300-410 Mock Exam 75 — 25 Questions

Question 1

A network engineer runs the following command on Router R4:

R4# show ip route 10.10.10.0
Routing entry for 10.10.10.0/24
  Known via "connected", distance 0, metric 0 (connected)
  Redistributing via eigrp 100
  Last update from 10.10.10.1 on GigabitEthernet0/0, 00:00:00 ago
  Routing Descriptor Blocks:
  * 10.10.10.1, via GigabitEthernet0/0
      Route metric is 0, traffic share count is 1

Based on this output, which statement is true?

Accepted Answer

The route is a connected route, as indicated by distance 0.. The route is directly connected, as indicated by 'known via connected' and distance 0. The administrative distance of 0 is the default for connected routes.

Answer

The route is a static route with distance 0.

Answer

The route is redistributed from EIGRP into connected.

Answer

The administrative distance of 0 indicates a floating static route.

Question 2

A network engineer is troubleshooting a multi-homed BGP setup. R1 receives the prefix 10.1.1.0/24 from two eBGP peers: R2 (AS 100) and R3 (AS 200). The engineer configures the distance bgp 20 20 20 command on R1 to make all BGP routes have the same AD. However, R1 still prefers the route from R2 over R3. What is the most likely reason?

Accepted Answer

The route from R2 has a higher local preference than the route from R3.. The distance bgp command sets AD for eBGP, iBGP, and local routes. With AD equal, the router uses other BGP path attributes, such as local preference, AS path length, or MED. The most common tie-breaker is local preference (default 100) or the oldest route.

Answer

The route from R2 has a lower MED than the route from R3.

Answer

The route from R2 is the oldest BGP route.

Answer

The AS path for the route from R2 is shorter than that from R3.

Question 3

A network engineer runs the following command on Router R5:

R5# show ip route 192.168.100.0
Routing entry for 192.168.100.0/24
  Known via "static", distance 1, metric 0
  Redistributing via ospf 1
  Last update from 10.0.0.2 on GigabitEthernet0/1, 00:00:05 ago
  Routing Descriptor Blocks:
  * 10.0.0.2, via GigabitEthernet0/1
      Route metric is 0, traffic share count is 1

Based on this output, what is the likely issue if this route is not being preferred over an EIGRP route with distance 90?

Accepted Answer

The static route may have been configured with a higher distance as a floating static route.. The static route has a default distance of 1, which is lower than EIGRP's default distance of 90. If the static route is not preferred, it may have a higher distance if configured as a floating static route, or the EIGRP route may have a lower distance due to configuration.

Answer

The static route is not preferred because its distance is higher than EIGRP's default distance of 90.

Answer

EIGRP always has a lower administrative distance than static routes.

Answer

The static route is redistributed into OSPF, which changes its distance.

Question 4

Consider the following configuration on a router running BGP and OSPF:
```
router bgp 65000
 distance bgp 20 200 200
```
What is the effect of this command?

Accepted Answer

It sets the administrative distance for eBGP routes to 20, iBGP routes to 200, and local BGP routes to 200.. The `distance bgp` command sets AD for BGP routes: external (eBGP) to 20, internal (iBGP) to 200, and local to 200.

Answer

It sets the administrative distance for all BGP routes to 20.

Answer

It sets the administrative distance for eBGP routes to 200 and iBGP routes to 20.

Answer

It sets the administrative distance for BGP routes to 20 for routes learned from AS 65000.

Question 5

An engineer is troubleshooting a route redistribution issue between OSPF and EIGRP. R1 runs both protocols and redistributes OSPF into EIGRP. The engineer notices that OSPF routes redistributed into EIGRP have an AD of 170, but some routes from OSPF are not being redistributed. What is the most likely cause?

Accepted Answer

The OSPF routes are not in the routing table because they are overridden by a static route with AD 1.. Redistribution into EIGRP requires matching routes; by default, only routes in the routing table are redistributed. If OSPF routes are not in the routing table because they are overridden by another protocol with lower AD, they will not be redistributed.

Answer

The OSPF routes have a higher metric than the EIGRP routes.

Answer

The redistribute ospf 1 metric 10000 command is missing.

Answer

The OSPF routes are external type 2, which are not redistributed by default.

Question 6

A network engineer is troubleshooting a situation where R1 has two routes to 10.0.0.0/8: one via OSPF (AD 110) and one via RIP (AD 120). The engineer wants R1 to prefer the RIP route. After configuring the distance 80 0.0.0.0 255.255.255.255 under the RIP process, the RIP route is still not preferred. What is the most likely reason?

