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Zorluk: OrtaRouting Concepts and Dynamic Routing Protocols

A network engineer is configuring a core router that learns a path to the 10.50.0.0/1610.50.0.0/16 network through multiple routing sources simultaneously: an internal OSPF advertisement, a RIPv2 advertisement, and a manually configured static route. All sources advertise the exact same prefix length. Which path will the router install into its active routing table, and why?

  1. The static route, because static routes have a lower Administrative Distance than OSPF and RIPv2.Cevap
  2. B
    The OSPF route, because dynamic routing protocol updates operate at Layer 2 to bypass IP routing table overhead.
  3. C
    The RIPv2 route, because distance-vector protocols automatically override link-state protocols when hop counts are equal.
  4. D
    All three routes simultaneously in a round-robin load-balancing group across different VLAN broadcast domains.

Cevap

The static route is installed into the routing table because it has the lowest Administrative Distance (AD = 1) compared to OSPF (AD = 110) and RIPv2 (AD = 120) for the exact same destination prefix.
When a router receives multiple routes to the exact same destination network prefix from different routing sources, it uses Administrative Distance (AD) to select the best route. Default AD values are: Static route = 1, OSPF = 110, and RIPv2 = 120. Because lower AD indicates higher trustworthiness, the static route is selected.

Adım Adım Çözüm

1
Identify the advertised destination prefix lengths across all sources.
All three routes offer identical prefix lengths (10.50.0.0/1610.50.0.0/16), so Longest Prefix Match (LPM) ties.
When prefix lengths match, the router evaluates Administrative Distance (AD) to determine trustworthiness.
2
Compare the Administrative Distance values of the competing routing sources.
Static Route AD = 1, OSPF AD = 110, RIPv2 AD = 120.
Lower Administrative Distance values indicate higher administrative preference and trustworthiness.
3
Select the winning route to install in the IP routing table.
The static route with AD = 1 is selected.
The router selects the path with the lowest Administrative Distance.

Anahtar Kavram

Administrative Distance Hierarchy and Route Selection
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