300-410 Mock Exam 72 — 25 Questions

Question 1

A network engineer is troubleshooting a redistribution issue between OSPF and EIGRP. Router R3 is redistributing OSPF routes into EIGRP, but some OSPF external routes are not appearing in the EIGRP topology table. The engineer checks the redistribute command under EIGRP and sees a route-map named RM-OSPF that uses a prefix-list to match specific prefixes. The missing routes are permitted by the prefix-list. What is the most likely cause?

Accepted Answer

The route-map is missing a 'set metric' command; EIGRP requires a metric for redistributed routes.. The route-map may have a 'set metric' command that is misconfigured, or the route-map may be missing the 'set metric' command entirely, causing EIGRP to reject the route because it requires a metric for redistributed routes. Alternatively, the route-map might have a 'match route-type' that excludes external type-2 routes.

Answer

The prefix-list is using the wrong sequence number and is being overridden by a later deny statement.

Answer

The OSPF routes are type-5 LSAs, which cannot be redistributed into EIGRP.

Answer

The route-map is applied to the OSPF process instead of the EIGRP process.

Question 2

A network engineer runs the following command on Router R1:

R1# show ip sla statistics 4

Round Trip Time (RTT) for Index 4
   Latest RTT: 300 ms
   Latest RTT (milliseconds): 300
   Latest RTT (microseconds): 300000
   Number of successes: 45
   Number of failures: 55
   Operation time to live: Forever
   Output: Over threshold

R1# show track 2
Track 2
  IP SLA 4 reachability
  Reachability is Down
    5 changes, last change 00:00:05
  Latest operation return code: Over threshold
  Latest RTT (milliseconds): 300
  Tracked by:
    ip route 0.0.0.0 0.0.0.0 192.168.2.1 track 2

Based on this output, which statement is correct?

Accepted Answer

The IP SLA threshold has been exceeded, causing the track to go down and the static route to be removed.. The track shows 'Down' because the IP SLA return code is 'Over threshold'. This means the threshold was exceeded, and the track has brought down the static route. The failures (55) are high, but the key is that the track is down due to the threshold violation.

Answer

The IP SLA operation is failing because the target is unreachable.

Answer

The tracked static route is active because the IP SLA has successes.

Answer

The IP SLA operation has a 55% failure rate, but the track is still up.

Question 3

Drag and drop the steps to troubleshoot Route Maps and Route Filtering adjacency or connectivity failures into the correct order, from first to last.

Accepted Answer

Verify BGP neighbor state with show ip bgp summary. Start by verifying BGP neighbor state with show ip bgp summary. Next, examine the route-map configuration for syntax errors using show route-map. Then, check if the route-map is applied correctly to the neighbor with show running-config. After that, use debug ip bgp updates to see if prefixes are being filtered. Finally, adjust the route-map sequence or match criteria to resolve the issue.

Question 4

An engineer configures a DMVPN Phase 2 network. Spoke routers are configured with a route map that sets the next-hop to the tunnel interface for routes learned from the hub. This is intended to allow spoke-to-spoke direct communication. However, spoke-to-spoke traffic still goes through the hub. Which is the most likely explanation?

Accepted Answer

The route map is applied on the spoke router inbound from the hub, but it should be applied on the hub router outbound to the spokes.. In DMVPN Phase 2, spoke-to-spoke direct communication requires that the spoke routers have a route with the next-hop set to the tunnel interface of the remote spoke. However, if the route map is applied inbound on the spoke from the hub, it sets the next-hop to the hub's tunnel interface, not the remote spoke. The correct approach is to use a route map on the hub that sets the next-hop to the spoke's tunnel IP when advertising routes, or to use the 'next-hop-self' command incorrectly. The edge case is that the route map is applied on the spoke, not the hub.

Answer

The route map uses a prefix-list that does not match the spoke's subnet.

Answer

The spoke routers have NHRP authentication mismatch, preventing direct communication.

Answer

The tunnel mode is mGRE on the spokes, which does not support spoke-to-spoke.

Question 5

A network engineer runs the following command on Router R1:

R1# show ip bgp neighbors 192.168.1.2 advertised-routes
BGP table version is 14, local router ID is 10.1.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
              r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
x best-external, a additional-path, c RIB-compressed,
Origin codes: i - IGP, e - EGP, ? - incomplete

Network          Next Hop            Metric LocPrf Weight Path
*> 10.10.10.0/24    192.168.1.2              0             0 65001 i
*> 10.20.20.0/24    192.168.1.2              0             0 65001 i

Total number of prefixes 2

Based on this output, what is a likely issue?

