Sorry, I'm not seeing the bad URL(s) in the cache. Could you provide a sample Google query that's showing the hijacking URL?

Are you trying to prevent future hijacking or undo the SEO damage done by the previous hijacking? Sorry, I'm not completely clear on what happened or where you're at in the recovery process.

I don't believe domain age is directly factored into DA at all. Of course, it's not uncommon for older sites to have more links, more substantive content, etc., but that's purely a correlation. If you registered a domain 5 years ago and just launched the site yesterday with one page and no links, that site will still have no authority.

Unfortunately, there is no officially sanctioned method for blocking just a portion of a page from the index. As others have mentioned, there are tricks that might do it, but their effectiveness is inconsistent, and most of them will run the risk that Google could treat it as a red flag of some sort. More often, the results just end up being unpredictable (especially with JavaScript) and end up causing additional grief for your developers and visitors.

Most of the time, if you're dealing with substantial amounts of content you don't want indexed, I'd look for other solutions, such as grouping that content or making sure more of your content on any given page is unique. Unfortunately, that depends a lot on why you want it blocked, so it's hard to give a one-size-fits-all answer.

I wouldn't get too hung up on the Moz timeline, since that's only correlated with what Google does, to build a broader model. If Google has crawled/cached the 404 and the page actually is no longer in the index, then that page should stop inheriting and passing link equity. It can get complicated, because sometimes 404s have inbound links and other issues tied to them that can confuse the crawlers. So, I'd say it's situational.

Moz (specifically, OSE) can help you determine what links still exist to those URLs, which really should guide whether you let them stay 404s or 301-redirect them to something relevant. The other aspect of the decision is just whether something relevant exists. If you clearly have built a page to replace the old one then 301-redirect it. If the old page is something that ceased to exist for a reason, then a 404 is probably fine unless that old page had a ton of inbound links. In that case, the 404 has essentially cut off those links.

The problem is that those inbound links are still out there, so it's not that the authority has ceased to exist. It's that you've basically cut the pipe through which the authority flows.

Sorry, I'm a little confused - are you 301'ing to a 404? I'm not really sure I understand the situation.

I think our data is getting refreshed every couple of weeks at this point, but I'm not sure if a 404 will drop a page from MozScape/OSE right away at that point. I suspect 301s may be updated more quickly, since a 404 could be a temporary issue. Once the target of a 301 gets passed the PA, the original page should lose it.

EGOL is essentially correct - DA and PA are measures of ranking power, essentially (they both factor in multiple variables), but we don't currently model things like the likelihood of a link to be spammy - although we're working on that. So, it is definitely possible for a site to have high authority in theory but devalued by Google in practice.

It also depends on whether you mean "trust" in a broad sense or specifically something like TrustRank. Our MozTrust metric was intended to approximate TrustRank, which essentially measure how far a site is from a seed set of trusted sites. That's a way we believe Google has quantified "trust" in the past. I don't believe that PA/DA factor in MozTrust, but I'm not entirely sure on that one.

In terms of link value, DA and PA can both matter, and it depends a bit on the situation - even both metrics are only a small piece of the puzzle. If the numbers are similar and low (like 20/34 or 34/20), I wouldn't obsess about it. It's when they differ quite a bit that you might want to consider both. A weak page on a very strong domain or a very strong page on a weak domain both have potential value as link sources.

It can vary quite a bit. The page has to be recrawled/recached, which can take anywhere from hours to weeks, depending on how much authority the page has. That's usually the big delay. After that, Google may on occasion delay passing authority, but we don't have proof of that (there are just cases where it seems like they do).

If it's just a handful of pages, re-fetch them through Google Webmaster Tools. It never hurts to kick the crawlers.

I certainly think that gradually adding pages and focusing on quality will help. The problem is that the devil really is in the details. The size of your current site, the type of pages you currently index, your link profile, the type of niche/industry you're in... all of these things matter, to some degree. So, what works for one site might be a problem for another.

