Cisco CCNA (200-301)IP ConnectivityMedium
An administrator needs to configure a default route on an IPv6-enabled router so that traffic without a more specific match is forwarded to next-hop 2001:db8:1::1 reachable via interface GigabitEthernet0/1. Which command accomplishes this?
- Aip route 0.0.0.0 0.0.0.0 2001:db8:1::1
- Bipv6 route ::/0 GigabitEthernet0/1 2001:db8:1::1
- Cipv6 route 0.0.0.0/0 2001:db8:1::1
- Ddefault-route ipv6 2001:db8:1::1 GigabitEthernet0/1
Show answer & explanationAnswer & explanation
Correct answer: B. ipv6 route ::/0 GigabitEthernet0/1 2001:db8:1::1
The correct IPv6 static default route syntax is 'ipv6 route ::/0 [exit-interface] [next-hop]', using the IPv6 unspecified prefix ::/0 rather than the IPv4 notation 0.0.0.0/0. Including the exit interface is required when the next hop is a link-local or when disambiguation of the outgoing interface is needed.
Why the other options are wrong
- A. This uses the IPv4 'ip route' command syntax with an IPv6 address, which is invalid.
- C. IPv6 prefixes use ::/0 notation, not the IPv4-style 0.0.0.0/0.
- D. There is no 'default-route' command in Cisco IOS; the correct keyword is 'ipv6 route'.
IPv6 Default Static Route
An IPv6 default route directs all unmatched traffic to a specified next hop, configured with 'ipv6 route ::/0 [interface] [next-hop]'.
- ::/0 is the IPv6 equivalent of 0.0.0.0/0
- Exit interface often required with link-local next-hops
- IPv6 routing must be enabled with 'ipv6 unicast-routing'
Memory trick: Double-colon zero slash zero opens every IPv6 door