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
-
Will it be possible to point diff sitemap to same robots.txt file.
Will it be possible to point diff sitemap to same robots.txt file.
Technical SEO | | nlogix
Please advice.0 -
Robots.txt on refinements
In dealing with Panda do you think it is a good idea to put all refinements for category pages in the robots.txt file? We already have a lot as noindex, follow but I am wondering if it would be better to address from a crawl perspective as the pages are probably thin duplicate content to Google.
Technical SEO | | Gordian0 -
Canonical URL
Hi there Our website www.snowbusiness.com has a non www version and this one has 398 backlinks. What is the best way of transfering this link value if i establish the www. address as the canonical URL? Thanks, Ben
Technical SEO | | SnowFX0 -
The use of robots.txt
Could someone please confirm that if I do not want to block any pages from my URL, then I do not need a robots.txt file on my site? Thanks
Technical SEO | | ICON_Malta0 -
No indexing url including query string with Robots txt
Dear all, how can I block url/pages with query strings like page.html?dir=asc&order=name with robots txt? Thanks!
Technical SEO | | HMK-NL0 -
Robots txt
We have a development site that we want google and other bots to stay out of but we want roger to have access. Currently our robots.txt looks like this: User-agent: *
Technical SEO | | LadyApollo
Disallow: /cgi-bin/
Disallow: /development/ What would i need to addd or change to let him through? Thank you.0 -
Should i use NoIndex, Follow & Rel=Canonical Tag In One Page?
I am having pagination problem with one of my clients site , So I am deciding to use noindex, follow tag for the Page 2,3,4 etc for not to have duplicated content issue, Because obviously SEOMoz Crawl Diagnostics showing me lot of duplicate page contents. And past 2 days i was in constant battle whether to use noindex, follow tag or rel=canonical tag for the Page 2,3,4 and after going through all the Q&A,None of them gives me crystal clear answer. So i thought "Why can't i use 2 of them together in one page"? Because I think (correct me if i am wrong) 1.noindex, follow is old and traditional way to battle with dup contents
Technical SEO | | DigitalJungle
2.rel=canonical is new way to battle with dup contents Reason to use 2 of them together is: Bot finds to the non-canonical page first and looks at the tag nofollow,index and he knows not to index that page,meantime he finds out that canonical url is something something according to the url given in the tag,NO? Help Please???0 -
Should I set up a disallow in the robots.txt for catalog search results?
When the crawl diagnostics came back for my site its showing around 3,000 pages of duplicate content. Almost all of them are of the catalog search results page. I also did a site search on Google and they have most of the results pages in their index too. I think I should just disallow the bots in the /catalogsearch/ sub folder, but I'm not sure if this will have any negative effect?
Technical SEO | | JordanJudson0