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
-
Does Google read dynamic canonical tags?
Does Google recognize rel=canonical tag if loaded dynamically via javascript? Here's what we're using to load: <script> //Inject canonical link into page head if (window.location.href.indexOf("/subdirname1") != -1) { canonicalLink = window.location.href.replace("/kapiolani", ""); } if (window.location.href.indexOf("/subdirname2") != -1) { canonicalLink = window.location.href.replace("/straub", ""); } if (window.location.href.indexOf("/subdirname3") != -1) { canonicalLink = window.location.href.replace("/pali-momi", ""); } if (window.location.href.indexOf("/subdirname4") != -1) { canonicalLink = window.location.href.replace("/wilcox", ""); } if (canonicalLink != window.location.href) { var link = document.createElement('link'); link.rel = 'canonical'; link.href = canonicalLink; document.head.appendChild(link); } script>
Technical SEO | | SoulSurfer80 -
Robots.txt on http vs. https
We recently changed our domain from http to https. When a user enters any URL on http, there is an global 301 redirect to the same page on https. I cannot find instructions about what to do with robots.txt. Now that https is the canonical version, should I block the http-Version with robots.txt? Strangely, I cannot find a single ressource about this...
Technical SEO | | zeepartner0 -
Blocking Affiliate Links via robots.txt
Hi, I work with a client who has a large affiliate network pointing to their domain which is a large part of their inbound marketing strategy. All of these links point to a subdomain of affiliates.example.com, which then redirects the links through a 301 redirect to the relevant target page for the link. These links have been showing up in Webmaster Tools as top linking domains and also in the latest downloaded links reports. To follow guidelines and ensure that these links aren't counted by Google for either positive or negative impact on the site, we have added a block on the robots.txt of the affiliates.example.com subdomain, blocking search engines from crawling the full subddomain. The robots.txt file is the following code: User-agent: * Disallow: / We have authenticated the subdomain with Google Webmaster Tools and made certain that Google can reach and read the robots.txt file. We know they are being blocked from reading the affiliates subdomain. However, we added this affiliates subdomain block a few weeks ago to the robots.txt, but links are still showing up in the latest downloads report as first being discovered after we added the block. It's been a few weeks already, and we want to make sure that the block was implemented properly and that these links aren't being used to negatively impact the site. Any suggestions or clarification would be helpful - if the subdomain is being blocked for the search engines, why are the search engines following the links and reporting them in the www.example.com subdomain GWMT account as latest links. And if the block is implemented properly, will the total number of links pointing to our site as reported in the links to your site section be reduced, or does this not have an impact on that figure?From a development standpoint, it's a much easier fix for us to adjust the robots.txt file than to change the affiliate linking connection from a 301 to a 302, which is why we decided to go with this option.Any help you can offer will be greatly appreciated.Thanks,Mark
Technical SEO | | Mark_Ginsberg0 -
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 -
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 -
Tags showing up in Google
Yesterday a user pointed out to me that Tags were being indexed in Google search results and that was not a good idea. I went into my Yoast settings and checked the "nofollow, index" in my Taxanomies, but when checking the source code for no follow, I found nothing. So instead, I went into the robot.txt and disallowed /tag/ Is that ok? or is that a bad idea? The site is The Tech Block for anyone interested in looking.
Technical SEO | | ttb0 -
Robots.txt Sitemap with Relative Path
Hi Everyone, In robots.txt, can the sitemap be indicated with a relative path? I'm trying to roll out a robots file to ~200 websites, and they all have the same relative path for a sitemap but each is hosted on its own domain. Basically I'm trying to avoid needing to create 200 different robots.txt files just to change the domain. If I do need to do that, though, is there an easier way than just trudging through it?
Technical SEO | | MRCSearch0 -
Robots.txt file getting a 500 error - is this a problem?
Hello all! While doing some routine health checks on a few of our client sites, I spotted that a new client of ours - who's website was not designed built by us - is returning a 500 internal server error when I try to look at the robots.txt file. As we don't host / maintain their site, I would have to go through their head office to get this changed, which isn't a problem but I just wanted to check whether this error will actually be having a negative effect on their site / whether there's a benefit to getting this changed? Thanks in advance!
Technical SEO | | themegroup0