300-410 Practice Test 36 — 15 Questions

Question 1

In a DMVPN Phase 2 network with EIGRP, R1 (hub) and R2 (spoke) are configured with EIGRP stub leaking. R2 is a stub router with 'eigrp stub connected summary'. R3 (another spoke) is not a stub. R2's loopback 10.0.0.1/32 is not reachable from R3, even though R2 advertises it via EIGRP. What is the root cause?

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

Accepted Answer

NHRP is not configured on R2, preventing route advertisement.. In DMVPN Phase 2, EIGRP stub leaking allows the hub to advertise spoke routes to other spokes, but the next-hop remains the spoke's tunnel IP. For R3 to install the route to 10.0.0.1/32, it must have an NHRP mapping to reach R2's tunnel IP. Without NHRP configured on R2, R3 cannot resolve the next-hop, making the route unreachable. The EIGRP stub configuration is correct, but NHRP is missing.

Answer

R2 is configured with 'eigrp stub receive-only', which prevents it from advertising any routes, including connected ones.

Answer

R3 has a distribute-list filtering the prefix 10.0.0.1/32 from EIGRP updates.

Answer

R2's loopback is not in the same EIGRP autonomous system as the tunnel.

Question 2

A large enterprise network is experiencing intermittent reachability from a specific subnet (10.1.1.0/24) to a critical server (192.168.10.10). Router R1 has PBR configured to forward traffic from 10.1.1.0/24 to next-hop 10.2.2.2, but traffic is also being load-balanced via the routing table to 10.3.3.3. Router R2 shows: 'show ip route 192.168.10.10' returns a route via 10.4.4.4, but 'show ip policy' on R1 shows the route-map is applied. What is the root cause?

Accepted Answer

The route-map is missing the 'set ip next-hop verify-availability' command, causing PBR to forward traffic to an unreachable next-hop.. PBR uses a route-map to match traffic and set next-hop. If the route-map does not have a 'set ip next-hop verify-availability' command, PBR will forward traffic to the next-hop even if it is not reachable. In this scenario, the next-hop 10.2.2.2 is not reachable, but PBR still forwards traffic to it, causing intermittent reachability. The routing table load-balancing to 10.3.3.3 works, but PBR overrides it for matched traffic.

Answer

The ACL in the route-map is incorrectly matching traffic from 10.1.1.0/24, causing PBR to be applied to the wrong traffic.

Answer

The routing table on R1 has a higher administrative distance for the route to 192.168.10.10 via 10.3.3.3, causing PBR to be ignored.

Answer

The next-hop 10.2.2.2 is reachable but the path is congested, causing intermittent packet drops.

Question 3

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

Accepted Answer

Check flow monitor status on interface. Verification starts with checking that the flow monitor is active on the interface, then confirming flow records are being generated, then checking exporter statistics for sent packets, then validating the collector receives the data, and finally comparing flow counts to interface counters for accuracy.

Question 4

Examine the following EIGRP configuration on Router R3:

interface GigabitEthernet0/1
 ip bandwidth-percent eigrp 100 50

What is the effect of this command?

Accepted Answer

EIGRP will limit its control traffic to 50% of the interface bandwidth.. The `ip bandwidth-percent eigrp` command controls the percentage of the interface bandwidth that EIGRP can use for its control traffic (hello packets, updates, queries, and replies). By setting it to 50%, EIGRP will limit its control traffic to 50% of the configured interface bandwidth, preventing it from overwhelming the link. This does not affect data traffic or metric calculation.

Answer

EIGRP will use only 50% of the interface bandwidth for data traffic.

Answer

EIGRP will adjust the metric calculation to use 50% of the bandwidth.

Answer

EIGRP will form neighbor adjacencies only when bandwidth usage is below 50%.

