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I've heard someone say today that a highly available domain name should be configured using nameservers located in different ASNs. I've however taken a look at the namesservers for google.com and all of them belong to the same ASN. So my question is: What is the best practice? Is there any reason to locate the nameservers in different ASNs?

closed as off-topic by Ron Maupin Jul 9 '18 at 1:38

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Multi-ASN in this case is more of a proxy for a high degree of network resilience. The basic idea is that primary and secondary servers should be deployed in such a way that the loss of even multiple significant infrastructure elements (servers, links, routers, even entire sites) shouldn't result in a condition where no resolvers are online for a given domain. Clearly Google's ASN spans most of the planet, as do their resolvers. They wouldn't gain anything by hosting secondaries with a different carrier. A small shop with a couple of BGP-connected routers in a single office? Likely a good candidate for at least some secondaries hosted elsewhere.

  • Thanks for your explanation. I wonder however what would happen if Google's ASN got revoked? Would it take away their right to participate in the BGP routing, effectively making the entire Google network disappear from the internet? – kjagiello Sep 13 '17 at 6:17
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    I assume that would happen, and that's what the Internet is all about. An AS "is" an entity (carrier, enterprise, content provider, ...) participating, no actually being one of the networks in the mesh of the "network between networks". Google will have taken precautions (read: interconnects and peerings at multiple points in multiple countries) that will make sure that their AS never gets isolated from the other ASs. As long as the company will exist, I would see no reason why their ASN should be revoked, – Marc 'netztier' Luethi Sep 13 '17 at 8:07

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