Mendel ✍️ » Ammon
Thanks for your answer. Can you expand though? How do you interprete the quote from Google?
Ammon 🎓 » Mendel
The article covers the change of address tool, and as such, both domains need to be registered to the same Google account.
That's not you, so NONE of that applies.
Google are a domain registrar, and maintain a bunch of public Domain Name System (DNS) servers. They know the domain changed hands, and will learn as soon as there is new activity on the domain that they check out that it no longer redirects, and is no longer owned by the same person.
That's it.
Marvin » Ammon
Interesting. I get that you're replying with context to the site change tool on Google Search Console (GSC), but how do how do you view the Op's question more generally?
If domain A was 301 to domain B for 180 days. You then remove that redirect and 301 domain A to domain C, is domain A still carrying any Pagerank left to pass on to domain C, or has it all been depleted and permanently passed on to domain B?
Logic tells me that domain A would no longer have any Pagerank left to pass on, as domain B now holds it. Based on John Muellers answer on this, granted he was talking about redirect chains, but the logic applies:
"For the most part that is not a problem. We can forward PageRank through 301 and 302 redirects. Essentially what happens there is we use these redirects to pick a canonical. By picking a canonical we're concentrating all the signals that go to those URLs to the canonical URL."
Essentially, domain B is now the canonical with all of the Pagerank passed on from domain A, therefore the 301 should be B > C rather than A > C.
If it were the case that domain B permanently received the Pagerank from domain A, yet domain A still holds its original Pagerank (and so does domain B ), then we've effectively duplicated 2 sites with equivalent Pagerank. That could easily be open for abuse?
Thoughts?
Ammon 🎓 » Marvin
Canonicals are determined, in large part, by the link structures, and which URL appears to be the primary one links point to, with a heavy override for how the server responds to requests for those URLs (e.g. redirects, errors, etc).
Once the links, or the redirects, change, so does Google's calculation.
When links to your links change in weight, so does Google's calculation.
The link graph is relative to all other known links, that's how the PageRank system works. If you are familiar with the original papers and patents, pay special attention to the convergence, how and when the reiterative calculations end.
Even if Google were to write in their own database of links some address other than that actually found, that would get overridden and recalculated on the next crawl cycle. i.e. if the situation changes, so does the calculation.
Marvin » Ammon
Thanks! The recalculation makes sense but I would have assumed that Google kept a database of canonical URLs that they kept permanently.
So if we had an external-link to domain-A and that is now canonicalised to domain-B, that would be the case permanently (permanent 301 redirect?). So I would assume that Google skips domain-A and has permanently transferred that PageRank (PR) to domain-B.
The reason why I make that assumption is because there have been plenty of cases where I've made internal URL 301's or domain 301's, and the original URL/domain had been lost/dropped but everything held up.
An example:
I purchased domain A (live website with 800 powerful links), 301 it to domain B and domain B ranks pretty much overnight in a competitive niche (cbd), with domain A's pagerank, presumably. I then redirected domain B to domain C (rebrand) and domain B's rankings transferred over to domain C as expected. Keep in mind this is all being sustained by the Pagerank that came from domain A originally with no additional links.
Domain A gets dropped and expired at some point without me noticing.
Wouldn't that mean that whatever Pagerank B or C had would have died with it, since Google's crawl wouldn't lead to domain B or C and they'd have to recalculate? I didn't build any new links to them, they were sustained entirely by domain A's pagerank.
In that scenario, it seems to me that either domain C now holds the pagerank of domain-A and is sustaining itself without the redirect 301 from domain-A.
Now to your point, Google may still see domain C as the Canonical URL of domain-A because domain-A is a dead domain, therefore domain-A can't possibly be the canonical. Are you then saying that were we to revive domain-A, Google re-crawls an external link pointing to domain A, follows it and sees domain-A is Live WITHOUT a 301 to domain-B/C – that is when Google would recalculate and override their own database of links? And if that were to happen, all Pagerank would then go back to domain-A, and we would see domain-B/C die (provided all the PageRank they have is borrowed from domain-A)?