Accepted Answer

The OSPF process has the distance ospf external 70 command configured, lowering the AD of OSPF external routes to 70.. The distance command under RIP can set AD for specific routes. However, if the OSPF route has a lower AD than the new RIP AD, it will still be preferred. The engineer set RIP AD to 80, but OSPF AD is 110, so RIP should be preferred. If it is not, the OSPF AD may have been lowered or the distance command was applied incorrectly.

Answer

The OSPF route has an AD of 110, but the RIP route's AD was set to 80, so RIP should be preferred. The issue is that the distance command was applied to the wrong prefix.

Answer

The RIP route is not in the routing table because it is suppressed by a distribute-list.

Answer

The distance command under RIP only affects internal RIP routes, not redistributed routes.

Question 7

A network engineer configured IP SLA to track a BGP next-hop for a backup path. Router R1 has:

ip sla 2
 icmp-echo 192.168.2.2 source-ip 192.168.1.1
 frequency 5
ip sla schedule 2 life forever start-time now

track 2 ip sla 2 reachability

router bgp 65001
 bgp log-neighbor-changes
 neighbor 192.168.2.2 remote-as 65002
 neighbor 192.168.2.2 fall-over bfd
 neighbor 192.168.2.2 track 2

However, when the link to 192.168.2.2 goes down, the BGP session does not reset immediately. What is the root cause?

Accepted Answer

The BGP fall-over bfd command takes precedence over the track, and since BFD is not fully operational, the session does not reset.. The BGP fall-over bfd command overrides the track 2 behavior. BFD provides faster detection, but if BFD is not configured on the neighbor or if the BFD session is not established, the track might not take effect. The correct answer is that the track 2 is ignored because BGP fall-over bfd takes precedence, and BFD is not actually operational.

Answer

The IP SLA frequency is too low, so the track does not detect the failure quickly enough.

Answer

The source IP in the IP SLA must match the BGP update-source; otherwise, the track is ignored.

Answer

The track 2 is not applied to the BGP neighbor correctly; it should be under the address-family.

Question 8

An engineer is troubleshooting a network where R1 and R2 are running iBGP, and R1 learns the prefix 192.168.1.0/24 from R2 with an AD of 200. R1 also learns the same prefix via OSPF from R3 with AD 110. The engineer notices that R1 uses the iBGP route. What configuration change would cause this?

Accepted Answer

The engineer applied the distance 150 0.0.0.0 255.255.255.255 under the OSPF process, raising OSPF AD to 150.. iBGP routes have an AD of 200 by default, which is higher than OSPF's 110, so OSPF should be preferred. If iBGP is preferred, the AD of iBGP must have been lowered or the OSPF AD raised.

Answer

The engineer applied the distance bgp 20 200 200 command, which lowers eBGP AD but not iBGP.

Answer

The OSPF route is a type 5 LSA, which has a higher AD than type 3 LSAs.

Question 9

An enterprise uses IP SLA to track a route to a remote site via two ISPs. Router R1 has:

ip sla 3
 icmp-echo 8.8.8.8 source-ip 10.0.0.1
 frequency 10
ip sla schedule 3 life forever start-time now

track 3 ip sla 3 reachability

ip route 10.10.10.0 255.255.255.0 10.0.0.2 track 3
ip route 10.10.10.0 255.255.255.0 10.0.1.2 10

When the primary ISP fails, the backup route is used, but traffic to 10.10.10.0/24 is intermittently lost. Show output on R1:

show ip route 10.10.10.0
Routing entry for 10.10.10.0/24
  Known via "static", distance 1, metric 0
  Last update from 10.0.0.2 on GigabitEthernet0/0
  * 10.0.1.2, via GigabitEthernet0/1

What is the root cause?

Accepted Answer

The IP SLA probe to 8.8.8.8 is successful via the backup path, so the track remains up, but the primary next-hop 10.0.0.2 is down, causing traffic to be sent to a dead next-hop.. The tracked route is still present in the routing table even though the track is down. This happens because the track is only removed if the track state is 'down', but the show output shows the route is still there. The likely cause is that the track is not properly associated with the route, or the route has a higher administrative distance that is not being overridden. However, the correct answer is that the track 3 is configured with 'reachability' but the IP SLA probe may be successful due to a different path, so the track remains up, but the primary next-hop is actually unreachable, causing packet loss.

Answer

The backup route has a higher administrative distance, so it is not installed until the primary route is removed, but the track is not removing the primary route.

Answer

The IP SLA frequency is too low, causing a delay in track state change.