Question 5

A network engineer is troubleshooting a router that is not executing an EEM applet that is supposed to run when a specific interface goes down. The applet is configured with event syslog pattern 'LINK-3-UPDOWN' and matches the interface with a regex. The engineer checks the syslog and sees the message 'LINK-3-UPDOWN: GigabitEthernet0/1, changed state to down' but the applet does not run. What is the most likely cause?

Accepted Answer

The regex pattern in the applet does not match the syslog message.. The EEM applet may have a regex that does not match the actual syslog message format. The engineer should verify the regex pattern using 'show event manager policy' or test the pattern.

Answer

The EEM applet is disabled.

Answer

The syslog message is not being sent to the EEM server due to logging level restrictions.

Answer

The interface is not being monitored because it is a subinterface.

Question 6

An OSPFv3 network has multiple areas. Area 0 includes R1 and R2. Area 1 includes R2 and R3. R2 is an ABR. R1 has an IPv6 ACL applied inbound on the interface to R2 that permits only OSPFv3 and denies all other traffic. R3 advertises a prefix 2001:db8:3::/48 into Area 1. R1's routing table shows the prefix but with a next-hop of R2. R1's uRPF is configured in strict mode on the interface to R2. Traffic from R1 to 2001:db8:3::1 is dropped. R1 shows 'show ipv6 cef 2001:db8:3::/48' points to R2's link-local address. What is the root cause?

Accepted Answer

The source address of the traffic from R1 is not in the FIB as reachable via the interface facing R2, causing uRPF strict mode to drop the packet.. The root cause is that R1's uRPF strict mode checks the source address of incoming packets against the FIB to ensure the best reverse path to that source is via the same interface. Traffic from R1 to 2001:db8:3::1 uses a source address from R1's own subnet, but the FIB entry for that source address points out a different interface (or is not present), causing uRPF to drop the packet. The ACL permits OSPFv3 but blocks all other traffic, which prevents the return traffic from R3 from reaching R1, but the immediate failure is due to uRPF dropping the forward packet.

Answer

The ACL on R1 blocks the return traffic from the destination, causing asymmetric routing.

Answer

R2's link-local address is not reachable due to OSPFv3 network type mismatch.

Answer

The prefix 2001:db8:3::/48 is not in the OSPFv3 database on R1 due to area filtering.

Question 7

A network engineer runs the following command to verify IPv6 uRPF drops:

R1# show ipv6 traffic | include verify
  0 verify source drops, 0 verify source suppressed drops

What does this output indicate?

Accepted Answer

No IPv6 packets have been dropped by uRPF checks.. The output shows '0 verify source drops' and '0 verify source suppressed drops', which are the counters for IPv6 unicast Reverse Path Forwarding (uRPF) drops. Since both counters are zero, no IPv6 packets have been dropped by uRPF checks. This does not necessarily mean uRPF is not configured; it simply indicates that no packets have failed the uRPF verification process.

Answer

uRPF is not configured on any interface.

Answer

uRPF is dropping all packets.

Answer

The router is not processing IPv6 traffic.

Question 8

A network engineer runs the following command to troubleshoot a Policy-Based Routing (PBR) issue:

R1# debug ip policy
Policy routing debugging is on
R1#
*Mar  1 00:05:23.123: IP: s=192.168.1.10 (FastEthernet0/0), d=10.1.1.100, len 100, policy match
*Mar  1 00:05:23.123: IP: s=192.168.1.10 (FastEthernet0/0), d=10.1.1.100, len 100, policy rejected

What does this output indicate?

Accepted Answer

The packet matched the route-map but was not forwarded due to a failed next-hop check.. The debug output shows a packet from 192.168.1.10 to 10.1.1.100 that matches the policy but is then rejected. This typically occurs when the set clause specifies a next-hop that is unreachable or when verify-availability fails.

Answer

The packet was successfully policy-routed to the next-hop.

Answer

The route-map does not have a match clause for this packet.

Answer

The packet was dropped due to an ACL deny.

Question 9

In MPLS LDP, what is the default label retention mode on Cisco IOS-XE routers?