Ammon 🎓 » Marvin
Remember that just because Google can't grab a URL they don't immediately drop that URL, in case it is simply a server being down for maintenence, or through digg effect, etc, etc. So what server response Google got from domain A may simply mean Google continue to refer to the last known version for a while and see if it comes back.
Marvin » Ammon
Sure, 100 reasons why the site may be inaccessible for a while, which is probably for the same reason why Google advises that the redirect be maintained for at least 180 days. I assumed that after 180 days, the PageRank is permanently transferred, rather than just temporarily transferred.
In my example above, it was permanently dropped, no ill-effects so far. I'm testing another one atm, a DR63 domain-A that initially boosted domain-B and was in place for 3 years, I dropped it from pointing to domain-B about a month ago and just pointing it to domain-C now. So far, it seems that domain-B hasn't seen any negative effects (from pulling away all those links), and domain-C hasn't seen any positive effects either. Almost as if domain-A is now completely Pagerank-less.
With that said, I do see the backlinks of domain-A on domain-C's Google Search Console (GSC) link index now, so maybe it's just a question of time.
Ammon 🎓 » Marvin
Ask yourself this: Google are a domain registrar, and over the years they have created and then dropped all kinds of products and services. In other words, they are really, really well aware that things change. They've bought up more than their fair share of other companies and domains. So, knowing all of that, are they going to allow anyone to buy a domain, redirect it for 6 months, and forever after whatever was there in that six months will always apply?
Of course not, right. So, the only question is what/which triggers of changes will they react to. My bet is literally any. That the 180 days of a thing staying the same means they no longer work it out from scratch every single time, but the moment *anything* changes, they'll start recalculating.

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Marvin » Ammon
Well I'm not saying it'll forever apply, as things change. But let's say 100 links point to domain A and domain A is 301 to domain B. The Key words here is "permanent redirect which transfers PR" which I could equate to "permanent transfer of pagerank".
So let's assume that all of the links that were previously attributed to domain A is now permanently attributed to domain B (skipping A altogether). If Google recrawls those 100 links and find out it's actually only 80 links now, then recalculation would be done for sure, but in attributing it to domain B. So the recalculations never stop, but the canonical target can permanently change – unless domain B is once again 301 to another domain as canonical.
If domain B were to 301 it back to A, then I would assume that a recalculation would be done again to attribute those links back to domain A.
Here is another example, which explains why I think what you're suggesting could be a massive loophole.
A large company(A) acquires another company(b), they 301 all of company B's pages into pages of company A thus consolidating all the links into company A (company B has 5000 links).
5 years that 301 exists and one day they forget to renew the domain subscription for domain B (Mueller in fact implied you can let go of the domain after x time the 301 has been in place). Domain B is back in the market, an SEO snaps it up, rebuilds the entire site and potentially steals the 5000 links away from domain A, being credited back to domain B. Assuming of course there was no links decay which is very unlikely.
I'm dealing with this exact scenario now. For some reason, a large international company forgot to renew a domain they previous acquired(company acquisition) and only had the 301 in place for 6 months. If your theory is true, that company stands to lose over 4000 links worth of PR. Of course they'd be losing all the referral traffic from those links too so it's a silly mistake regardless.
Ammon 🎓 » Marvin
No. My theory is that the instant Google pick up that either the domain registration details have changed, or more importantly, any change in how the server responds occurs, they will update to what the links say now.
Now that doesn't mean that you can't buy expired domains with a ton of links pointed at them and get huge value from them. There have been SEO users exploiting exactly that for close to 2 decades. But the idea that Google won't recalculate if the previous redirect had been there for a while, when that while was ONLY mentioned in regard to a specific tool in a specific context, is not at all credible.
Marvin » Ammon
Well SEO users have been taking advantage of expired domains forever but usually that's under the assumption that the expired domain still carries its pagerank and it hasn't been passed on to another domain. One of the most common items on a checklist (other SEO users) for buying expired domains for Pagerank is to ensure it hasn't previously been redirected, but I can't say I've seen any case studies or official word on this for them to base that recommendation on.
