300-410 Mock Exam 77 — 25 Questions

Question 1

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

R1# show ip sla monitor configuration 10

IP SLAs Monitor, Infrastructure Engine-II.
Entry number: 10
Owner: 
Tag: 
Type of operation to perform: icmp-echo
Target address: 192.168.1.1
Type Of Service parameter: 0x0
Request size (ARR data portion): 28
Operation timeout (milliseconds): 5000
Frequency (seconds): 60
Next Scheduled Start Time: Start Time already occurred
Group Scheduled : FALSE
Life (seconds): Forever
Entry Ageout (seconds): never
Recurring (Starting Everyday): FALSE
Status of entry (SNMP RowStatus): Active
Threshold (milliseconds): 5000
Distribution Statistics:
   Number of history intervals kept: 0
   Number of history buckets kept: 15
   History Statistics:
      Number of history Lives kept: 0

What does this output indicate?

Accepted Answer

The IP SLA monitor operation is configured as an ICMP echo probe with a 60-second frequency and 5-second timeout.. This is the older 'ip sla monitor' configuration output, identical to 'ip sla configuration'. It shows an ICMP echo probe to 192.168.1.1, active status, 60-second frequency, and 5-second timeout.

Answer

The IP SLA monitor operation is configured as a UDP jitter probe to 192.168.1.1.

Answer

The IP SLA monitor operation has a frequency of 5 seconds and a timeout of 60 seconds.

Answer

The IP SLA monitor operation is in a 'Pending' state.

Question 2

What is the default threshold value (in milliseconds) for an IP SLA operation?

Accepted Answer

5000 ms. The default threshold for an IP SLA operation is 5000 milliseconds (5 seconds). This is the value above which the operation is considered to have exceeded a tolerable delay, triggering reaction conditions.

Answer

1000 ms

Answer

10000 ms

Answer

No default threshold

Question 3

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

R1# debug ip routing
IP routing debugging is on
*Mar  1 00:01:23.456: RT: add 192.168.2.0/24 via 10.1.1.2, eigrp metric [170/30720]
*Mar  1 00:01:23.456: RT: closer admin distance for 192.168.2.0, adding to routing table
*Mar  1 00:01:23.456: RT: add 192.168.2.0/24 via 10.1.1.2, ospf metric [110/20]
*Mar  1 00:01:23.456: RT: not add 192.168.2.0/24 via 10.1.1.2, ospf metric [110/20] - route already in table with better admin distance

What does this output indicate?

Accepted Answer

The EIGRP route remains in the routing table because its administrative distance was manually changed to 100, making it better than OSPF's 110.. The debug shows that the EIGRP route (AD 170) is added first, but then OSPF (AD 110) tries to add the same route. Since OSPF has a lower AD, it replaces the EIGRP route. The output indicates that the route from OSPF is preferred due to lower administrative distance.

Answer

The EIGRP route is preferred because it was added first.

Answer

The OSPF route is preferred because it has a lower administrative distance of 110 compared to EIGRP's 170.

Answer

Both routes are added to the routing table, and load balancing occurs.

Question 4

What is the default administrative distance for a route learned via the Enhanced Interior Gateway Routing Protocol (EIGRP) summary route?

Accepted Answer

5. EIGRP summary routes have a default administrative distance of 5, which is lower than the standard EIGRP internal distance of 90 and EIGRP external distance of 170.

Answer

90

Answer

170

Answer

1

Question 5

A network engineer is troubleshooting a route summarization issue in a network using RIP. Router R1 is configured with the 'ip summary-address rip 192.168.0.0 255.255.252.0' command on its serial interface. After the configuration, R2, which is connected via that interface, can no longer reach the 192.168.1.0/24 subnet, although other subnets within the summary are reachable. What is the most likely cause?

Accepted Answer

The 192.168.1.0/24 subnet is not included in the summary range because the summary mask is /22, but the subnet's network address is 192.168.1.0, which is within the range, but the RIP process may have a split-horizon issue preventing the route from being advertised.. In RIP, the summary-address command suppresses the advertisement of more specific routes. However, if the summary route is not installed in the routing table (e.g., due to a metric issue), the specific routes may still be suppressed, causing loss of connectivity.

Answer

The 192.168.1.0/24 subnet is not directly connected to R1, so it cannot be summarized.

Answer

The summary route 192.168.0.0/22 is being advertised with a higher metric than the specific routes, causing R2 to prefer a different path.

Answer

The summary address command was applied on the wrong interface, causing the summary to be sent out all interfaces, including the one facing the 192.168.1.0/24 subnet's origin.

Question 6

A network engineer runs the following command on Router R1:

R1# show ip route 172.16.0.0 255.255.240.0

Routing entry for 172.16.0.0/20
  Known via "ospf 1", distance 110, metric 20, type intra area
  Last update from 192.168.1.2 on GigabitEthernet0/0, 00:00:15 ago
  Routing Descriptor Blocks:
  * 192.168.1.2, from 192.168.1.2, 00:00:15 ago, via GigabitEthernet0/0
      Route metric is 20, traffic share count is 1

Based on this output, what can be concluded about the route 172.16.0.0/20?

