When a site has Internet connectivity with two different ISP's, which two strategies are recommended to avoid becoming a BGP transit site? (Choose two.)

Question

Options

• Aaccept all inbound routes from ISPs
• Badvertise all routes to both ISPs.
• Cfilter routes inbound from the ISPs.
• Dfilter routes outbound to the ISPs.
• Euse a single service provider.

• A
  76% (22)
• B
  14% (4)
• C
  3% (1)
• E
  7% (2)

Explanation

A BGP transit site is one that carries traffic between two external ASes. To avoid this: (A) Accept all inbound routes from ISPs so you have full routing tables and can make optimal local forwarding decisions without relying on a default route through the other ISP. (D) Filter routes outbound to the ISPs, advertising only your own locally-originated prefixes to each ISP-never re-advertising prefixes learned from one ISP to the other. This outbound filtering is the critical control that prevents your AS from being used as a transit path. Option B (advertise all routes to both ISPs) would make you a transit site. Option C (filter inbound) would limit your own routing visibility. Option E (single ISP) eliminates dual-homing entirely.

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