300-410 Practice Test 37 — 15 Questions

Question 1

Which BGP loop prevention mechanism relies on the AS_PATH attribute?

Accepted Answer

AS_PATH loop detection. BGP's primary loop prevention mechanism is AS_PATH loop detection: when a router receives an UPDATE, it checks whether its own AS number appears in the AS_PATH attribute. If it does, the route is rejected as a loop. This works because each AS prepends its AS number when advertising routes to eBGP peers, so a route that has traversed an AS will carry that AS in the path.

Answer

Split horizon

Answer

TTL expiration

Answer

Route poisoning

Question 2

Drag and drop the steps for troubleshooting MPLS operations adjacency or connectivity failures into the correct order, from first to last.

Accepted Answer

Verify LDP neighbor state with show mpls ldp neighbor. Start by verifying LDP neighbor state, then check interface MPLS enablement, inspect label bindings, test end-to-end LSP connectivity, and finally validate TTL propagation for troubleshooting.

Question 3

What is the default maximum number of labels that can be imposed in the MPLS label stack on a Cisco IOS-XE router?

Accepted Answer

6 labels. The default maximum label stack depth is 6 labels on Cisco IOS-XE routers, though this can be increased with the 'mpls label range' command.

Answer

3 labels

Answer

10 labels

Answer

Unlimited

Question 4

What is the default role of an interface in IPv6 Neighbor Discovery Inspection when no policy is explicitly applied?

Accepted Answer

Untrusted. In IPv6 Neighbor Discovery Inspection (NDI), an interface is considered untrusted by default when no policy is explicitly applied. This default ensures that all incoming Neighbor Discovery (ND) messages are subject to validation against the binding table, preventing attacks such as Neighbor Advertisement spoofing and Duplicate Address Detection (DAD) exploitation. Only interfaces explicitly configured with a trust policy bypass this inspection.

Answer

Trusted

Answer

Server

Answer

Host

Question 5

What is the maximum number of IPv6 over IPv4 tunnels that can be configured on a Cisco IOS router?

Accepted Answer

Platform-dependent, no fixed maximum.. C is correct because the maximum number of IPv6 over IPv4 tunnels on a Cisco IOS router is platform-dependent and limited by available system resources such as CPU and memory, not by a fixed software limit. Cisco IOS does not impose a hard-coded maximum; the actual number depends on the router model, the type of tunnel (e.g., manual, 6to4, ISATAP, GRE), and the configuration complexity.

Answer

256

Answer

1024

Answer

64

Question 6

A network engineer runs the following command on Router R1:

R1# show ip sla statistics
IPSLAs Latest Statistics:

Round Trip Time (RTT) for Index 1
   Latest RTT: 10 ms
   Latest RTT (milliseconds): 10
   Number of successes: 100
   Number of failures: 0
   Operation time to live: 3000
   Operation frequency: 60 seconds
   Next operation start time: 00:00:45

Based on this output, what is the status of the IP SLA operation?

Accepted Answer

The IP SLA operation is successful and has a low RTT.. The output shows 100 successes and 0 failures, with a latest RTT of 10 ms, indicating the IP SLA operation is functioning correctly and with low latency. The 'Number of successes: 100' confirms the operation has been consistently successful, and the low RTT value reflects good network performance.

Answer

The IP SLA operation has failed 100 times.

Answer

The IP SLA operation is not configured correctly.

Answer

The IP SLA operation is about to expire.

Question 7

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

R1# show ip sla statistics 10 detail

Round Trip Time (RTT) for Index 10
   Latest RTT: 12 ms
   Latest RTT (milliseconds): 12
   Latest RTT (microseconds): 12000
   Last operation start time: 12:34:56.789 UTC Mon Mar 1 2021
   Last operation return code: OK
   Number of successes: 100
   Number of failures: 0
   Operation time to live: Forever
   Last operation response time: 12 ms
   Latest operation start time: 12:34:56.789 UTC Mon Mar 1 2021
   Latest operation return code: OK
   Over thresholds occurred: FALSE
   Threshold (milliseconds): 5000
   RTT Values:
      RTTAvg: 12
      RTTMin: 10
      RTTMax: 15
      RTTNum: 100
      RTTStdDev: 1

What does this output indicate?