Your theory might very well be correct. I do think however that 301 is much like a game of catch, except pagerank is the ball. A domain can lose the PR/ball, if it's passed it to another. And it doesn't mean that no recalculation is ever done again, recalculation is done but the new score from that recalculation is given to the new owner, the one it was permanently transferred to.
Ammon 🎓 » Marvin
Permanence really doesn't occur in any paper or patent, or indeed, in the thinking of those who create them, the guys who engineer the search engines.
Marvin » Ammon
Permanent is a loose term, as permanent as it can be. If we 301 domain A to B then it's permanent for that time, until perhaps we 301 B back to A or to C, so yes, nothing is permanent. The question is which is the trigger for breaking the current state?
I also think that your theory might run counter to Muellers quote?
"John addressed the question at the 24:11 mark in the video, "For how many months or years, we should keep 301 redirect rules OR can we remove redirect rules after some time. Will removing the rules have a negative impact? Will Google again start showing old urls in search results as indexed after removing the rules?"
He said:
Theoretically, a 301 redirect is a permanent redirect, so you can keep that forever. Practically, it's not reasonable to keep something like that forever.
In practice, if we recognize this as a permanent redirect, we try to keep that in mind for the future as well. So if you've moved your site, and we are able to recognize that within an year or so, then at some point, you can take that redirect down. One must keep in mind that if the 301 redirect is removed, and the links to the old version of the URL exist, then it might show that too."
Why would John advise for anyone to take down a 301 after a year if it could result in potentially losing all that pagerank?
Imagine this scenario:
(5000 links) 301 to (0 links).
1 year later, removes the redirect per John's advise, assuming they didn't build any new links during that year. By your theory, would be back to 0 links, all that pagerank previously transferred to them has been lost, as nothing is permanent, and server response has changed. We could go 1 step further and assume an SEO registered and reignited the 5k links for that domain.
Seems like disastrous advice?
Ammon 🎓 » Marvin
John doesn't give SEO advice. He is not an SEO consultant. He gives advice on how Google would like you to behave. There is a difference that you always need to remember.
To Google, if you had that redirect there for a whole year, and still didn't get any links, then as far as they are concerned, the domain deserves zero links as it is no longer earning them. End of story.
Google don't want you exploiting a different time in the past and a lot of outdated old links. They'll HAPPILY see you lose all that PageRank. In fact, you can be sure they'll have all sorts of algorithmic steps to discount old links from pages that are no longer current, and no longer updated. So yeah, he could well advise that.
Marvin » Ammon
I don't think that's a fair assessment. I mean Mueller will say things that's favourable to Google and not necessarily to SEO users but he doesn't usually give advice that could outright ruin a business.
In the example above, it could be something as simple as a brand name change. Let's put in another scenario:
is my company I've owned for 10 years. It's earned 5000 links during that period. I decide to rebrand it to I do a 301 as standard, perhaps earn 500 natural links during that year which is respectable growth.
I drop the 301 per John's advise and overnight, I'm down from my 5500 hard-earned natural links to 500 links. Nothing shady there, just figured I don't need to keep paying for the old domain and John said we could drop those 301's.
I suspect that a crash from 5500 links worth of PageRank (PR) down to 500 links worth of PR would not do any good for the site.
Seems like terrible advise and as misleading as Google can be sometimes, I doubt they would be this intentionally misleading. Course I could just be naive.
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Ammon 🎓 » Marvin
On the contrary. If you build a business on malware, exploitation, cheats, etc, then Google employees, including John, will happily ruin your business. They actively work towards ruining such every single day.
If they see you manipulating links, they'll ban your site, not caring one whit whether that results in job losses, but probably hoping it will.
Well, if your domain is reliant on old links from an earlier iteration, a simpler time, and in the past year all links have gone to better competitors that have come along, none of your old links got updated anywhere on the entire internet, then to them, that's EXPLOITING a weakness in the algorithm. They don't give a damn if you starve.