Cisco CCNA (200-301)IP ConnectivityMedium
A company's primary path uses OSPF (AD 110). An administrator wants to configure a backup static default route that is only installed in the routing table if OSPF fails. Which command achieves this?
- Aip route 0.0.0.0 0.0.0.0 203.0.113.1 metric 200
- Bip route 0.0.0.0 0.0.0.0 203.0.113.1 1
- Cip route 0.0.0.0 0.0.0.0 203.0.113.1 200
- Dip default-gateway 203.0.113.1
Show answer & explanationAnswer & explanation
Correct answer: C. ip route 0.0.0.0 0.0.0.0 203.0.113.1 200
Appending a value after the next hop in an 'ip route' command sets that route's administrative distance. Setting it to 200, which is higher than OSPF's default AD of 110, makes it a floating static route that only appears in the routing table if the OSPF route disappears.
Why the other options are wrong
- A. 'metric' is not valid syntax in an IPv4 static route command; the trailing number sets AD, not a separate metric keyword.
- B. An AD of 1 is the static route default and would always be preferred over OSPF (AD 110), defeating the backup purpose.
- D. 'ip default-gateway' is used on Layer 2 switches or routers without IP routing enabled, not for floating static routes.
Floating Static Route Syntax
Adding a numeric value after the next hop in an 'ip route' command overrides the default administrative distance (1), allowing the route to 'float' as a backup behind a preferred dynamic protocol.
- Syntax: ip route <destination> <mask> <next-hop> <AD>
- Default static AD is 1 if omitted
- AD value must exceed the primary protocol's AD to act as backup
Memory trick: Set the AD higher so the static route floats until the primary sinks.