A network engineer is configuring router R1 to maintain redundant connectivity to an upstream ISP. R1 currently learns a default route () via OSPF, which has a default Administrative Distance of 110. The engineer needs to configure a floating static default route using the next-hop IP address over a secondary link so that it serves strictly as a backup if the OSPF path fails. Which TWO of the following statements accurately describe the configuration or operational behavior of this floating static route?
- The command `ip route 0.0.0.0 0.0.0.0 192.168.12.2 120` correctly configures the floating static route with an administrative distance higher than OSPF.Answer
- The configured floating static route remains in the running configuration but is excluded from the IPv4 routing table while the OSPF default route is active.Answer
- CThe command `ip route 0.0.0.0 0.0.0.0 192.168.12.2 90` creates a valid floating backup static route for the primary OSPF path.
- DWhen the primary OSPF link fails, Cisco IOS dynamically alters the administrative distance of the static route from 1 to 120 to activate it.
Answer
The correct statements are that `ip route 0.0.0.0 0.0.0.0 192.168.12.2 120` correctly configures the floating static route, and that the floating static route remains in the running configuration but is excluded from the active IPv4 routing table as long as the primary OSPF default route is active.
A floating static route acts as a backup path and must be configured with an Administrative Distance higher than the primary route protocol (OSPF AD 110). Using `ip route 0.0.0.0 0.0.0.0 192.168.12.2 120` properly assigns an AD of 120. Because Cisco IOS installs only the path with the lowest AD into the routing table, the static route is held in the running configuration and only populated into the IPv4 routing table if the OSPF default route is removed.
Step-by-Step Solution
Key Concept
Floating Static Routes and Administrative Distance