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Difficulty: MediumIPv6 Static Routing

A network administrator is establishing a backup default route on a Cisco IOS router. The primary default route is currently learned dynamically via OSPFv3 with an administrative distance of 110. The administrator wants to ensure that the backup path towards the next-hop global unicast address 2001:db8:200::2 is used only if the primary OSPFv3 route fails. Which command correctly achieves this objective?

  1. ipv6 route ::/0 2001:db8:200::2 130Answer
  2. B
    ipv6 route ::/0 2001:db8:200::2 90
  3. C
    ipv6 route ::/0 fe80::2 130
  4. D
    ipv6 route 0.0.0.0/0 2001:db8:200::2 130

Answer

ipv6 route ::/0 2001:db8:200::2 130
The correct command uses the IPv6 default route prefix ::/0, targets the global unicast next-hop address, and assigns an administrative distance of 130 (which is greater than OSPFv3's AD of 110), successfully floating the route until the primary path fails.

Step-by-Step Solution

1
Identify the IPv6 default route prefix notation.
The IPv6 default route representation is ::/0.
IPv6 default routes represent all possible destination IPv6 networks using the all-zeros prefix with a length of zero.
2
Determine the required administrative distance for a floating static route.
Set an administrative distance higher than 110 (e.g., 130).
A floating static route must have an administrative distance higher than the primary routing protocol (OSPFv3 AD = 110) so it remains inactive until the primary route fails.
3
Validate next-hop addressing syntax in Cisco IOS.
Using global unicast address 2001:db8:200::2 directly is valid, whereas link-local next hops mandatory require an exit interface parameter.
Cisco IOS requires explicit interface designation only when using link-local IPv6 addresses as next hops.

Key Concept

Floating IPv6 Static Default Route Configuration
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Topics

IPv6 Static Routing

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