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Difficulty: MediumFloating Static Routes

Router R1 learns the destination network 10.50.0.0/1610.50.0.0/16 dynamically via internal EIGRP, which has a default Administrative Distance (AD) of 90. A network administrator wants to configure a floating static route pointing to next-hop 192.168.12.2192.168.12.2 to serve as a backup path when the EIGRP route fails. Which two conditions or behaviors apply to this floating static route implementation? (Select two.)

  1. The floating static route must be configured with an Administrative Distance value greater than 90.Answer
  2. The floating static route will be placed into the active routing table only when the primary EIGRP route is removed.Answer
  3. C
    Configuring the static route with an Administrative Distance of 80 ensures it acts as an inactive backup route during normal operation.
  4. D
    Both the EIGRP route and the floating static route will be installed into the routing table concurrently to perform unequal-cost load balancing.

Answer

To configure a functional floating static route for an EIGRP primary path, the static route must specify an Administrative Distance greater than 90 (the default EIGRP AD). Consequently, the backup route will only be installed into the active routing table when the lower-AD EIGRP route disappears.
A floating static route acts as a backup mechanism by using an Administrative Distance (AD) higher than that of the primary route (in this case, EIGRP AD of 90). Cisco IOS populates the active routing table with the lowest AD available; thus, the static route stays out of the routing table until the primary route fails and is withdrawn.

Step-by-Step Solution

1
Identify the Administrative Distance (AD) of the primary routing protocol.
Internal EIGRP has a default AD of 90.
Floating static routes rely on AD comparison to remain dormant until the primary route fails.
2
Determine the required Administrative Distance for the backup floating static route.
The static route's AD must be set higher than 90 (e.g., 95 or 130).
If configured with a lower AD (such as 80 or 1), the static route would override the EIGRP path during normal operation.
3
Analyze how Cisco IOS handles routing table selection for multiple sources.
Only the path with the lowest AD is placed in the active routing table.
The floating static route remains inactive in the background and is only installed when the EIGRP prefix is removed due to network failure.

Key Concept

Floating Static Routes and Administrative Distance
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Topics

Floating Static Routes

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