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I just check BGP toolkit of a particular IP and found that it's announced by two different ASes (AS42708 and AS37560). Here: http://bgp.he.net/ip/46.246.63.251

However, AS37560 with more specific prefix is widely accepted. For instance, I check it with https://asn.cymru.com/, the result returns only AS37560 instead of both or AS42708.

So my question is that will route to 46.246.63.251 from the entire Internet change to use path via AS42708 if AS37560 went down? Or the IP 46.246.63.251 just becomes inaccessible if AS37560 went down.

Thank you!

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Traffic always follows the most specific (longest) route entry to its destination. So, any network knowing both the 46.246.32.0/19 route from AS37560 and the 46.246.0.0/17 route from AS42708 will prefer the former.

If the route from AS37560 gets withdrawn for some reason, the remaining route (via AS42708) will become the preferred route, assuming no other more-specific routes are available.

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  • Traffic does not always follow the longest route. Rather, the routing table, using defaults, prefers the route with the longest prefix.
    – Ron Maupin ♦
    Commented Mar 31, 2015 at 0:52

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