Accepted Answer

The IP SLA operation shows stable performance with low jitter and no threshold violations.. The output shows stable performance with low jitter (standard deviation of 1 ms) and no threshold violations (over thresholds occurred: FALSE, threshold is 5000 ms). The number of failures is 0, indicating no packet loss.

Answer

The IP SLA operation has high jitter because the RTT standard deviation is 1 ms.

Answer

The IP SLA operation is experiencing packet loss because the number of failures is 0.

Answer

The IP SLA operation has exceeded the threshold because the RTTMax is 15 ms.

Question 8

Drag and drop the steps to verify and validate the MPLS L3VPN operational state into the correct order, from first to last.

Accepted Answer

Display VRF routing table for CE routes. Start by checking the VRF routing table with 'show ip route vrf ' to confirm CE routes are present. Then verify that VPNv4 routes are installed using 'show bgp vpnv4 unicast all'. Next, confirm the MPLS forwarding entry for a specific prefix with 'show mpls forwarding-table'. After that, test end-to-end connectivity with a ping from the CE to a remote CE. Finally, validate that the label stack is correctly imposed using 'show ip cef vrf '.

Question 9

Drag and drop the steps to troubleshoot an MPLS L3VPN adjacency or connectivity failure into the correct order, from first to last.

Accepted Answer

Check PE-CE BGP adjacency state. Troubleshooting begins by verifying the PE-CE adjacency with 'show ip bgp vpnv4 vrf <name> summary'. If the adjacency is down, check the VRF interface status and IP connectivity using ping. Then verify that the VRF is correctly configured with 'show vrf'. Next, confirm that the MPLS LSP to the remote PE is functional using 'show mpls lsp'. Finally, check that the VPNv4 routes are being exchanged between PEs with 'show bgp vpnv4 unicast all'.

Question 10

A network engineer runs the following command to troubleshoot a VRF-Lite DMVPN issue:

R1# show ip nhrp vrf CUSTOMER_G detail

Output:
10.6.6.1/32 via 10.6.6.1, Tunnel0 created 00:01:00, expire 01:59:00
  Type: dynamic, Flags: used
  NBMA address: 192.168.1.1
  (no-socket)
  Registration handle: 0x00000001
  Cache entries: 1

What does this output indicate?

Accepted Answer

The NHRP mapping for 10.6.6.1 is dynamic, with NBMA address 192.168.1.1, and is actively used.. The 'show ip nhrp vrf detail' command displays NHRP cache entries for a specific VRF. The output shows a dynamic NHRP mapping for destination 10.6.6.1/32, with NBMA address 192.168.1.1, learned via Tunnel0. The entry was created 1 minute ago and will expire in 1 hour 59 minutes. The 'used' flag indicates the mapping is actively being used.

Answer

The NHRP mapping is static and was manually configured.

Answer

The NHRP mapping has expired and needs to be refreshed.

Answer

The NHRP mapping is for a multicast group address.

Question 11

Which statement accurately describes the default behavior of auto-summary in EIGRP on Cisco IOS-XE?

Accepted Answer

Auto-summary is disabled by default, and EIGRP advertises subnets without automatic summarization.. In Cisco IOS-XE, EIGRP auto-summary is disabled by default. This means that EIGRP advertises subnets without automatically summarizing them at classful boundaries, allowing for more granular route advertisement and preventing routing issues in discontiguous networks.

Answer

Auto-summary is enabled by default, causing EIGRP to summarize at classful boundaries.

Answer

Auto-summary is enabled by default but only for external routes.

Answer

Auto-summary is disabled by default unless the network is configured with a classful mask.

