I have a very popular site. Site primarily focuses two countries India and Australia. For Indian customers domain is mysite.com and for Australians its au.mysite.com. I would like to do a IP based redirection so that in Australia people can see au.mysite.com while they typein mysie.com. For other parts of the world; visitors will see mysite.com What is the impact of this kind of IP based redirection in SEO? I know ebay, monster, google are doing that but they redirect to a different domain (google.co.in) while in my case I will be redirecting to sub domain.
Google treats sub-domains as individual domains, so I don't see what the problem will be. Even so, you have completely different content on each site because its 2 different languages you're have; you want have to worry about duplicant content.
So, there is no problem you can do the 301 redirect as this are completely different sites to Google.
If you do an IP redirect Google will just redirect the same as a user from the US unless you don't employ the redirect for Googlebot.
You start with a database like this then install a php script to detect the IP, look up the country and set a cookie. I will be blogging about this later in the week and will write a script for it.
I got following reply from one of SP members. Is it ok? "I imagine this would have little effect on SEO. Google's bots will generally have non Australian IPs, so will just see the default mysite.com page, as they do now. If a bot happened to have an Aussie IP, and saw the redirection, it would probably just throw the site up for manual review at worst, in which case a human could clearly see that the redirection is for your users, not for the SEs."