Easing into it is definitely going to mitigate your risks, and I think focusing on the most high-impact pages while leaving the other filters/sorts/etc. out of the index is a good idea. Whether this strategy is going to provide real value over the time is the bigger question. Ultimately, I think internal search pages have been devalued a lot, even on reputable sites. I've been through this with a former client - they have a perfectly legitimate business model and provide good value to users, but Google sees them as a directory and much of their index is necessarily search results. Over time, even though they've never been penalized, they've just seen a steady decline, because it takes more than that to rank now.

Generally speaking, Google's view of internal search pages has dimmed over time, and they tend to view them as thin. It used to be common practice to use those pages to rank for category and sub-category terms, but Panda has changed a lot of that.

That's not to say it never works, or that if you add enough unique content, you can't create value. Given that your DA is low, though, and it sounds like all the new content you'd be rolling out would effectively be search results within your own site, I'd be cautious.

Yeah, one thing I think is critically important is to try to divorce yourself from your own creation and think in terms of what Google finds valuable. We all think our sites are the greatest and every page we create is a masterpiece, even when we'd ignore or trash the same kind of page on someone else's site. When you're talking about a 100X increase, brutal honesty with yourself is very important.

I'd have to ask about how we specifically measure DA in this case, but the broader answer is "Yes", it can absolutely decrease your authority. There was a time when more pages just mean more opportunities to rank, but that time is long gone, IMO. Even before Panda, there was an increasing risk of dilution - your authority (and even specifically your PageRank) can only spread so thin. If your link profile is relatively weak, and you expand by 100X, each page is going to get less and less authority. You have more theoretical opportunities to rank, but each opportunity has a much smaller chance. Of course, it's more complex than that, but that's the bottom line.

After Panda, the calculation changed a lot. Now, you're not only diluting your content, but if it's thin enough, you risk Google taking action that could harm your entire site. So, EGOL's simple question is critically important. Also, note that "unique" doesn't not mean valuable in Google's eyes (or search users). It's easy to string words together to create something unique, but if that's not adding value it may still be seen as "thin".

It's really tough to say, but moving away from "Let Google decide" to a more definitive choice seems like a good next step. You know which URL should be canonical, and it's not the parameterized version (if I'm understanding correctly).

If you say "Let Google decide", it seems a bit more like rel=prev/next. Google may allow any page in the set to rank, BUT they won't treat those pages as duplicates, etc. How does this actually impact the PR flow to any given page in that series? We have no idea. They're probably consolidating them on the fly, to some degree. They basically have to be, since the page they choose to rank form the set is query-dependent.

I generally wouldn't NOINDEX something that's part of your navigation structure, unless it's a deep layer (and you want to cut off anything "below" it). If you're concerned that they don't have search value, I'd consider consolidating somehow, which I thought was the general plan from the original question. I just don't know that you need all of the content or to get too complicated with the consolidation.

Yeah, I don't think the picture- and video-heavy pages are going to rank all that well by themselves. It's just a question of whether those additional pages are diluting your MLS listing pages (by using similar regional keywords, etc.).

At the scale of a large site, it's hard to tell without understanding the data, including where your traffic is coming from. If it's producing value (traffic, links, etc.), great. If not, then you may want to revisit whether those pages are worth having and/or can be combined somehow. I don't think "combined" means everything on both pages gets put onto one mega-page - you could pick and choose at that point.

That depends on a lot of factors. Consolidating those to one page has advantages, SEO-wise, but you're losing the benefits of the photo page. I lean toward consolidation, but it really depends on how the pages are structured in the navigation, what sort of content and meta-data they have, etc. I'm not clear on what's left on Page A currently, but the biggest issue is probably dilution from the extra pages. Since there are "guide" pages, though, I'm not sure how they fit your site architecture. To remove 200 of them, you may need to also rethink your internal link structure.

That's a trick that used to occasionally work, but there's no evidence for it in the past couple of years. Google has gotten pretty good at understand how pages are rendered and is no longer completely dependent on source-code order. In some cases, they may even view it as manipulative.