Accepted Answer

Liberal Label Retention mode. The default label retention mode is Liberal, meaning that a router retains all label bindings received from neighbors, even if the neighbor is not the next hop for the FEC.

Answer

Conservative Label Retention mode

Answer

Ordered Label Retention mode

Answer

Independent Label Retention mode

Question 10

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 11

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 12

Router R1 and R2 are running EIGRP. R1 has a route to 172.16.0.0/16 with AD 90. R2 redistributes a static route for 172.16.0.0/16 into EIGRP with a route-map that sets the administrative distance to 85. R1 learns the redistributed route with AD 85 and installs it, overriding the original internal route. However, R1's 'show ip route 172.16.0.0' shows the route via R2 with AD 85, but pings to 172.16.1.1 fail. What is the most likely cause?

Accepted Answer

The redistributed route is a summary route that does not contain the specific subnet 172.16.1.0/24, causing packets to be dropped.. Setting AD to 85 makes the redistributed route preferred over the internal route (AD 90). However, the redistributed route might have a less specific prefix (e.g., 172.16.0.0/16) while the internal route might have a more specific prefix (e.g., 172.16.1.0/24) that is now hidden. The ping fails because the redistributed route is a summary that does not have a valid next hop for the specific subnet. The correct answer is that the redistributed route is a summary that does not include the specific subnet, causing blackholing.

Answer

The route-map set distance 85 is ignored because EIGRP internal routes always have AD 90.

Answer

R1's EIGRP process has a distribute-list blocking the redistributed route.

Answer

The redistributed route has a higher metric than the internal route, but AD overrides metric.

Question 13

A large enterprise network is experiencing intermittent reachability to a specific /24 subnet (192.168.10.0/24) from remote sites. Router R1 has the following relevant configuration:
interface GigabitEthernet0/0
 ip address 10.0.1.1 255.255.255.0
!
router eigrp 100
 network 10.0.0.0
 network 192.168.0.0
!
interface GigabitEthernet0/1
 ip address 192.168.1.1 255.255.255.0
 ip summary-address eigrp 100 192.168.0.0 255.255.252.0
!
Router R2 shows:
R2# show ip route 192.168.10.0
Routing entry for 192.168.0.0/22, supernet
  Known via "eigrp 100", distance 90, metric 30720, type internal
  Last update from 10.0.1.1 on GigabitEthernet0/0, 00:00:15 ago
  * 10.0.1.1, via GigabitEthernet0/0, 00:00:15 ago
What is the root cause?

Accepted Answer

The summary route 192.168.0.0/22 does not include 192.168.10.0/24, so the specific route is not advertised and is missing from R2's routing table.. The summary route 192.168.0.0/22 is being advertised by R1, but it blocks the more specific /24 route 192.168.10.0/24 if that subnet is not within the summary range (192.168.0.0/22 covers 192.168.0.0 to 192.168.3.255). Since 192.168.10.0/24 is outside this range, it is not summarized and is not advertised separately, causing reachability failure. The correct fix is to adjust the summary prefix to include the missing subnet, or to not summarize.

Answer

EIGRP has a metric mismatch between the summary and the specific route, causing the specific route to be suppressed.

Answer

The network command for 192.168.0.0 is missing, causing EIGRP to not advertise any 192.168.x.x routes.

Answer

R2 has a static route for 192.168.10.0/24 that is overriding the EIGRP route.

Question 14

What is the default behavior of an IPv4 access control list (ACL) when no explicit permit or deny statement matches a packet?

Accepted Answer

The packet is denied.. By default, IPv4 ACLs have an implicit deny any statement at the end. If a packet does not match any explicit permit or deny entry, the implicit deny any is applied, causing the packet to be dropped. This behavior is fundamental to ACL security, ensuring that only explicitly permitted traffic is allowed.

Answer

The packet is permitted.

Answer

The packet is logged and then permitted.

Answer

The ACL is ignored and the packet is forwarded.

Question 15

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