300-410 Practice Exam 3 — 20 Questions

Question 1

A network engineer runs the following command to debug IPv6 traffic filtering:

R1# debug ipv6 packet access-list FILTER detail
IPv6 packet debugging is on for access list FILTER (detail)

*Mar 1 00:01:23.456: IPv6: source 2001:DB8:2::1 (GigabitEthernet0/0)
*Mar 1 00:01:23.456:   dest 2001:DB8:3::1 (GigabitEthernet0/1)
*Mar 1 00:01:23.456:   traffic class 0, flowlabel 0, hlim 64, next header 6 (TCP)
*Mar 1 00:01:23.456:   denied by access-list FILTER

What does this output indicate?

Accepted Answer

The packet is denied because the source address 2001:DB8:2::1 matches the deny entry in the access list.. The debug output shows an IPv6 packet from 2001:DB8:2::1 to 2001:DB8:3::1 being denied by access-list FILTER. This matches the deny statement for the 2001:DB8:2::/48 prefix.

Answer

The packet is permitted because it is a TCP packet.

Answer

The packet is denied because of uRPF check failure.

Answer

The packet is permitted because the destination is not in the access list.

Question 2

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 counters for uRPF drops. Both counters are zero, indicating no packets have been dropped due to uRPF verification.

Answer

uRPF is not configured on any interface.

Answer

uRPF is dropping all packets.

Answer

The router is not processing IPv6 traffic.

Question 3

A network engineer runs the following command to debug IPv6 uRPF:

R1# debug ipv6 verify
IPv6 verify debugging is on

*Mar 1 00:02:34.567: IPv6 verify: source 2001:DB8:4::1 on GigabitEthernet0/0
*Mar 1 00:02:34.567:   no route to source

What does this output indicate?

Accepted Answer

The packet will be dropped because uRPF cannot find a route to the source address.. The debug output shows that a packet with source address 2001:DB8:4::1 arrived on GigabitEthernet0/0, but the router has no route to that source address. With uRPF enabled, this packet will be dropped.

Answer

The packet will be forwarded because uRPF only checks the destination.

Answer

The packet will be forwarded because the source is on the same interface.

Answer

The router will add a route to the source address.

Question 4

A network engineer runs the following command to verify IPv6 access-list hits:

R1# show ipv6 access-list FILTER | include matches
    permit ipv6 2001:DB8:1::/48 any sequence 10 (10 matches)
    deny ipv6 2001:DB8:2::/48 any sequence 20 (5 matches)
    permit ipv6 any any sequence 30 (100 matches)

What does this output indicate?

Accepted Answer

5 packets from 2001:DB8:2::/48 have been denied, and 110 packets have been permitted.. The output shows the number of packets matching each entry. Sequence 10 has 10 matches, sequence 20 has 5 matches (denied), and sequence 30 has 100 matches (permitted).

Answer

All packets from 2001:DB8:2::/48 have been permitted.

Answer

The access list has been applied to an interface but not used.

Answer

The access list is invalid because of the order of entries.

Question 5

A network engineer runs the following command to verify IPv6 uRPF on an interface:

R1# show ipv6 interface GigabitEthernet0/0 | include verify|suppress
  IPv6 verify source: strict
  IPv6 verify source suppress: disabled

What does this output indicate?

Accepted Answer

Strict uRPF is enabled, and no suppression is configured, so all incoming packets are subject to strict verification.. The output shows strict uRPF is enabled and the suppress feature is disabled. Suppress allows uRPF to be bypassed for certain traffic (e.g., from known sources).

Answer

Loose uRPF is enabled with suppression.

Answer

uRPF is disabled on this interface.

Answer

Suppression is enabled, so uRPF checks are bypassed.

Question 6

Which IPv6 traffic filter can be used to match traffic based on the Flow Label field?

Accepted Answer

IPv6 access-list with the 'flow-label' option. IPv6 access-lists support matching on the flow label using the 'flow-label' keyword.

Answer

IPv6 prefix-list

Answer

IPv6 route-map with match ipv6 address

Answer

IPv6 uRPF

Question 7

A network engineer runs the following command to debug IPv6 uRPF with detailed information:

R1# debug ipv6 verify detail
IPv6 verify debugging is on (detail)

*Mar 1 00:03:45.678: IPv6 verify: source 2001:DB8:5::1 on GigabitEthernet0/0
*Mar 1 00:03:45.678:   route to source via GigabitEthernet0/1, not same as input interface

What does this output indicate?

Accepted Answer

The packet will be dropped because strict uRPF requires the return path to be through the same interface.. The debug output shows that a packet from source 2001:DB8:5::1 arrived on GigabitEthernet0/0, but the route to that source points out GigabitEthernet0/1. With strict uRPF, this packet will be dropped because the return path is not through the receiving interface.

Answer

The packet will be forwarded because a route exists.

Answer

The packet will be forwarded because uRPF is loose.

Answer

The router will change the route to use GigabitEthernet0/0.

Question 8

A network engineer runs the following command to verify IPv6 traffic filtering with logging:

R1# show logging | include FILTER
*Mar 1 00:04:56.789: %IPV6_ACL-6-ACCESSLOGDP: list FILTER denied tcp 2001:DB8:2::1(12345) -> 2001:DB8:3::1(80), 1 packet

What does this output indicate?

