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Difficulty: MediumFloating Static Routes

A router receives routes to the destination network 10.50.0.0/1610.50.0.0/16 via internal EIGRP (Administrative Distance 9090). An engineer intends to create a floating static route as a backup path and executes the command `ip route 10.50.0.0 255.255.0.0 192.168.12.2 80`. Which outcome occurs as a direct result of this configuration?

  1. The newly configured static route immediately replaces the EIGRP route in the routing table because its Administrative Distance of 8080 is lower than 9090.Answer
  2. B
    The static route remains inactive in the background and only enters the routing table if the primary EIGRP neighbor adjacency fails.
  3. C
    The router installs both routes into the active routing table simultaneously and performs load balancing across both paths.
  4. D
    The command is rejected by Cisco IOS because custom administrative distance values below 9090 are prohibited for static routes.

Answer

The newly configured static route immediately replaces the EIGRP route in the routing table because its Administrative Distance of 80 is lower than 90.
Cisco routers use Administrative Distance (AD) to evaluate route trustworthiness when multiple sources learn paths to identical prefixes. Internal EIGRP has a default AD of 90. Configuring a static route with an AD of 80 makes it more preferred than EIGRP because a lower AD value indicates higher priority. As a result, the static route preempts the EIGRP route immediately in the routing table rather than functioning as a backup.

Step-by-Step Solution

1
Identify the Administrative Distance (AD) of the existing primary route.
Internal EIGRP has a default AD of 9090.
Administrative Distance is used by Cisco IOS to select the best path when multiple routing sources supply routes to the same destination.
2
Analyze the configured AD of the static route command `ip route 10.50.0.0 255.255.0.0 192.168.12.2 80`.
The trailing value 8080 sets the static route's AD to 8080.
The default static route AD is 11, but appending a number at the end overrides the default AD value.
3
Compare the two AD values to determine routing table selection.
Since 80<9080 < 90, the static route is considered more trustworthy than EIGRP.
Lower AD values are preferred. To make a static route a floating backup, its AD must be higher than the primary protocol (e.g., AD of 95 or higher).

Key Concept

Floating Static Route Administrative Distance Requirements
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Topics

Floating Static Routes

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