Accepted Answer

The route is an inter-area summary route.. The OSPF route is learned via intra-area (type intra area) with a metric of 20, which is characteristic of a summary LSA type 3, but the output shows intra area, indicating it is a summary route from an ABR.

Answer

The route is a default route.

Answer

The route is an external route.

Answer

The route is a connected route.

Question 7

In OSPF, what is the default metric for a Type 3 summary LSA generated by an ABR using the 'area range' command?

Accepted Answer

The lowest metric among the summarized routes.. The default metric for a Type 3 summary LSA is the lowest metric among the component routes being summarized.

Answer

The highest metric among the summarized routes.

Answer

The sum of all metrics.

Answer

The metric is set to 1 by default.

Question 8

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 9

An engineer configures route redistribution from EIGRP into OSPF. The redistributed routes appear in the OSPF database but are not installed in the routing table of other OSPF routers. Which is the most likely explanation?

Accepted Answer

The redistributed routes have a metric of 0, which OSPF treats as unreachable.. When redistributing into OSPF, a seed metric must be specified. If not, OSPF defaults to a metric of 20 for external type 2 routes, but if the metric-type is set to 1, the default metric is 0, which may cause the route to be considered unreachable or not installed.

Answer

The OSPF process on the redistributing router does not have a router-id configured.

Answer

The administrative distance of OSPF external routes (110) is higher than EIGRP (90), so the EIGRP routes are preferred.

Answer

The redistribute command is missing the subnets keyword, causing only classful routes to be redistributed.

Question 10

In EIGRP, what is the default administrative distance of a summary route created with the 'ip summary-address eigrp' command?

Accepted Answer

5. By default, EIGRP summary routes have an administrative distance of 5, which is lower than the default distance of 90 for internal EIGRP routes.

Answer

90

Answer

170

Answer

1

Question 11

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

R1# show ip ospf interface detail GigabitEthernet0/0
GigabitEthernet0/0 is up, line protocol is up
  Internet Address 10.1.1.1/24, Area 0, Attached via Network Statement
  Process ID 1, Router ID 1.1.1.1, Network Type BROADCAST, Cost: 1
  Topology-MTID    Cost    Disabled    Shutdown      Topology Name
        0           1        no          no            Base
  Transmit Delay is 1 sec, State DR, Priority 1
  Designated Router (ID) 1.1.1.1, Interface address 10.1.1.1
  Backup Designated router (ID) 2.2.2.2, Interface address 10.1.1.2
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    oob-resync timeout 40
    Hello due in 00:00:03
  Supports Link-local Signaling (LLS)
  Cisco NSF helper support enabled
  IETF NSF helper support enabled
  Can be protected by per-prefix Loop-Free Fast Reroute
  Can be used for per-prefix Loop-Free Fast Reroute remote-LFA tunnels
  Index 1/1/1, flood queue length 0
  Next 0x0(0)/0x0(0)/0x0(0)
  Last flood scan length is 1, maximum is 1
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 1, Adjacent neighbor count is 1
    Adjacent with neighbor 2.2.2.2  (Backup Designated Router)
  Suppress hello for 0 neighbor(s)

What does this output indicate?

Accepted Answer

The interface is an OSPF broadcast interface with a cost of 1, and the router is the Designated Router.. The output shows detailed OSPF interface information, including the cost, timers, and neighbor state. It does not directly show administrative distance, but it is relevant for understanding OSPF operation.

Answer

The interface has an administrative distance of 110.

Answer

The neighbor 2.2.2.2 is not fully adjacent because it is a backup designated router.

Answer

The OSPF process ID is 100.

Question 12

What is the default administrative distance for a route learned via the Routing Information Protocol (RIP)?

Accepted Answer

120. RIP routes have a default administrative distance of 120.

Answer

100

Answer

110

Answer

130

Question 13

Drag and drop the steps to troubleshoot suboptimal routing due to incorrect Administrative Distance values into the correct order, from first to last.

Accepted Answer

Examine the routing table for the destination prefix. The correct order begins by identifying the routing table entries to see which routes are preferred, then checking the AD values of the competing protocols, verifying the configuration of the protocol with the lower AD, adjusting the AD on the desired protocol to make it preferred, and finally confirming the routing table update.

Question 14

An engineer enables uRPF (strict mode) on an interface facing the Internet. Legitimate traffic from a customer network is being dropped. The customer network uses asymmetric routing where return traffic takes a different path. Which is the most likely explanation?

Accepted Answer

The uRPF strict mode requires that the source IP's best path is out the same interface; asymmetric routing violates this.. Strict uRPF checks that the source IP of incoming packets has a route in the FIB pointing back to the same interface. With asymmetric routing, the return path may use a different interface, causing the check to fail and the packet to be dropped.

