Refer to the exhibit. Router 1 is connected to router 2 on interface TenGigE0/1. Which interface provides the alternate path to 172.16.200.9/32 when the link between router 1 and router 2 goes down?

Question

Exhibit

Options

• ATenGigE0/1 interface provides the alternate path
• BA backup path must be statically installed
• CTenGigE0/2 interface provides the alternate path
• DA primary path must be manually installed

• A
  3% (1)
• B
  3% (1)
• C
  90% (36)
• D
  5% (2)

Explanation

This question involves IP FRR (Fast Reroute) or LFA (Loop-Free Alternate) path protection, or simply ECMP/alternate path routing. Router 1 has a primary path to 172.16.200.9/32 via TenGigE0/1 (connected to Router 2). TenGigE0/2 provides connectivity to an alternate next-hop that can still reach 172.16.200.9/32 via a different path in the network topology. When TenGigE0/1 goes down, the routing protocol (OSPF, IS-IS, or BGP with fast-reroute) activates the pre-computed alternate path through TenGigE0/2. Option A is incorrect - TenGigE0/1 is the failed primary link, not the alternate. Option B is incorrect - in a properly configured network with dynamic routing protocols, backup paths do not need to be statically installed. Option D is incorrect - the primary path is already installed dynamically and does not need manual installation. TenGigE0/2 is the pre-computed loop-free alternate (LFA) or secondary ECMP path.

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