Designing Cisco Enterprise Networks (ENSLD) — Question 15

An engineer is upgrading a company's main site to include a connection to a second ISP. The company will receive full Internet routing tables from both ISPs via
BGP. The engineer must ensure that the company does not become a transit autonomous system. Which solution should be included in this design?

Answer options

• A. Tag incoming routes from both ISPs with BGP community no-export.
• B. Lower the MED for updates sent to the secondary ISP.
• C. Use a route-map to prevent all prefixes from being advertised to either ISP.
• D. Modify the local-preference for routes incoming from the primary ISP.

Correct answer: A

Explanation

The correct answer is A, as tagging incoming routes with the BGP community no-export prevents those routes from being advertised to other autonomous systems, thus keeping the company from becoming a transit AS. The other options do not effectively address the requirement to prevent transit traffic; lowering MED, using route-maps, or modifying local-preference does not inherently stop the routes from being advertised outwards.