Answer

The uRPF loose mode should be used instead, as it only requires a route to the source IP in the FIB.

Answer

The customer network is using private IP addresses that are not routable.

Answer

The uRPF allow-default option is missing, which is required for default routes.

Question 15

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

R1# debug ip sla monitor trace

IP SLAs Monitor trace debugging is on

*Mar  1 12:34:56.789: IP SLAs Monitor: Starting operation 10
*Mar  1 12:34:56.789: IP SLAs Monitor: Sending ICMP echo request to 192.168.1.1
*Mar  1 12:34:56.790: IP SLAs Monitor: Received ICMP echo reply from 192.168.1.1
*Mar  1 12:34:56.790: IP SLAs Monitor: RTT = 12 ms
*Mar  1 12:34:56.790: IP SLAs Monitor: Operation 10 completed successfully
*Mar  1 12:35:56.789: IP SLAs Monitor: Starting operation 10
*Mar  1 12:35:56.789: IP SLAs Monitor: Sending ICMP echo request to 192.168.1.1
*Mar  1 12:35:56.790: IP SLAs Monitor: Received ICMP echo reply from 192.168.1.1
*Mar  1 12:35:56.790: IP SLAs Monitor: RTT = 14 ms
*Mar  1 12:35:56.790: IP SLAs Monitor: Operation 10 completed successfully

What does this output indicate?

Accepted Answer

The IP SLA monitor operation is successfully sending and receiving ICMP echo probes.. This debug output shows the IP SLA monitor trace for operation 10. Each cycle shows a successful ICMP echo request/reply with RTT values, indicating the probe is working correctly.

Answer

The IP SLA monitor operation is failing because the RTT values are increasing.

Answer

The IP SLA monitor operation is not configured because no configuration is shown.

Answer

The IP SLA monitor operation is timing out because no reply is received.

Question 16

Which IP SLA operation type is used to monitor the availability of a TCP-based service by attempting a three-way handshake?

Accepted Answer

TCP Connect. The TCP Connect operation (type 5) attempts to establish a TCP connection to a specified port. Success indicates the service is reachable; failure indicates a problem.

Answer

UDP Jitter

Answer

ICMP Echo

Answer

HTTP

Question 17

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

R1# show bgp ipv4 unicast 192.168.4.0/24
BGP routing table entry for 192.168.4.0/24, version 2
Paths: (1 available, best #1, table default)
  Advertised to update-groups:
     1
  Refresh Epoch 1
  Local
    10.1.1.2 from 10.1.1.2 (2.2.2.2)
      Origin IGP, metric 0, localpref 100, valid, external, best
      rx pathid: 0, tx pathid: 0x0

What does this output indicate?

Accepted Answer

The route is an external BGP route with administrative distance 20.. The output shows BGP route details including the path attributes. The administrative distance for BGP external routes is 20 by default, but this is not shown here. The output indicates the route is learned via eBGP and is the best path.

Answer

The route is an internal BGP route with administrative distance 200.

Answer

The route has a local preference of 200, making it preferred.

Answer

The route is not the best path because it is external.

Question 18

What is the default administrative distance for a route learned via the Border Gateway Protocol (BGP) from an external peer (eBGP)?

Accepted Answer

20. eBGP routes have a default administrative distance of 20, which is lower than iBGP's default AD of 200.

Answer

200

Answer

170

Answer

1

Question 19

Drag and drop the steps to troubleshoot Administrative Distance adjacency or connectivity failures into the correct order, from first to last.

Accepted Answer

Verify physical connectivity and interface status. First, verify the physical connectivity and layer 1/2 status, then check the routing protocol neighbor adjacency, next examine the AD values of the routes learned from the neighbor, then review any route filtering or redistribution policies, and finally test end-to-end connectivity to confirm the fix.

Question 20

A network engineer is troubleshooting an OSPF network where an ABR (R1) is configured with the 'area 1 range 10.0.0.0 255.255.0.0' command to summarize routes from area 1 into area 0. After the configuration, routers in area 0 lose connectivity to the 10.0.1.0/24 subnet, although the summary route 10.0.0.0/16 is present in their routing tables. What is the most likely cause?

Accepted Answer

The summary route is installed, but the next-hop IP address for the summary route is not reachable from routers in area 0, causing traffic to be dropped.. The issue is that the summary route may be installed, but the more specific routes are suppressed. If the summary route points to a next hop that is not reachable or has a higher metric, traffic may be black-holed.

Answer

The summary route 10.0.0.0/16 is being advertised with a metric of 0, causing routers to prefer a default route instead.

Answer

The ABR is not generating the summary route because the component routes are not all in the same area.

Answer

The 10.0.1.0/24 subnet is not included in the summary range because the range command uses a network mask that does not match the subnet's network address.