Accepted Answer

A TCP packet from 2001:DB8:2::1 to destination 2001:DB8:3::1 port 80 was denied by the access list.. The log message shows that a TCP packet from 2001:DB8:2::1 to 2001:DB8:3::1 was denied by the access-list FILTER. This is consistent with the deny entry for 2001:DB8:2::/48.

Answer

A TCP packet was permitted by the access list.

Answer

The access list is not applied to any interface.

Answer

The packet was dropped due to uRPF.

Question 9

What is the default administrative distance for IPv6 static routes in Cisco IOS-XE?

Accepted Answer

1. The default administrative distance for IPv6 static routes is 1, the same as for IPv4 static routes.

Answer

0

Answer

5

Answer

20

Question 10

Which statement correctly describes the behavior of IPv6 Unicast Reverse Path Forwarding (uRPF) in strict mode?

Accepted Answer

It verifies that the source address is reachable via the same interface and that the route points back to that interface.. Strict mode uRPF checks that the source address of an incoming packet is reachable via the same interface it arrived on, and that the route points back to that interface.

Answer

It verifies that the source address is in the routing table, but does not check the incoming interface.

Answer

It checks that the source address is reachable via the same interface and that the route is a connected route.

Answer

It only checks that the source address is not a multicast or link-local address.

Question 11

Drag and drop the steps to configure uRPF in strict mode on an edge router into the correct order, from first to last.

Accepted Answer

Enter global configuration mode. The correct order begins with entering global configuration mode, then configuring the interface, enabling IPv6 on the interface, applying uRPF strict mode, and finally verifying the configuration with a show command.

Question 12

What is the default hello interval for OSPFv3 on a broadcast network type in Cisco IOS-XE?

Accepted Answer

10 seconds. OSPFv3 uses the same default hello interval as OSPFv2: 10 seconds on broadcast and point-to-point networks.

Answer

30 seconds

Answer

40 seconds

Answer

5 seconds

Question 13

Which IPv6 access-list entry will deny traffic from any source to the destination prefix 2001:db8:1::/48?

Accepted Answer

deny ipv6 any 2001:db8:1::/48. The 'any' keyword matches any source, and the destination prefix is specified after the deny keyword.

Answer

deny ipv6 2001:db8:1::/48 any

Answer

deny ipv6 any host 2001:db8:1::1

Answer

deny ipv6 2001:db8:1::/48 2001:db8:1::/48

Question 14

What is the default metric for an IPv6 static route redistributed into OSPFv3?

Accepted Answer

20. The default metric for redistributed routes in OSPFv3 is 20, matching OSPFv2 behavior.

Answer

0

Answer

1

Answer

10

Question 15

Which statement about IPv6 uRPF loose mode is true?

Accepted Answer

It only verifies that the source address exists in the FIB.. Loose mode only checks that the source address is present in the routing table, regardless of the incoming interface.

Answer

It requires the source address to be reachable via the same interface.

Answer

It drops packets with link-local source addresses.

Answer

It is enabled by default on all interfaces.

Question 16

What is the default dead interval multiplier for OSPFv3?

Accepted Answer

4. The dead interval is calculated as the hello interval multiplied by the dead interval multiplier, which defaults to 4.

Answer

3

Answer

5

Answer

2

Question 17

What is the default administrative distance for OSPFv3 internal routes?

Accepted Answer

110. OSPFv3 uses the same administrative distance as OSPFv2: 110 for internal routes.

Answer

90

Answer

115

Answer

120

Question 18

Drag and drop the steps to troubleshoot IPv6 traffic filtering and uRPF adjacency or connectivity failures into the correct order, from first to last.

Accepted Answer

Check uRPF configuration on the interface. Troubleshooting starts with checking the uRPF configuration on the interface, then verifying the routing table for the source prefix, checking for ACLs that might block traffic, examining uRPF drop counters, and finally using debug ipv6 packet to capture dropped packets.

Question 19

Drag and drop the steps to verify and validate IPv6 traffic filtering and uRPF operational state into the correct order, from first to last.

Accepted Answer

Check uRPF config with show running-config. Validation begins with checking the uRPF configuration on the interface, then verifying the interface status, inspecting uRPF statistics, testing connectivity with ping, and finally confirming the routing table for expected routes.

Question 20

Which TWO statements about IPv6 unicast RPF (uRPF) behavior in Cisco IOS-XE are correct? (Choose TWO.)

Accepted Answer

Strict mode uRPF drops packets if the source address is not reachable via the incoming interface.. IPv6 uRPF verifies the source address of incoming packets against the FIB. Strict mode requires the source address to match the FIB entry for the incoming interface and the exact prefix. Loose mode only requires a matching FIB entry, ignoring the interface. The default is loose mode. The 'ipv6 verify unicast source reachable-via any' command enables loose mode, while 'ipv6 verify unicast source reachable-via rx' enables strict mode. uRPF is applied per interface and does not check the destination address. It can drop packets with legitimate source addresses if asymmetric routing is present.

Answer

The default uRPF mode on Cisco IOS-XE is strict mode.

Answer

IPv6 uRPF can be applied globally using the 'ipv6 unicast-rpf' command.

Answer

uRPF checks both source and destination addresses in the IPv6 header.