Multiple (different) domains and canonicalisation

[Sarbs]

Hello,

We've had experience with canonical tags for various domains before, such as tidying up product categories etc...

However, can anyone point me to any guidelines about different domains using canonicalisation. For example:

If I had the following sites, all with identical content -

• exampledomain.com
• completelydifferentdomain.net
• anothertotallydifferentdomain.com

With canonical tags pointing to the first one (exampledomain.com), could this be harmful?

Is it better to 301 redirect the other sites?

Thanks

[Dr-Pete]

Canonicalization is a bit of an "it depends" answer in a lot of cases. If the domains are really identical and if you want to discontinue using the two duplicate domains, then 301-redirects are probably the best long-term bet.

If you need to continue using the other two domains (as landing pages for other marketing campaigns or paid search, for example), then 301s aren't going to be viable, and cross-domain canonicals should be a decent choice. I'd also say that if you just have a small number of duplicates pages (not the entire sites), then canonical tags are a good bet.

The only time I'd be cautious with 301s is if: (1) one of the domains has a bad history or questionable link profile, or (2) you're 301'ing a large number of domains - two domains is probably not an issue. In that cases, canonical tags may be a little safer (people aren't gaming them as much as 301s - yet - so Google isn't quite as suspicious).

[Sarbs]

We have found answers to this:

Nice Q&A article on SEOMoz . Also a whiteboard Friday on cross domain canonical tags, in fact there’s some research they sight by Tony Adams that reckons this is even faster and more effective than a traditional 301.