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What I mean is, I have my clients point their A-Records to an IP address of mine for hosting purposes. Then, when I decide to move data centers, I have to make all of them point their A-Records to a new IP address. I would like to mitigate the risk of this happening by having them point their A-Records to an IP address A that some how routes to whatever IP address B that I want to, so I can easily fail over from one data center to another, or change data centers for whatever reason. Is this possible?

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Why not just have them point their A Records to an A record you control. It'd actually have to be something like a cname record, then you can just change your a record and they wont have to do anything. – ErnieTheGeek May 4 '12 at 18:18
@ErnieTheGeek - can you explain what you mean by an "A record you control". – orokusaki May 4 '12 at 18:20
Basically what becoming wisest is describing to you. – ErnieTheGeek May 4 '12 at 18:49

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There are a few options.

  • Have them use CNAMES instead, so you control the final A record lookup.
  • Manage DNS for them or have access to their DNS management portal, so you can make such changes.
  • Unlikely, but get your own IP block, so when you migrate to DC B, you can move your entire range there.
  • If its just websites, perhaps leave a reverse proxy at DC A, that knows to look for the stuff at DC B.
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They will be using CNAMEs for www, but that doesn't help me with root requests to their domains (e.g. http://example.com), or does it? – orokusaki May 4 '12 at 18:21
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No, you need an A record for the naked domain name, e.g., example.com. Some DNS providers have a concept of DNS forwarding for naked domain names (i.e., in their control panel you say foo.com forwards to bar.com, and they will poll the A record for bar.com, and present that IP as the A record for foo.com), so you get some redirection, but it may not help in your case. – cjc May 4 '12 at 18:27
@cjc - thank you. And, darn it! – orokusaki May 4 '12 at 18:32

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