Moz Q&A is closed.
After more than 13 years, and tens of thousands of questions, Moz Q&A closed on 12th December 2024. Whilst we’re not completely removing the content - many posts will still be possible to view - we have locked both new posts and new replies. More details here.
Robots.txt and canonical tag
-
In the SEOmoz post - http://www.seomoz.org/blog/robot-access-indexation-restriction-techniques-avoiding-conflicts, it's being said -
If you have a robots.txt disallow in place for a page, the canonical tag will never be seen.
Does it so happen that if a page is disallowed by robots.txt, spiders DO NOT read the html code ?
-
Thanks Ryan for explaining things very clearly.
-
What we know is there have been many cases where a page that is blocked in robots.txt has appeared in search results. The explanation provided is that robots.txt blocks crawlers during normal site visits, but not necessarily on visits where they are following links from other sites.
-
If spiders follow links to an article on my site, will they read the contents then ? If the canonical tag is on article page itself, will canonical tag will be seen ?
-
Daylan offered a great answer but I would like to add one exception. When crawlers from the major SEs visit your site they will honor your robots.txt file but sometimes they will follow links from other sites to an article on your site, and during that particular visit they will not see the robots.txt file and index your page.
This is one of the reasons why your robots.txt file should be used as minimally as possible, and when it is used you should have a backup process in place such as the canonical or noindex tag on a page.
-
Thanks Daylan for your quick response. I just wanted a second opinion that canonical tag will never be seen if a page is disallowed.
-
Thats correct in most cases:
It works likes this: a robot wants to vists a Web site URL, say http://www.example.com/welcome.html. Before it does so, it firsts checks for http://www.example.com/robots.txt, and finds:
User-agent: *
Disallow: /The "User-agent: *" means this section applies to all robots. The "Disallow: /" tells the robot that it should not visit any pages on the site.
Robots can ignore your /robots.txt. Especially malware robots that scan the web for security vulnerabilities, and email address harvesters used by spammers will pay no attention.
More information available here about:
Browse Questions
Explore more categories
-
Moz Tools
Chat with the community about the Moz tools.
-
SEO Tactics
Discuss the SEO process with fellow marketers
-
Community
Discuss industry events, jobs, and news!
-
Digital Marketing
Chat about tactics outside of SEO
-
Research & Trends
Dive into research and trends in the search industry.
-
Support
Connect on product support and feature requests.
Related Questions
-
Robots.txt allows wp-admin/admin-ajax.php
Hello, Mozzers!
Technical SEO | | AndyKubrin
I noticed something peculiar in the robots.txt used by one of my clients: Allow: /wp-admin/admin-ajax.php What would be the purpose of allowing a search engine to crawl this file?
Is it OK? Should I do something about it?
Everything else on /wp-admin/ is disallowed.
Thanks in advance for your help.
-AK:2 -
Is there a limit to how many URLs you can put in a robots.txt file?
We have a site that has way too many urls caused by our crawlable faceted navigation. We are trying to purge 90% of our urls from the indexes. We put no index tags on the url combinations that we do no want indexed anymore, but it is taking google way too long to find the no index tags. Meanwhile we are getting hit with excessive url warnings and have been it by Panda. Would it help speed the process of purging urls if we added the urls to the robots.txt file? Could this cause any issues for us? Could it have the opposite effect and block the crawler from finding the urls, but not purge them from the index? The list could be in excess of 100MM urls.
Technical SEO | | kcb81780 -
Blocked jquery in Robots.txt, Any SEO impact?
I've heard that Google is now indexing links and stuff available in javascript and jquery. My webmastertools is showing that some links are blocked in robots.txt of jquery. Sorry I'm not a developer or designer. I want to know is there any impact of this on my SEO? and also how can I unblock it for the robots? Check this screenshot: http://i.imgur.com/3VDWikC.png
Technical SEO | | hammadrafique0 -
I accidentally blocked Google with Robots.txt. What next?
Last week I uploaded my site and forgot to remove the robots.txt file with this text: User-agent: * Disallow: / I dropped from page 11 on my main keywords to past page 50. I caught it 2-3 days later and have now fixed it. I re-imported my site map with Webmaster Tools and I also did a Fetch as Google through Webmaster Tools. I tweeted out my URL to hopefully get Google to crawl it faster too. Webmaster Tools no longer says that the site is experiencing outages, but when I look at my blocked URLs it still says 249 are blocked. That's actually gone up since I made the fix. In the Google search results, it still no longer has my page title and the description still says "A description for this result is not available because of this site's robots.txt – learn more." How will this affect me long-term? When will I recover my rankings? Is there anything else I can do? Thanks for your input! www.decalsforthewall.com
Technical SEO | | Webmaster1230 -
Two different canonical tags on one page
Due to an error, some of my pages now have two canonical tags on them. One is correct and the other goes to a nonsense URL (404 page). I know I should ideally remove the incorrect ones, but it's a big manual job. Are they doing any harm? Can I just leave them there and let Google figure it out? The correct ones are higher up in the code. Will this make a difference? Any help appreciated.
Technical SEO | | ShearingsGroup0 -
Internal search : rel=canonical vs noindex vs robots.txt
Hi everyone, I have a website with a lot of internal search results pages indexed. I'm not asking if they should be indexed or not, I know they should not according to Google's guidelines. And they make a bunch of duplicated pages so I want to solve this problem. The thing is, if I noindex them, the site is gonna lose a non-negligible chunk of traffic : nearly 13% according to google analytics !!! I thought of blocking them in robots.txt. This solution would not keep them out of the index. But the pages appearing in GG SERPS would then look empty (no title, no description), thus their CTR would plummet and I would lose a bit of traffic too... The last idea I had was to use a rel=canonical tag pointing to the original search page (that is empty, without results), but it would probably have the same effect as noindexing them, wouldn't it ? (never tried so I'm not sure of this) Of course I did some research on the subject, but each of my finding recommanded one of the 3 methods only ! One even recommanded noindex+robots.txt block which is stupid because the noindex would then be useless... Is there somebody who can tell me which option is the best to keep this traffic ? Thanks a million
Technical SEO | | JohannCR0 -
Invisible robots.txt?
So here's a weird one... Client comes to me for some simple changes, turns out there are some major issues with the site, one of which is that none of the correct content pages are showing up in Google, just ancillary (outdated) ones. Looks like an issue because even the main homepage isn't showing up with a "site:domain.com" So, I add to Webmaster Tools and, after an hour or so, I get the red bar of doom, "robots.txt is blocking important pages." I check it out in Webmasters and, sure enough, it's a "User agent: * Disallow /" ACK! But wait... there's no robots.txt to be found on the server. I can go to domain.com/robots.txt and see it but nothing via FTP. I upload a new one and, thankfully, that is now showing but I've never seen that before. Question is: can a robots.txt file be stored in a way that can't be seen? Thanks!
Technical SEO | | joshcanhelp0 -
Robots.txt File Redirects to Home Page
I've been doing some site analysis for a new SEO client and it has been brought to my attention that their robots.txt file redirects to their homepage. I was wondering: Is there a benfit to setup your robots.txt file to do this? Will this effect how their site will get indexed? Thanks for your response! Kyle Site URL: http://www.radisphere.net/
Technical SEO | | kchandler0