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Zorluk: OrtaIPv4 Static Routing

A network administrator intends to configure a backup floating static route on router R1 to reach destination network 10.50.0.0/1610.50.0.0/16 in the event that the primary route learned via OSPF fails. The administrator enters the following configuration command on R1:

`ip route 10.50.0.0 255.255.0.0 192.168.12.2 105`

What is the immediate impact of this configuration on router R1's routing table?

  1. The static route becomes the active route in the routing table because its administrative distance of 105 is lower than OSPF's default administrative distance of 110.Cevap
  2. B
    The static route remains stored as an inactive backup route and will enter the active routing table only if the primary OSPF route fails.
  3. C
    The static route is installed alongside the OSPF route, causing R1 to perform equal-cost load balancing toward destination 10.50.0.0/16.
  4. D
    The command is rejected by Cisco IOS because custom administrative distance values for IPv4 static routes cannot be lower than 110.

Cevap

The static route becomes the active route in the routing table because its administrative distance of 105 is lower than OSPF's default administrative distance of 110.
In Cisco IOS, administrative distance (AD) determines which routing source is preferred when multiple sources provide routes to the same network prefix. OSPF has a default AD of 110. Because the configured static route specifies an AD of 105, which is lower (more trusted) than 110, the static route immediately takes precedence and replaces the OSPF route in the active routing table.

Adım Adım Çözüm

1
Identify default Administrative Distance (AD) values
Default OSPF AD is 110; default Static Route AD is 1.
Administrative distance measures the trustworthiness of a routing information source.
2
Analyze the configured static route parameter
The trailing value `105` in `ip route 10.50.0.0 255.255.0.0 192.168.12.2 105` sets the static route's AD to 105.
Floating static routes require an AD value higher than the primary routing protocol to stay hidden until the primary path fails.
3
Compare AD values to determine routing table selection
105 (configured static) < 110 (OSPF), so the static route is selected and immediately replaces the OSPF route.
When multiple routes to the exact same destination prefix exist, the router installs the route with the lowest administrative distance into the routing table.

Anahtar Kavram

Floating Static Route Administrative Distance Selection
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