Forum Moderators: phranque
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I have no inside knowledge of search engine policy, but penalizing a site because it happens to have a backup server would be ridiculous. You have only one domain name and therefore, even though the content on each server is duplicated, it is not duplicated across multiple domains. Search engines see duplicate content on multiple domains as spam - an attempt to appear multiple times in search results for the same search. This is not useful to the search engine user, so it is penalized. But since search engines list Web pages by domain and not by IP address, your duplicate servers don't waste any space in the search results - only one URL is visible.
You might want to post this question in the Google forum in case I'm wrong. If so, Googleguy can correct me - or will gather his staff and go fix the problem.
Another thing you might want to do is to go check the domain registration for some big sites like Amazon.com, ebay, etc. I'll bet they have backup servers!
Jim
The first part sounds like you're using a backup nameserver. No problem, and a good idea. Both nameservers serve the same information (namely that your domain name should point to some specific IP address). When the first nameserver fails, the second will serve the information (and the IP address of your site remains the same).
This will not cause traffic for your domain to go to the webspace on your other host (sine it is at a different IP address). Google will of course not penalize you for using two nameservers that serve the same information.
Are you suggesting that your secondary nameserver will serve a different IP address than your primary? This would work under the theory that if your primary hosting provider fails in some way then both their nameserver and webserver fail, and that there is no time that your primary webserver fails and the primary nameserver continues to serve the original IP address. (or at least that you're OK with that scenerio.) In fact, I see that occur more often. Webservers fail far more often than nameservers, probably just because people are always mucking with them. Not only that, but DNS based backups have to deal with the fact that resolvers may be looking to caching nameservers which have cached old DNS information for your site so the switch-over may not be as quick as you expect.
Now, you should know that this discussion of primary and secondary nameservers is rather flawed anyway since nameservers are not ordered. A resolver is allowed to query the authoritative nameservers in any order, so you would expect that under normal operating conditions that you get traffic to both of your nameservers. If they are giving different IP addresses, then you would expect to get traffic at both webservers.
Sound good because it balances traffic? Well, do you keep any kind of state on your webserver such as a shopping cart? What happens when one user's session gets split between two different webservers? Will your second webserver know all of the contents of their shopping cart just based on the cookies and such? I hope not.
You can certainly use two hosts and two nameservers to provide backup, redundancy, and load sharing, but it's a surprisingly complex subject.
