如何为VIP交换+的CNAME不是IP交换+ A记录好？ [英] How is VIP swapping + CNAMEs better than IP swapping + A records?

问题描述

我在更新我的DNS设置使用所有的CNAME而不是A记录，因为我需要临时和生产之间的VIP互换支持的中间。我不能使用记录，是因为这给将要改变每个部署贵宾的依赖。

I'm in the middle of updating my DNS setup to use all CNAMEs instead of A records, because I need support for VIP swaps between Staging and Production. I can't use A records for this because that puts a dependency on a VIP that will be changing for each deployment.

previously，我用的是因为通配符和基础域支持A记录 - 我可以映射mydomain.com和所有子域的VIP，一切只是工作。

Previously, I was using A records because of wildcard AND base domain support - I could map mydomain.com and all subdomains to the VIP and everything just worked.

的CNAME使这个有点复杂，但并非不可能。

CNAMEs make this a bit more complicated, but not impossible.

我的问题（s）是 - 与VIP互换，该网站网址（mysite.cloudapp.net）需要从指向原来的VIP改变，新的VIP，对吗？如果是这样，不DNS需要反正传播？碰巧的是有 mysite.cloudapp.net 指向原来的VIP缓存DNS记录怎么办？是不是还有一个延迟的传播，并有机会，虽然这种传播发生的请求将被转发到老VIP？

My question(s) is - with VIP swaps, the site url (mysite.cloudapp.net) needs to change from pointing to the original VIP, to the new VIP, right? If so, doesn't DNS need to propagate anyways? What happens to all of the cached DNS records that have mysite.cloudapp.net pointing to the original VIP? Isn't there still a delayed propagation, and a chance that requests will get forwarded to the old VIP while this propagation occurs?

推荐答案

一个VIP互换是Azure中的路由器/负载均衡，而不是外部DNS变化的内部变革。他们只是路由流量从一个内部[组]服务器[S]到另一个，而不是去。因此，对于mysite.cloudapp.net的DNS信息不会有任何变化。因此势必mysite.cloudapp.net（和CNAME'd由你）的人通过IP访问的变化会立即看到变化的VIP掉就完成了。

A VIP swap is an internal change to Azure's routers/load balancers, not an external DNS change. They're just routing traffic to go from one internal [set of] server[s] to another instead. Therefore the DNS info for mysite.cloudapp.net doesn't change at all. Therefore the change for people accessing via the IP bound to mysite.cloudapp.net (and CNAME'd by you) will see the change as soon as the VIP swap is complete.

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