one domain, 2 IP's

will google not like it?

[xy123]

For purposes of resilience my webserver is about to have 2 IP addresses. A 2nd IP is being added because my ISP has another server on the same subnet as my primary IP thats receiving frequent DDoS attacks, taking down my site and everything else on the same subnet. The idea is to add a 2nd IP interface on a different subnet, running a secondary nameserver that resolves addresses to the second IP; this will get used when the primary IP is down. [hope this description makes sense; not a network guru]

The question is: will google have any problems with this? Is there any risk of a penalty because it thinks something funny is going on - the same hostname resolving to different IP's depending on the time of day?

[hitchhiker]

My 2 pence:

As far as I know Google uses a similar technique with a very short DNS cache time.

I would imagine Google would probably cache the first IP it sees (whichever that is) and spider the same IP from then on until it decides it's changed.

[dwilson]

I suspect hitchhiker is right about the caching. And Google would not penalize a domain for running multiple IP's. All the big sites (like Yahoo! and Microsoft) do it.

Having dealt with server availability issues before, I'm not sure the plan will solve the problem for you, but I hope it does.

The issue is that other people cache that DNS entry too ... so you may not get the switchover to the new numbers nearly as cleanly as you would like.

When I was concerned about switching, it was b/c we were having trouble with our ISP going down. We wanted a way that we could be accessed on an IP on either of 2 blocks in case one ISP went down -- then the second one would take the load. Straight round-robin DNS will not do this. It must be used in conjunction with BGP (Border Gateway Protocol) on your router & those of your ISP's.

We switched to a more stable, more responsive ISP, so never needed to implement the plan I worked out. More economical ... but kind of a shame. I would have liked to see it set up.

[xy123]

Thanks for the replies. DNS and BGP is not really my field but I do understand that the caching issues dont make this a good solution. For the time being I will switch to a different, single, IP with the same ISP and see how things proceed. Suspect this is all to do with a specific server they host that is being persistently attacked, bringing down everyone else on the same wire.

[lazerzubb]

Similar thread that we had not so long ago, very good.
Effects on Google Ranking by using Virtual/Shared Hosting [webmasterworld.com]