How to setup a backup NameServer?

[Dave Warren]

On 2014-05-03 18:15, houguanghua wrote:
> These zones are not owned by ISP, such as: yahoo.com, facebook.com...
> If such backup dns server is ready, ISP will talk to these WEB sites 
> to keep synchronization with their authority NSs.
> It's maybe a huge project.

Do you actually expect to get a zone transfer from all of them? I'd be 
amazed if any is willing.

And if any were willing, why bother setting up a "backup" at all, just 
serve the zone(s) authoritatively all the time and don't waste time 
doing queries for data you already have on-network. But again, I doubt 
they have any incentive to cooperate since there's no advantage to them 
(or you, or your customers for that matter)

While we're on the topic, what's the point? If you have connectivity, 
you can make a reliable DNS infrastructure with normal resolvers and 
caches via a number of different methods. Anycasting within your network 
might be a good choice in a large environment. If your connectivity is 
so badly interrupted that you can't pull off DNS queries against 
authoritative servers, there's little value to keeping DNS up since 
everything else is basically down at this point.

-- 
Dave Warren
http://www.hireahit.com/
http://ca.linkedin.com/in/davejwarren

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