Accepted Answer

The neighbor 192.168.1.2 is not receiving all routes because a route-map is filtering them.. The output shows only two prefixes advertised to the neighbor, but the network likely has more routes. The route-map applied to the neighbor may be filtering routes. The correct answer identifies that a route-map is likely filtering out other prefixes.

Answer

The BGP session is down because there are no prefixes advertised.

Answer

The router is not receiving updates from its peers.

Answer

The prefix-list is misconfigured and blocking all routes.

Question 6

An OSPF network is experiencing routing loops between two routers. R1 has the following configuration: interface GigabitEthernet0/0 ip address 10.1.1.1 255.255.255.0 ip ospf network point-to-point. R2 has: interface GigabitEthernet0/0 ip address 10.1.1.2 255.255.255.0 ip ospf network broadcast. Both routers are in area 0. R1 shows: 'show ip ospf neighbor' lists R2 as FULL/DR, but R2 shows R1 as FULL/DROTHER. Traffic between two subnets behind each router is looping. What is the root cause?

Accepted Answer

The OSPF network type mismatch causes both routers to become DR/BDR, leading to incorrect LSA generation and routing loops.. OSPF network type mismatch on a multi-access link can cause adjacency issues. R1 is configured as point-to-point, which does not participate in DR/BDR election and expects a point-to-point link. R2 is configured as broadcast, which expects a DR/BDR election. This mismatch can cause both routers to form an adjacency (since OSPF still works), but they have different views of the network. R1 thinks the link is point-to-point and does not expect a DR, so it may advertise the link as a stub network or with different metrics. R2 thinks it is the DR (since R1 is not participating in election), and it advertises the link as a transit network. This inconsistency can cause routing loops because R1 may advertise a route via R2, and R2 may advertise the same route via R1, creating a loop. The correct fix is to match the network type on both ends.

Answer

The IP addresses are on the same subnet, but the OSPF cost is set differently, causing unequal cost load balancing.

Answer

The OSPF hello and dead intervals are mismatched due to the network type, causing the adjacency to flap.

Answer

The OSPF area is misconfigured; one router is in a different area.

Question 7

A network engineer runs the following command to verify BGP route filtering:

R1# show bgp ipv4 unicast 192.168.1.0/24
BGP routing table entry for 192.168.1.0/24, version 2
Paths: (1 available, best #1, table default)
  Advertised to update-groups:
     1
  Refresh Epoch 1
  Local, (received & used)
    10.1.1.2 (metric 20) from 10.1.1.2 (2.2.2.2)
      Origin IGP, metric 0, localpref 100, valid, internal, best
      rx pathid: 0, tx pathid: 0x0
      Community: no-export

What does the 'Community: no-export' indicate?

Accepted Answer

The route will not be advertised to any eBGP peers.. The community 'no-export' indicates that this route should not be advertised to any eBGP peers. This is a well-known community that controls route propagation.

Answer

The route will not be advertised to any iBGP peers.

Answer

The route is filtered by an inbound route-map.

Answer

The route is not installed in the routing table.

Question 8

An engineer configures unicast Reverse Path Forwarding (uRPF) in strict mode on an interface connected to a service provider. The router has a default route pointing to the ISP. Traffic from the ISP is being dropped by uRPF. Which is the most likely explanation?

Accepted Answer

Strict mode uRPF does not use the default route for verification unless the 'allow-default' option is enabled.. Strict mode uRPF checks that the source IP of incoming packets has a matching route in the routing table that points back to the same interface. If the router has a default route, it may not match the specific source IP, causing drops. However, the edge case is that the default route is not considered by strict mode unless the 'allow-default' option is configured. Without 'allow-default', strict mode requires a specific route back to the interface.

Answer

The interface is configured with the wrong IP address, causing uRPF to fail.

Answer

uRPF should be configured in loose mode to work with default routes.

Answer

The router has multiple default routes, causing uRPF to fail.

