is empty because no bindings exist.

Question 15

Which TWO statements about the behavior of administrative distance in Cisco IOS are correct? (Choose TWO.)

Accepted Answer

The default administrative distance for an EIGRP summary route is 5.. Option A is correct because Cisco IOS assigns an EIGRP summary route a default administrative distance of 5, which is lower (more preferred) than internal EIGRP's AD of 90, reflecting the summary's trusted status. Option D is correct because the show ip route command output includes the administrative distance and metric in brackets, e.g., [90/30720], for each route in the routing table. Option B is incorrect because OSPF's default administrative distance is 110, not 90 (90 is internal EIGRP). Option C is incorrect because the distance command under a routing protocol only changes the AD for routes learned by that protocol; it cannot alter connected or static route distances. Option E is incorrect because when two protocols offer routes to the same destination, the route with the lower administrative distance is preferred and installed, not the higher one.

Answer

The default administrative distance for OSPF is 90.

Answer

The distance command applied under a routing protocol can modify the AD for all routes, including connected and static routes, learned via that protocol.

Answer

When two different routing protocols provide routes to the same destination, the route with the higher administrative distance is installed in the routing table.