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Difficulty: MediumFloating Static Routes

An enterprise router learns the primary route to network 172.16.50.0/24172.16.50.0/24 via internal BGP (iBGP), which carries a default Administrative Distance of 200200. An administrator wants to configure a floating static backup route pointing to next-hop IP 10.1.1.210.1.1.2. Complete the Cisco IOS command below by entering the minimum administrative distance value required to ensure this route functions strictly as a backup path.

Answer:Router(config)# ip route 172.16.50.0 255.255.255.0 10.1.1.2 【201】

Answer

201
A floating static route must be configured with an Administrative Distance (AD) strictly greater than that of the primary route. Since iBGP has a default AD of 200, the static route requires an AD of at least 201 to remain inactive until the primary iBGP route fails.

Step-by-Step Solution

1
Identify the Administrative Distance (AD) of the primary routing protocol.
The primary path is learned via iBGP, which has a default Administrative Distance of 200200.
Cisco IOS prefers routing information sources with lower Administrative Distance values.
2
Determine the required AD relationship for a floating static backup route.
The static route's administrative distance must be higher than the primary route's AD (>200> 200).
If the static route has an AD lower than or equal to 200200, Cisco IOS will install the static route into the routing table instead of holding it in reserve as a backup.
3
Calculate the minimum integer AD value for the command.
The smallest integer greater than 200200 is 201201.
Specifying 201201 at the end of the `ip route` command sets the static route's AD to 201, keeping it inactive until the iBGP route is removed.

Key Concept

Floating Static Routes and Administrative Distance
Estimated Time:1m 0s
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Topics

Floating Static Routes

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