Question 9

A network engineer runs the following command on Router R1:

R1# show ip policy
Interface   Route-map
FastEthernet0/0  PBR_MAP

R1# show route-map PBR_MAP
route-map PBR_MAP, permit, sequence 10
  Match clauses:
    ip address prefix-list MATCH_HTTP
  Set clauses:
    ip next-hop 10.10.10.2
  Policy routing matches: 0 packets, 0 bytes

Based on this output, what is the most likely problem?

Accepted Answer

The prefix-list MATCH_HTTP may not be matching any traffic, causing no policy routing.. The route-map PBR_MAP is applied to FastEthernet0/0 for policy routing, but the match counter shows 0 packets matched. This indicates that either the prefix-list MATCH_HTTP is not matching any traffic, or no traffic is hitting the interface. The correct answer is that the prefix-list may be misconfigured or not matching desired traffic.

Answer

The route-map is not being applied to any interface.

Answer

The next-hop 10.10.10.2 is unreachable.

Answer

The route-map is configured with the wrong sequence number.

Question 10

Examine the following configuration on R6:

!--- R6 configuration
route-map FILTER deny 10
 match tag 50
!
route-map FILTER permit 20
!
router eigrp 200
 distribute-list route-map FILTER in
!

What is the effect of this configuration?

Accepted Answer

All routes with tag 50 are denied; all other routes are permitted.. The distribute-list route-map FILTER in is applied to EIGRP updates received on all interfaces (since no interface is specified). Sequence 10 denies any route with tag 50. Sequence 20 permits all other routes. Therefore, routes with tag 50 are filtered out (not installed in the routing table), while all other routes are accepted.

Answer

Routes with tag 50 are permitted; all other routes are denied.

Answer

The distribute-list is applied only to the first interface; routes with tag 50 are filtered on that interface.

Answer

The configuration is invalid because route-maps cannot be used with distribute-list in EIGRP.

Question 11

A network engineer runs the following command on Router R1:

R1# show ip eigrp topology 10.10.10.0/24
IP-EIGRP (AS 100): Topology entry for 10.10.10.0/24
  State is Passive, Query origin flag is 1, 1 Successor(s), FD is 131072
  Routing Descriptor Blocks:
  10.1.1.2 (FastEthernet0/0), from 10.1.1.2, Send flag is 0x0
      Composite metric is (131072/128256), Route is Internal
      Vector metric:
        Minimum bandwidth is 10000 Kbit
        Total delay is 100 microseconds
        Reliability is 255/255
        Load is 1/255
        Minimum MTU is 1500
        Hop count is 1

R1# show ip route 10.10.10.0
Routing entry for 10.10.10.0/24
  Known via "eigrp 100", distance 90, metric 131072, type internal
  Last update from 10.1.1.2 on FastEthernet0/0, 00:00:12 ago
  Routing Descriptor Blocks:
  * 10.1.1.2, from 10.1.1.2, 00:00:12 ago, via FastEthernet0/0
      Route metric is 131072, traffic share count is 1

R1# show ip eigrp interfaces
Interface         Peers    Xmit Queue   Mean   Pacing Time   Multicast    Pending
                  Un/Reliable  SRTT   Un/Reliable   Flow Timer   Routes
Fa0/0               1       0/0       10       0/10          50           0
Fa0/1               0       0/0        0       0/10          50           0

Based on this output, what is a likely issue?

Accepted Answer

EIGRP neighbor on FastEthernet0/1 is not forming due to a route-map filtering updates.. The route is in the topology table and routing table, but the interface FastEthernet0/1 has 0 peers. This suggests that a route-map filtering EIGRP updates on FastEthernet0/1 may be preventing neighbor formation or route advertisement. The correct answer is that a route-map may be filtering EIGRP updates on FastEthernet0/1.

Answer

The route 10.10.10.0/24 is not in the routing table.

Answer

The EIGRP process is not running.

Answer

The metric is too high for the route to be installed.