Answer

The track should be configured with 'ip sla 3 state' instead of 'reachability' to monitor the next-hop.

Question 10

A network engineer is troubleshooting a route selection issue between two routing protocols. R1 learns the prefix 10.0.0.0/8 via both IS-IS (AD 115) and OSPF (AD 110). The engineer wants R1 to prefer the IS-IS route. After configuring the distance 105 ip 10.0.0.0 0.255.255.255 under the IS-IS process, the IS-IS route is still not preferred. What is the most likely cause?

Accepted Answer

The IS-IS route is a level 2 route, which has a default AD of 115, but the distance command only affects level 1 routes.. The distance command under IS-IS can set AD for specific routes. With the new AD of 105, IS-IS should be preferred over OSPF (AD 110). If it is not, either the command was not applied correctly (e.g., wrong ACL) or the OSPF AD was also lowered.

Answer

The OSPF route has a lower metric than the IS-IS route.

Answer

The distance command was applied under the OSPF process instead of IS-IS.

Answer

The IS-IS route is redistributed from another protocol, so it has a higher default AD of 115.

Question 11

A network engineer runs the following command on Router R9:

R9# show ip route 192.168.50.0
Routing entry for 192.168.50.0/24
  Known via "ospf 1", distance 110, metric 20
  Redistributing via ospf 1
  Last update from 10.0.0.1 on GigabitEthernet0/0, 00:00:10 ago
  Routing Descriptor Blocks:
  * 10.0.0.1, from 10.0.0.1, 00:00:10 ago, via GigabitEthernet0/0
      Route metric is 20, traffic share count is 1

R9 also has an EIGRP route for the same prefix with distance 90 and metric 28160. Which route will be installed?

Accepted Answer

The EIGRP route will be installed because it has a lower administrative distance.. EIGRP internal routes have a default administrative distance of 90, which is lower than OSPF's default distance of 110. Therefore, the EIGRP route will be preferred and installed in the routing table.

Answer

The OSPF route will be installed because it has a lower metric.

Answer

Both routes will be installed for load balancing.

Answer

Neither route will be installed due to a conflict.

Question 12

Which of the following protocols has the lowest default administrative distance on a Cisco router?

Accepted Answer

Connected. Connected routes have an AD of 0, which is the lowest. Static routes are 1, eBGP is 20, EIGRP internal is 90.

Answer

eBGP

Answer

OSPF

Answer

EIGRP internal

Question 13

A network engineer runs the following command on Router R6:

R6# show ip route 10.0.0.0
Routing entry for 10.0.0.0/8
  Known via "eigrp 100", distance 90, metric 28160
  Redistributing via eigrp 100
  Last update from 192.168.1.1 on GigabitEthernet0/0, 00:00:10 ago
  Routing Descriptor Blocks:
  * 192.168.1.1, from 192.168.1.1, 00:00:10 ago, via GigabitEthernet0/0
      Route metric is 28160, traffic share count is 1

Additionally, an OSPF route for the same prefix is learned with distance 110. Which route will be installed in the routing table?

Accepted Answer

The EIGRP route will be installed because it has a lower administrative distance.. EIGRP internal routes have a default administrative distance of 90, which is lower than OSPF's default distance of 110. Therefore, the EIGRP route will be preferred and installed in the routing table.

Answer

The OSPF route will be installed because it has a lower metric.

Answer

Both routes will be installed for load balancing.

Answer

Neither route will be installed due to a conflict.

Question 14

A network engineer configures the following on a router:
```
router eigrp 100
 distance 150 10.0.0.0 0.255.255.255
```
What is the intended effect?

Accepted Answer

It sets the administrative distance to 150 for routes learned from any neighbor whose source IP matches the wildcard mask 0.255.255.255.. The `distance` command with an access-list qualifier sets AD for routes matching the ACL. Here, routes from the 10.0.0.0/8 range will have AD 150.

Answer

It sets the administrative distance for all EIGRP routes to 150.

Answer

It sets the administrative distance to 150 for all routes in the routing table with destination 10.0.0.0/8.

Answer

It sets the administrative distance to 150 for EIGRP external routes only.

Question 15

Which THREE symptoms indicate that an administrative distance misconfiguration might be causing routing issues? (Choose THREE.)

Accepted Answer

The router prefers a route learned via a less reliable protocol over a more reliable one.. When AD is misconfigured, the router may prefer a less reliable route, causing suboptimal or intermittent connectivity. Common symptoms include incorrect route selection, flapping routes, and traffic taking unexpected paths. These are all signs that the AD values should be reviewed.

Answer

Routes are flapping in the routing table due to metric changes.

