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Zorluk: ZorIPv4 Static Routing

An administrator is implementing a floating static route on a Cisco IOS router to act as a backup path for a primary route learned dynamically via internal EIGRP (Administrative Distance 90) to the destination subnet 10.100.50.0/2410.100.50.0/24. The administrator executes the following command:

`ip route 10.100.50.0 255.255.255.0 172.16.1.2 90`

While the primary EIGRP route remains active, traffic destined for 10.100.50.0/2410.100.50.0/24 is unexpectedly load-shared across both the dynamic route and the static route. Which configuration change will ensure that the static route functions exclusively as a backup route?

  1. Reconfigure the static route with an administrative distance greater than 90.Cevap
  2. B
    Reconfigure the static route with an administrative distance lower than 90.
  3. C
    Specify an exit interface instead of the next-hop IP address while keeping the administrative distance at 90.
  4. D
    Append the overload parameter to the static route command string.

Cevap

Reconfigure the static route with an administrative distance greater than 90.
For a static route to act as a floating backup route, its administrative distance must be configured higher than the administrative distance of the primary route. Since internal EIGRP uses an AD of 90, configuring the static route with an AD of 90 causes both routes to share the same administrative distance, resulting in unexpected dual-path active insertion. Assigning an AD greater than 90 keeps the static route out of the routing table until the primary EIGRP route fails.

Adım Adım Çözüm

1
Analyze the administrative distance of the primary routing protocol.
Internal EIGRP has a default administrative distance of 90.
Administrative distance determines route preference in the Cisco IOS Routing Information Base (RIB).
2
Evaluate the current static route configuration.
The configured static route explicitly sets an administrative distance of 90, matching EIGRP's administrative distance.
When two routes to the exact same prefix have equal administrative distances, the router treats them as equally trustworthy, leading to unexpected traffic load-sharing or tie-breaking behavior.
3
Determine the requirement for a floating static route.
A floating static route must have an administrative distance strictly higher than the primary route's AD (e.g., 91 or 130).
This guarantees the static route remains inactive in the RIB until the primary dynamic route is removed.

Anahtar Kavram

Floating Static Route Administrative Distance Calibration
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