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Difficulty: HardFloating Static Routes

An enterprise router R1 learns the path to a remote branch subnet 10.150.0.0/1610.150.0.0/16 via Internal EIGRP, which has a default administrative distance of 9090. A network engineer intends to configure a secondary floating static route via next-hop IP 192.168.99.2192.168.99.2 to serve strictly as a backup path when EIGRP fails. However, the engineer enters the following command on R1:

`ip route 10.150.0.0 255.255.0.0 192.168.99.2 85`

Which two statements correctly describe the operational impact of this configuration? (Select two.)

  1. The newly configured static route will immediately enter the Routing Information Base (RIB) and displace the EIGRP route as the active path.Answer
  2. To function correctly as a floating static backup route, the static route's administrative distance must be configured with a value greater than 90.Answer
  3. C
    The static route will remain inactive in the routing table until the primary EIGRP neighbor adjacency fails, because dynamic routes take precedence over static routes by default.
  4. D
    Router R1 will perform equal-cost load balancing between the EIGRP path and the static route because both routes point to the same destination network.

Answer

The static route will immediately enter the routing table and displace the EIGRP route because its assigned administrative distance (85) is lower than Internal EIGRP (90). To act as a backup floating static route, its administrative distance must be set to a value greater than 90.
Cisco routers select routes from different routing sources based on Administrative Distance (AD), where lower AD values indicate higher preference. Internal EIGRP has a default AD of 90. Because the static route command explicitly defines an AD of 85, the static route is considered more trustworthy than EIGRP and is immediately placed into the routing table. To function properly as a floating static route, the static route must have an AD set higher than the primary route's AD (greater than 90) so it remains inactive until the primary EIGRP route vanishes.

Step-by-Step Solution

1
Identify the administrative distance of the primary route protocol.
Internal EIGRP has a default Administrative Distance (AD) of 90.
Administrative Distance defines the trustworthiness of a routing information source in Cisco IOS.
2
Analyze the configured static route's administrative distance parameter.
The command `ip route 10.150.0.0 255.255.0.0 192.168.99.2 85` explicitly assigns an AD of 85 to the static route.
The trailing numeric argument in the `ip route` syntax overrides the default static route AD of 1.
3
Compare administrative distances to determine routing table (RIB) selection.
Since 85<9085 < 90, the static route wins route selection over Internal EIGRP and is immediately installed into the RIB as the active route.
Lower AD values are strictly preferred over higher AD values.
4
Determine the necessary administrative distance for floating static functionality.
To float (remain inactive until the EIGRP path fails), the static route must be configured with an AD value strictly greater than 90 (e.g., 95, 130).
Floating static routes rely on a higher AD so they are suppressed while the lower-AD primary route is present in the routing table.

Key Concept

Floating Static Route Administrative Distance Selection
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Topics

Floating Static Routes

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