Answer

The routing table shows two routes to the same network with different AD values.

Question 16

An engineer configures IP SLA to track a route to a loopback address for BGP next-hop tracking. Router R1 has:

ip sla 4
 icmp-echo 192.168.100.1 source-ip 10.0.0.1
 frequency 5
ip sla schedule 4 life forever start-time now

track 4 ip sla 4 reachability

router bgp 65001
 neighbor 10.0.0.2 remote-as 65002
 neighbor 10.0.0.2 update-source Loopback0
 neighbor 10.0.0.2 ebgp-multihop 2
 neighbor 10.0.0.2 fall-over bfd

But the BGP session to 10.0.0.2 is flapping every 5 seconds. What is the root cause?

Accepted Answer

The IP SLA probe is sending ICMP packets that are being rate-limited by the CoPP policy, causing the BFD session to drop.. The IP SLA probe is sent to 192.168.100.1, but the BGP neighbor is 10.0.0.2. The track is not directly affecting the BGP session. However, the flapping is caused by the BFD session failing because the IP SLA might be interfering with the BFD packets, or more likely, the ebgp-multihop and BFD interaction. The correct answer is that the BFD session is using the same path as the IP SLA, and the IP SLA probe is causing the BFD session to reset due to packet loss or delay.

Answer

The ebgp-multihop 2 is not sufficient for the BFD session to establish.

Answer

The update-source Loopback0 is not reachable from 10.0.0.2.

Answer

The IP SLA schedule is set to start now, but the frequency is too high, causing the router to crash.

Question 17

A network engineer runs the following command on Router R7:

R7# show ip route 172.16.0.0
Routing entry for 172.16.0.0/16
  Known via "bgp 65000", distance 200, metric 0
  Redistributing via bgp 65000
  Last update from 10.0.0.1 00:00:20 ago
  Routing Descriptor Blocks:
  * 10.0.0.1, from 10.0.0.1, 00:00:20 ago
      Route metric is 0, traffic share count is 1

Based on this output, what type of BGP route is this?

Accepted Answer

This is an iBGP route because the distance is 200.. The administrative distance of 200 is the default for iBGP routes. eBGP routes have a default distance of 20. Therefore, this is an iBGP route.

Answer

This is an eBGP route because the distance is 200.

Answer

This is a redistributed route from OSPF into BGP.

Answer

The distance of 200 is non-default and manually configured.

Question 18

Examine this configuration:
```
router ospf 1
 distance ospf intra-area 150 inter-area 160 external 170
```
What is the effect of this command?

Accepted Answer

It sets the administrative distance for intra-area OSPF routes to 150, inter-area to 160, and external to 170.. This command sets different administrative distances for different OSPF route types: intra-area to 150, inter-area to 160, external to 170.

Answer

It sets the administrative distance for all OSPF routes to 150.

Answer

It sets the administrative distance for OSPF routes to 150, but only for routes learned from area 1.

Answer

It sets the administrative distance for OSPF external routes to 170 and leaves intra-area and inter-area at default.

Question 19

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 20

A company uses IP SLA to track a route to a remote network via a DMVPN tunnel. Router R1 (hub) has:

ip sla 5
 icmp-echo 172.16.0.1 source-ip 10.0.0.1
 frequency 10
ip sla schedule 5 life forever start-time now

track 5 ip sla 5 reachability

ip route 192.168.1.0 255.255.255.0 Tunnel0 track 5

Tunnel0 is a DMVPN tunnel to spoke R2. The tunnel is up, but the route is intermittently removed. Show output on R1:

show ip route 192.168.1.0
% Subnet not in table

show track 5
Track 5
  IP SLA 5 reachability
  Reachability is Down
  2 changes, last change 00:00:05

What is the root cause?

Accepted Answer

The source IP of the IP SLA probe is not the tunnel source, so the probe is sent out the physical interface and does not reach the destination.. The IP SLA probe is sent to 172.16.0.1, which is the tunnel IP of R2. However, the DMVPN tunnel might be using a different encapsulation (e.g., mGRE) and the probe might be sent over the physical interface instead of the tunnel, or the tunnel might be in a VRF. The correct answer is that the IP SLA probe is sourced from 10.0.0.1, which is not the tunnel source, so the probe goes out the physical interface and may not reach 172.16.0.1, causing the track to go down.

Answer

The DMVPN tunnel is down because the spoke is not reachable.

Answer

The IP SLA frequency is too low, causing the track to go down after 10 seconds of no response.

Answer

The route is removed because the track is down, but the track is down due to a routing loop in the DMVPN network.