Question 12

A network engineer runs the following command on Router R1:

R1# show route-map TEST
route-map TEST, permit, sequence 10
  Match clauses:
    ip address (access-lists): 10
  Set clauses:
    metric 50
route-map TEST, deny, sequence 20
  Match clauses:
    ip address (access-lists): 20
  Set clauses:

Based on this output, what is the effect of this route-map when applied to a redistribution command?

Accepted Answer

Routes matching ACL 10 are redistributed with metric 50; routes matching ACL 20 are denied; all other routes are also denied.. Route-map TEST processes sequences in order. Sequence 10 permits routes matching ACL 10 and sets their metric to 50. Sequence 20 denies routes matching ACL 20. Since there is no explicit permit for other routes, the implicit deny at the end of the route-map denies all unmatched routes. Thus, only routes matching ACL 10 are redistributed with metric 50.

Answer

All routes are redistributed with metric 50.

Answer

Routes matching ACL 20 are redistributed with default metric.

Answer

The route-map has no effect because set clauses are missing in sequence 20.

Question 13

A network engineer is troubleshooting an IPsec site-to-site VPN between two routers. The tunnel interface is up/up, but traffic from the local LAN to the remote LAN is not passing. The engineer checks the crypto map and sees it is applied to the outside interface. What is the most likely cause of the traffic failure?

Accepted Answer

The access list in the crypto map does not match the LAN-to-LAN traffic.. The crypto map's access list (the 'match address' ACL) defines which traffic is considered interesting and therefore encrypted/tunneled. If the tunnel is up/up but LAN-to-LAN traffic isn't passing, the most common cause is that the ACL doesn't match the actual source/destination subnet pairs, so the router either doesn't encrypt the traffic or drops it as non-interesting. The tunnel interface being up only confirms IKE/IPsec SA establishment, not that the correct traffic is being selected.

Answer

The crypto map is not applied to the tunnel interface.

Answer

The IPsec transform set is missing the esp-aes encryption algorithm.

Answer

The IKE phase 1 proposal is mismatched between the two routers.

Question 14

What is the default OSPF network type for a serial interface configured with HDLC encapsulation on Cisco routers?

Accepted Answer

Point-to-point. On Cisco routers, a serial interface using HDLC encapsulation defaults to the OSPF network type point-to-point. This is because HDLC is a synchronous framing protocol that inherently implies a direct, single-neighbor link, so OSPF automatically sets the network type to point-to-point, which requires no DR/BDR election and uses multicast Hello packets (224.0.0.5).

Answer

Broadcast

Answer

Non-broadcast (NBMA)

Answer

Point-to-multipoint

Question 15

Which THREE symptoms indicate a potential issue with NHRP registration in a DMVPN network? (Choose THREE.)

Accepted Answer

The spoke router does not receive an NHRP Registration Reply from the hub.. Option A is correct because a spoke initiates NHRP registration by sending an NHRP Registration Request to the hub's NBMA address, and the hub must respond with an NHRP Registration Reply; failure to receive that reply directly indicates the registration exchange is failing. Option B is correct because a successful registration causes the hub to install an NHRP cache entry mapping the spoke's tunnel IP to its NBMA address, so a missing entry confirms the spoke never successfully registered. Option C is correct because the tunnel interface can be UP/UP (mGRE is stateless and comes up regardless of NHRP), yet the NHRP registration status explicitly showing 'NOT REGISTERED' is a direct symptom of an NHRP registration problem. Option D is not correct because an UP/DOWN tunnel interface points to a Layer 1/2 or tunnel source/destination reachability problem rather than an NHRP registration failure. Option E is not correct because routes learned from the hub indicate that routing adjacencies and reachability are working, which is not a symptom of failed NHRP registration.

Answer

The spoke router's tunnel interface shows 'UP/DOWN'.

Answer

The spoke router's routing table shows routes learned from the hub.