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:
Got a burning SEO question?
Subscribe to Moz Pro to gain full access to Q&A, answer questions, and ask your own.
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
-
Canonical or hreflang?
I have four English sites for four different countries, UK, Ireland, Australia and New Zealand and I want to share some content between the sites. On the pages that share the content, which is essentially exactly the same on all 4 sites, do I use the hreflang tags like: or do I add a canonical tag to the other three pointing to the "origin", which would be the UK site? I believe it is best practice to use one or the other, but I'm not sure which make sense in this situation.
Technical SEO | | andrew-mso0 -
Canonical Tag when using Ajax and PhantomJS
Hello, We have a site that is built using an AJAX application. We include the meta fragment tag in order to get a rendered page from PhantomJS. The URL that is rendered to google from PhantomJS then is www.oursite.com/?escaped_fragment= In the SERP google of course doesnt include the hashtag in the URL. So my question, with this setup, do i still need a canonical tag and if i do, would the canonical tag be the escaped fragment URL or the regular URL? Much Appreciated!
Technical SEO | | RevanaDigitalSEO0 -
How do I fix the h1 tag?
No More Than One H1 Tag Easy fix <dl> <dt>Number of H1s</dt> <dd>2</dd> <dt>Explanation</dt> <dd>Best practices for both SEO and accessibility require only a single H1 tag. The H1 is meant to be the page's headline, and thus, multiple H1s are confusing. Consider employing H2, H3 or CSS styles to achieve the same results with text visualization.</dd> <dt>Recommendation</dt> <dd>Remove multiple instances of the H1 tag, so that only one exists on the page.</dd> <dd>I get this error yet it does not tell me how to fix it. I'm not even sure what the H1 tag is?
Technical SEO | | 678648631264
</dd> </dl>0 -
Allow or Disallow First in Robots.txt
If I want to override a Disallow directive in robots.txt with an Allow command, do I have the Allow command before or after the Disallow command? example: Allow: /models/ford///page* Disallow: /models////page
Technical SEO | | irvingw0 -
Do I need to add canonical link tags to pages that I promote & track w/ UTM tags?
New to SEOmoz, loving it so far. I promote content on my site a lot and am diligent about using UTM tags to track conversions & attribute data properly. I was reading earlier about the use of link rel=canonical in the case of duplicate page content and can't find a conclusive answer whether or not I need to add the canonical tag to these pages. Do I need the canonical tag in this case? If so, can the canonical tag live in the HEAD section of the original / base page itself as well as any other URLs that call that content (that have UTM tags, etc)? Thank you.
Technical SEO | | askotzko1 -
Can I Disallow Faceted Nav URLs - Robots.txt
I have been disallowing /*? So I know that works without affecting crawling. I am wondering if I can disallow the faceted nav urls. So disallow: /category.html/? /category2.html/? /category3.html/*? To prevent the price faceted url from being cached: /category.html?price=1%2C1000
Technical SEO | | tylerfraser
and
/category.html?price=1%2C1000&product_material=88 Thanks!0 -
Google Off/On Tags
I came across this article about telling google not to crawl a portion of a webpage, but I never hear anyone in the SEO community talk about them. http://perishablepress.com/press/2009/08/23/tell-google-to-not-index-certain-parts-of-your-page/ Does anyone use these and find them to be effective? If not, how do you suggest noindexing/canonicalizing a portion of a page to avoid duplicate content that shows up on multiple pages?
Technical SEO | | Hakkasan1 -
Should there be a canonical tag on my 404 error page?
In my crawl diagnostics, I notice some 4xx client errors. They are appearing for pages that no longer exist, so I'm not sure what the problem is. Shouldn't they just be dealt as 404's? Anyway, on closer inspection I noticed that my 404 error page contains a canonical tag which points to the missing page. Could this be the issue? Is it a good idea to remove the canonical tag from this error page? Thanks.
Technical SEO | | Leighm0