I have site www.example.com which someone previously configured with wildcard DNS records and with no 301 redirects. As you may have expected, Google's index is now full of garbage like w.example.com, pop.example.com, ns1.example.com, foobar.example.com, etc. All of the indexed subdomains are almost exact copies of the main domain, duplicating every content from the latter one.I've set up 301 redirects if requests come from everything except www.example.com, but seems that it is not enough because after almost three months since the redirects where set up, all the incorrect subdomains still pile up on Google's index.So the question is: what could I do to speed up this cleanup process?I have heard of sitemap assisted redirects, but some people suggest that this approach is not viable, since Webmaster Tools may reject sitemaps containing URL's causing redirects.
Cleanup incorrectly indexed subdomains due to wildcard DNS
seo;google;sitemap
The 301 redirects should be resolving this issue but if you do not think that is working you can try also using canonical URLs to resolve this. By giving each page on the main site a canonical URL you will be telling Google that URL is the main URL that you want indexed for that content. Any other URL that pulls up that page should be considered a duplicate of that page and to only consider that page for indexing and ranking purposes.