Question 12

A network engineer runs the following command on Router R1:

R1# show ip bgp neighbors 192.168.1.2
BGP neighbor is 192.168.1.2,  remote AS 65001, external link
  BGP version 4, remote router ID 10.2.2.2
  BGP state = Established, up for 00:15:00
  Last read 00:00:05, hold time is 180, keepalive interval is 60 seconds
  Neighbor sessions:
    1 active, is multisession capable
  Neighbor capabilities:
    Route refresh: advertised and received(new)
    Four-octets ASN: advertised and received
    Address family IPv4 Unicast: advertised and received
    Enhanced Refresh: advertised
  Message statistics:
    InQ depth is 0
    OutQ depth is 0
                         Sent       Rcvd
    Opens:                  1          1
    Notifications:          0          0
    Updates:               10          5
    Keepalives:            15         15
    Route Refresh:          0          0
    Total:                 26         21
  Default minimum time between advertisement runs is 30 seconds

For address family: IPv4 Unicast
  Session: 192.168.1.2
  BGP table version 14, neighbor version 14/0
  Output queue size : 0
  Index 1, Advertise bit 0
  1 update-group member
  Incoming update prefix filter list: FILTER_IN
  Outgoing update prefix filter list: FILTER_OUT
                                   Sent       Rcvd
  Prefixes:                           2          2
  Updates:                           10          5

Based on this output, what is the effect of the prefix lists?

Accepted Answer

The prefix lists FILTER_IN and FILTER_OUT are allowing only 2 prefixes in each direction.. The output shows that incoming and outgoing prefix filters (FILTER_IN and FILTER_OUT) are applied. The prefixes sent and received are both 2, indicating that the filters are allowing exactly 2 prefixes in each direction. The correct answer is that the prefix lists are filtering routes to only 2 prefixes.

Answer

The prefix lists are blocking all prefixes.

Answer

The prefix lists are not applied because the session is established.

Answer

The prefix lists are misconfigured and causing route flapping.

Question 13

An engineer configures a route map to filter BGP routes based on AS-path using a regex. The route map is applied inbound to an eBGP neighbor. The engineer notices that routes with an AS-path containing the neighbor's AS are still being accepted. Which is the most likely explanation?

Accepted Answer

The AS-path is prepended with the local AS before the inbound route map is applied, so the regex does not match the original AS-path.. When an eBGP route is received, the router prepends its own AS to the AS-path before the route map is applied. Therefore, if the route map is trying to match the neighbor's AS in the AS-path, it will fail because the neighbor's AS is now the first AS in the path. The edge case is that the AS-path is modified before the route map is processed.

Answer

The route map is applied outbound instead of inbound.

Answer

The regex is incorrect; it should use _AS_ to match the AS number.

Answer

The neighbor is configured with 'send-community' which overrides the route map.

Question 14

A network engineer runs the following command on Router R1:

R1# show ip route vrf CUSTOMER_A

Routing Table: CUSTOMER_A
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
       a - application route
       + - replicated route, % - next hop override

Gateway of last resort is not set

10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
B       10.10.10.0/24 [200/0] via 192.168.1.2, 00:10:00
B       10.20.20.0/24 [200/0] via 192.168.1.2, 00:10:00

R1# show ip bgp vpnv4 vrf CUSTOMER_A
BGP table version is 6, local router ID is 10.1.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
              r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
x best-external, a additional-path, c RIB-compressed,
Origin codes: i - IGP, e - EGP, ? - incomplete

Network          Next Hop            Metric LocPrf Weight Path
Route Distinguisher: 100:1 (default for vrf CUSTOMER_A)
*> 10.10.10.0/24    192.168.1.2              0             0 65001 i
*> 10.20.20.0/24    192.168.1.2              0             0 65001 i
*> 10.30.30.0/24    192.168.1.2              0             0 65001 i

Based on this output, what is the likely issue?

Accepted Answer

A route-map is filtering the route 10.30.30.0/24 from the VRF routing table.. The VRF routing table shows only two routes, but the BGP table shows three routes for the VRF. This indicates that a route-map is filtering one of the routes from being installed in the routing table. The correct answer is that a route-map is filtering the route 10.30.30.0/24.

Answer

The VRF is not properly configured.

Answer

The BGP session is down.

Answer

The route distinguisher is misconfigured.

Question 15

Examine the following partial configuration on R1:

!--- R1 configuration
route-map RMAP permit 10
 match ip address prefix-list PL-1
 set metric 100
!
route-map RMAP permit 20
 set metric 200
!
router eigrp 100
 network 10.0.0.0
 redistribute ospf 1 metric 1000 100 255 1 1500 route-map RMAP
!

What is the effect of this configuration?

