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Difficulty: EasyIPv4 Static Routing

Router R1 learns the primary route to destination network 10.50.0.0/1610.50.0.0/16 via OSPF, which has a default Administrative Distance of 110. A network engineer must configure a static backup route to the same network that remains inactive in the routing table until the OSPF route fails. Which Administrative Distance value must be assigned to the static route?

  1. 120Answer
  2. B
    110
  3. C
    90
  4. D
    1

Answer

120
A floating static route functions as a backup path by configuring its Administrative Distance (AD) to be higher than the AD of the primary routing protocol. Since OSPF has an AD of 110, setting the static route's AD to 120 ensures it is kept out of the routing table until the primary OSPF route becomes unavailable.

Step-by-Step Solution

1
Identify the Administrative Distance (AD) of the primary dynamic routing protocol.
OSPF has a primary AD of 110.
Cisco IOS selects routes based on lower Administrative Distance values when multiple paths to the same destination exist.
2
Determine the required AD relationship for a floating static backup route.
The static route AD must be strictly greater than 110.
A floating static route must have a higher AD than the primary route so it remains hidden until the primary route disappears.
3
Select the option with an AD greater than 110.
120 is greater than 110.
Using an AD of 120 keeps the static route out of the routing table during normal operation.

Key Concept

Floating Static Route Administrative Distance Configuration
Estimated Time:45s
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Topics

IPv4 Static Routing

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