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Which command enables IPv6 routing on a Cisco router?

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Which command enables IPv6 routing on a Cisco router?

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Answer choices

Why each option matters

Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.

A

Best answer

ipv6 unicast-routing

Correct. This is the required global command.

B

Distractor review

ipv6 enable

ipv6 enable is used at the interface level to enable IPv6 processing, not global routing.

C

Distractor review

ip routing ipv6

This is not valid Cisco IOS syntax.

D

Distractor review

ipv6 route enable

This is not a valid IOS command.

Common exam trap

Common exam trap: answer the scenario, not the keyword

A frequent exam trap is mistaking the interface-level command ipv6 enable for the global command ipv6 unicast-routing. While ipv6 enable activates IPv6 processing on a specific interface, it does not enable the router to forward IPv6 packets between interfaces. This leads to a scenario where IPv6 addresses are configured and active on interfaces, but routing does not occur, causing connectivity failures. Another trap is selecting commands like ip routing ipv6 or ipv6 route enable, which are invalid in Cisco IOS and will not enable IPv6 routing. Understanding the distinction between interface activation and global routing enablement is critical to avoid this mistake.

Technical deep dive

How to think about this question

IPv6 routing is essential for forwarding IPv6 packets between different networks on a Cisco router. Unlike IPv4, IPv6 requires explicit enabling of routing at the global configuration level to activate the router's capability to forward IPv6 unicast packets. The command ipv6 unicast-routing is the global configuration command that enables this functionality, allowing the router to participate in IPv6 routing protocols and forward IPv6 traffic appropriately. The decision to use ipv6 unicast-routing is based on Cisco IOS design, where IPv6 routing is disabled by default to prevent unintended routing behavior. Enabling this command activates the IPv6 routing table and allows routing protocols such as OSPFv3 or EIGRP for IPv6 to operate. Interface-level commands like ipv6 enable only activate IPv6 processing on interfaces but do not enable routing between interfaces. Therefore, without ipv6 unicast-routing, the router will not forward IPv6 packets between interfaces. A common exam trap is confusing the interface-level command ipv6 enable with the global command ipv6 unicast-routing. While ipv6 enable activates IPv6 on an interface, it does not enable routing between interfaces. Another trap is selecting invalid commands like ip routing ipv6 or ipv6 route enable, which do not exist in Cisco IOS. Practically, enabling ipv6 unicast-routing is the first step in configuring IPv6 routing on Cisco routers, ensuring proper packet forwarding and routing protocol operation.

KKey Concepts to Remember

  • The global command ipv6 unicast-routing enables IPv6 packet forwarding and activates the IPv6 routing table on Cisco routers.
  • Interface-level command ipv6 enable only activates IPv6 processing on an interface but does not enable global IPv6 routing.
  • Cisco routers disable IPv6 routing by default to prevent unintended packet forwarding without explicit configuration.
  • IPv6 routing protocols like OSPFv3 and EIGRP for IPv6 require ipv6 unicast-routing to be enabled to function properly.
  • Invalid commands such as ip routing ipv6 or ipv6 route enable do not exist and will not enable IPv6 routing on Cisco devices.
  • Without ipv6 unicast-routing, a Cisco router will not forward IPv6 packets between interfaces even if IPv6 is enabled on interfaces.
  • Enabling ipv6 unicast-routing is a prerequisite before configuring any IPv6 routing protocols or static IPv6 routes.
  • Confusing interface-level IPv6 enable commands with global routing commands is a common mistake in Cisco IPv6 configuration.

TExam Day Tips

  • Watch for words such as best, first, most likely and least administrative effort.
  • Review why wrong options are wrong, not only why the correct option is correct.

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More questions from this exam

Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.

Question 1

A router learns the same prefix from both OSPF and EIGRP. Which route is installed by default?

Question 2

A router shows this output: R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/DR 00:00:34 192.168.12.2 GigabitEthernet0/0 10.1.1.3 1 2WAY/DROTHER 00:00:39 192.168.12.3 GigabitEthernet0/0 Which statement is correct?

Question 3

What is the OSPF metric called?

Question 4

A non-root switch has two uplinks toward the root bridge. One path has a lower total STP cost than the other. What role will the lower-cost uplink have?

Question 5

A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that web browsing to a server by IP address fails, but ping works. Which statement best explains the behavior?

Question 6

A router learns route 198.51.100.0/24 from OSPF with AD 110 and also has a static route to the same prefix configured with AD 150. Which route is installed?

FAQ

Questions learners often ask

What does this 200-301 question test?

The global command ipv6 unicast-routing enables IPv6 packet forwarding and activates the IPv6 routing table on Cisco routers.

What is the correct answer to this question?

The correct answer is: ipv6 unicast-routing — The global configuration command ipv6 unicast-routing enables IPv6 forwarding on Cisco routers.

What should I do if I get this 200-301 question wrong?

Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.

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