there really is not a duplicate content penalty. when google finds duplicate content they simply filter out the extra copies.

if you add noindex to a preexisting page then google will delist it once it revisits the page.

if you add massive amounts of noindex tags to a site you can potentially hurt the rankings by taking away internal links and unique content ranking for long tail keywords. if you are careful which pages you add noindex to then you should be ok.

If the page is noindex only, without an accompanying nofollow tag, then I think the links on the page are still followed and still pass PR to the pages they link to.

there really is not a duplicate content penalty

Depends on your point of view. When Google finds a duplicate copy, they sometimes replace the original with the new copy. This can happen with pages within a site or on a different site.

Better safe than sorry. Go for the noindex tag. Google should just remove it.

Be careful though. If you noindex a page Google already has in it's index, you won't get that page back in when you remove the noindex tag. Put the noindex tag on an entire site whilst it was down for maintenance/overhaul/redesign. Was down for 4-5 days, been back up for six months without the noindex tag and Google will not re-index it.

If the page is noindex only, without an accompanying nofollow tag, then I think the links on the page are still followed...

That's what is supposed to happen and it did happen, historically. Recently some people have been running new tests that seem to show it's not always true.

So I would recommend explicitly including the "follow" attribute content="noindex,follow". Do that much at least. I am a nit cautious these days with any noindex directives. Google has become pretty good at focusing on the best pages and doing a kind of internal "noindex". At this point, they seem to need less of a helping hand from the webmaster - so I let them do their own thing, and only noindex pages that REALLY don't belong in the search results.

Bottom line for me - duplicate content filtering seems to be a minor thing compared to the issues that using noindex seems to bring up. So I definitely avoid having duplicate URLs as much as possible, but I prefer to let Google choose to filter out those few that slip through my net.

internetheaven said:
Be careful though. If you noindex a page Google already has in it's index, you won't get that page back in when you remove the noindex tag

Are you sure about this? I recently noindexed a page because I'm making some major revisions to it. I had no idea that it won't be re-indexed when I remove the noindex tag. What possible logic is Google following if they don't allow us to temporarily noindex a page?

I was wondering the same thing...

I've often noindexed pages and then removed the tag to allow them to be indexed without issue in the past, so this would be something new if that's really the reason for it not being indexed.

It's not a planned for procedure at Google - it's just something that some people have reported. And there have been enough of those reports to take it into consideration before you place a noindex on a page. What "should" happen isn't always what does happen.

Whether the reported complications came from the site itself, or from something sub-standard at Google, there can be complications.

internetheaven said:
Be careful though. If you noindex a page Google already has in it's index, you won't get that page back in when you remove the noindex tag

aristotle: Are you sure about this?

TheMadScientist: I've often noindexed pages and then removed the tag to allow them to be indexed without issue in the past

I apologise for my definitive language regarding pages being noindexed then losing their spots altogether. I've seen this with 'several' sites/pages - not every site/page. It is something that has been reported and I think it is important to take in to consideration. Just like every other Google issue that affects a small percentage of sites. It's a small thing till it happens to you. ;)

tedster: It's not a planned for procedure at Google - it's just something that some people have reported.

I thought it was something to do with a cross-over between Google's removal tool i.e. the one that says if you drop a page from the index, it could be 90 days before it is re-included. I theorised that Googlebot coming across a noindex tag on a previously indexable page might be treated the same way. Sadly, have been waiting over 90 days and have obtained 500+ more inbound links in that time for one site ... still not re-indexed.

I apologise for my definitive language regarding pages being noindexed then losing their spots altogether.

NP.

Was actually wondering because I've been building a site with a login form on the home page which was noindexed while it was under construction because the site uses mod_rewrite extensively. Moving the mod_rewrite adds one more possible 'oops' if I build it somewhere else, then move and check all the rewriting going on, so I blocked entry and noindexed it since I didn't want bots getting to it before it was ready to go and I was hoping it wasn't some new goofiness to deal with...

I should know in a few days if it's going to be an issue for this particular site or not.

Whether the reported complications came from the site itself, or from something sub-standard at Google, there can be complications.

My guess is the site/page itself...

Recently removed the noindex tag from one home page and it was included within 3 days, removed it from another and it has not been included after a week... It's a 'page specific thing' IMO and my guess is the noindex is not as much of the issue as the changes made while the page was noindexed.

Previously noindexed pages can be reindexed without any issues, it does not reduce the crawl rate, popularity or authority of that page.

That said, if its a page with little or no content, or no original content then noindex it, otherwise let google index and canonicalize similar pages found on either the same site or elsewhere and filter them as they see fit.

It will not be index in future.

The page (home) I had noindexed on the site that was not included is now indexed... My guess is pages having issues with not being re-indexed after noindexing have an issue on / with the page itself and this is not a 'Google Glitch' ... My Opinion from recent experience.