Accepted Answer

Routes matching prefix-list PL-1 are redistributed with metric 100; all other OSPF routes are redistributed with metric 200.. The route-map RMAP has two permit sequences. The first matches prefix-list PL-1 and sets metric to 100. The second is a catch-all permit with no match, setting metric to 200. All redistributed OSPF routes will match either sequence and have their metric set accordingly. If a route matches the first sequence, its metric is set to 100; otherwise, it matches the second and gets metric 200. There is no deny sequence, so no routes are filtered.

Answer

Only routes matching prefix-list PL-1 are redistributed into EIGRP with metric 100; all other OSPF routes are denied.

Answer

The route-map is missing a deny statement; without it, all routes are permitted with default metric.

Answer

The route-map is applied to redistribution, but the metric values are ignored because redistribute command also specifies metric.

Question 16

Which TWO statements about the 'match ip address' command within a route-map are true? (Choose TWO.)

Accepted Answer

It can reference a standard access-list, extended access-list, or prefix-list.. The 'match ip address' command can reference either a standard or extended access-list, or a prefix-list. It matches the destination network of the route. It cannot match source address (that would be 'match ip next-hop' or 'match ip route-source'). The command can be used in both permit and deny sequences. A single route-map sequence can have multiple match commands, but they are logically ANDed only if under the same match statement type.

Answer

It matches the source IP address of the route.

Answer

It can only be used in a route-map sequence with a 'permit' clause.

Answer

The command 'match ip address prefix-list' is not valid.

Question 17

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 18

A network engineer runs the following command on Router R1:

R1# show ip sla statistics 5

Round Trip Time (RTT) for Index 5
   Latest RTT: 50 ms
   Latest RTT (milliseconds): 50
   Latest RTT (microseconds): 50000
   Number of successes: 100
   Number of failures: 0
   Operation time to live: Forever
   Output: OK

R1# show track 3
Track 3
  IP SLA 5 reachability
  Reachability is Up
    1 change, last change 00:10:00
  Latest operation return code: OK
  Latest RTT (milliseconds): 50
  Tracked by:
    ip route 0.0.0.0 0.0.0.0 192.168.3.1 track 3

R1# show ip route 0.0.0.0 0.0.0.0
Routing entry for 0.0.0.0/0, supernet
  Known via "static", distance 1, metric 0, candidate default path
  Last update from 192.168.3.1 on GigabitEthernet0/0
  Routing Descriptor Blocks:
  * 192.168.3.1, via GigabitEthernet0/0
      Route metric is 0, traffic share count is 1

Based on this output, which statement is correct?

Accepted Answer

The static route is active and reachable via 192.168.3.1.. The track is up, and the static route is present in the routing table. The IP SLA has 100% success. This indicates everything is working correctly.

Answer

The static route is not installed because the track is up.

Answer

The IP SLA operation is failing, causing the track to go down.

Answer

The IP SLA operation has a threshold violation.

Question 19

Consider the following configuration on router R2:

!--- R2 configuration
ip prefix-list FILTER seq 5 deny 10.1.0.0/16 le 24
ip prefix-list FILTER seq 10 permit 0.0.0.0/0 le 32
!
route-map BGP-IN permit 10
 match ip address prefix-list FILTER
!
router bgp 65000
 neighbor 192.168.1.1 route-map BGP-IN in
!

What is the effect of this configuration?

Accepted Answer

Routes within 10.1.0.0/16 with mask length 24 or shorter are denied; all other routes are permitted.. The prefix-list FILTER denies any prefix within 10.1.0.0/16 with a mask length less than or equal to 24 (i.e., 10.1.0.0/16 through 10.1.255.0/24). The permit statement allows all other prefixes. The route-map BGP-IN calls this prefix-list; since there is only one permit sequence, routes that match the deny statement in the prefix-list are implicitly denied by the route-map. Therefore, routes like 10.1.0.0/16, 10.1.1.0/24, etc., are filtered out.

Answer

All routes from neighbor 192.168.1.1 are accepted; the prefix-list is not applied correctly because the route-map only has a permit sequence.

Answer

Only routes with mask length exactly 24 are denied; all other routes are permitted.

Answer

The configuration is incomplete; a route-map must have a deny statement to filter routes.

Question 20

What is the default maximum hop count for RIP routes in Cisco IOS?

Accepted Answer

15. RIP uses a hop count metric with a maximum of 15 hops; 16 indicates an unreachable route. This is a fundamental loop prevention mechanism.

Answer

16

Answer

255

Answer

10