Rel=Canonical URLs?

[visionnexus]

If I had two pages:

PageA about Cats

PageB about Dogs

If PageA had a link rel=canonical to PageB, but the content is different, how would Google resolve this and what would users see if they searched "Cats" or "Dogs?"

If PageA 301 redirected to PageB, (no content in PageA since it's 301 redirected), how would Google resolve this and what would users see if they searched "Cats" or "Dogs?"

[DiamondJewelryEmpire]

is there any particular reason do you want to accomplish it? Can you please tell us what are you trying to achieve.

[visionnexus]

I'm trying to understand the deep context of how Google (and others) treat rel=canonical tags.

There are a few situations that becomes relevant to understand how it works (rather than just code and pray):

1. If we are 301 redirecting PageA, but PageB still has rel=canonical of the URL of PageA, will Google still have PageA as its index?  One reason may be, the URL of PageA is more attractive (URL friendly).
2. We want to know the "delta" of how much content does Google determine as "duplicate content" when Google chooses to use the rel=canonical instead of the natural URL.  I'm suspecting that people may be abusing this, creating a hundred variation of the same page but using one rel=canonical.
3. Some of our 301 redirect work is affected by this because the client doesn't want the new URLs indexed yet.
4. Some legacy CMS tracking/systems that generates funny URLs (it increments each time you make an edit.  So a url like PageA.php becomes PageA.php?version=2, this drives us nuts) is causing a lot of duplicate content - but their CMS sometimes does some wacky 301 forwards.  We need a temporary solution until we can fix the programming logic of the CMS.

[KeriMorgret]

rel=canonical is one of the things google will not always follow, if they think it may be implemented wrong. Barry Schwartz reported from SMX West on a slightly different question about implementation (paginated results) at http://www.seroundtable.com/seo-canonical-pagination-13094.html. The following excerpt should apply to your situation (emphasis mine). I have seen other reports too where Google has determined that canonical wasn't implemented correctly and ignored the instruction.

Not only that, if you do, Google may ignore it because Google uses methods to determine if the canonical tag command is actually something valid for that case. So if you canonical page 2 to page 1 and page 2 is not similar enough to page 1, Google may ignore your canonical tag.

[AU-SEO]

would Google ignore your canonical tag in totality or for only the pages implemented incorrectly?

[KeriMorgret]

I don't know on that. This is an older question -- you might try asking this as a separate new question, where more people will see it.