Q: (privacy requested for obvious reasons)
Hi OWG, for some odd reason, Google has suddenly started spidering our site under the wrong domain name. The home page and a couple of others have been spidered under XXX.co.uk while the rest are under the original domain of yyy.co.uk. We really are at a loss as to why this has happened, can you help please, as yyy.co.uk is just an old domain name that we foreward to our real site.
A: No problem! This often happens and is a timebomb waiting to happen in many cases. It is a way of setting yourself up to be knocked down, due to poor redirection of domains.
On checking the header responses for each domain, it became clear that they were both showing a 200 OK header response! This is absolutely not good as you run the risk of what has just happened to you.
If you are forwarding a domain to another domain you really must use a 301 redirect, on Apache this is simple and if the domain has never been used, it is a straight single line. If on windows, then again it can be done using header redirect, or ISAPI rewrite.
What has happened in this case was that the redirected domain sat there merrily minding its own business for a few years, until some kind soul pointed a nice juicy authoritative link to the wrong version. Google took one look at this link and thought YIPEE new content. Then, it realised that it was in fact content it already had, and it shared up the pages between both domains, based on the ‘importance’ of each version of the page (PageRank is Google’s definition of importance)!
Set up the 301 redirect, and all will be well again, only this time, as pages have been spidered, you will need to use a 301 redirect match. Here is some good information about Apache redirect match good luck.
Technical issues like this are commonplace, I don’t think a day goes by when i don’t come across a problem that is technically based, often canonicalisation is made worse by actions taken by the individual, or well meaning individuals who sadly, have done more harm than good.