200-301 Question #909: Real Exam Question with Answer & Explanation

Question

Refer to the exhibit. The image server and client A are running an application that transfers an extremely high volume of data between the two. An engineer is configuring a dedicated circuit between R1 and R2. Which set of commands must the engineer apply to the routers so that only traffic between the image server and client A is forces to use the new circuit?

Options

• AR1(config)#ip route 10.10.13.10 255.255.255.255 10.10.10.6
• BR1(config)#ip route 10.10.13.10 255.255.255.128 10.10.10.6
• CR1(config)#ip route 10.10.13.10 255.255.255.252 10.10.10.6
• DR1(config)#ip route 10.10.13.10 255.255.255.255 10.10.10.2

Explanation

To force traffic only between specific hosts to use a new dedicated circuit, host-specific static routes must be configured on the routers, pointing to the next-hop on the new circuit.

Common mistakes.

• B. Using a /25 mask (255.255.255.128) creates a network route that covers a range of IP addresses, not just the specific host. This would force more traffic than just the Image Server's to use the new circuit, violating the 'only traffic between' requirement.
• C. Using a /30 mask (255.255.255.252) creates a network route that covers a range of IP addresses, not just the specific host. This would force more traffic than just the Image Server's to use the new circuit, violating the 'only traffic between' requirement.
• D. While a host route (255.255.255.255) is correct for specificity, the specified next-hop 10.10.10.2 contradicts the implied correct next-hop 10.10.10.6 for the dedicated circuit, as indicated by the correct answer.

Concept tested. Static host routing for policy-based forwarding

Reference. https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_static/configuration/xe-3s/irs-xe-3s-book/irs-static-route-cfg.html

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