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 -
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 -
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 -
Isnt it better to have headlines in H1 and H2 tags instead of p tags?
I am working with a simple site http://http://lightsigns.com/Uniko_Manufacturing_Limited.html They seek more SEO traffic. However, the two big headlines that read "Wholesale Supply to the Sign and Display Industries" which is on line 241 and 242 of the source code, its in a p tag, i.e. <p <span class="webkit-html-tag">style</p <span>="padding-top: 0pt; " class="paragraph_style_1">Wholesale Supply to the and <p <span class="webkit-html-tag">style</p <span>="padding-bottom: 0pt; " class="paragraph_style_1">Sign and Display Industries Likewise, the product titles are in p tags, also. For example, on the Slide-in Light Box product page, http://lightsigns.com/Slide_In_light_box.html , I have done keyword research and no one is using the words slide in light box.Plus, it is also a p tag, ie. line 43 reads style="padding-bottom: 0pt; padding-top: 0pt; " class="paragraph_style">Slide-in Light Box If I suggest that they make an H2 tag with SEO-optimized keywords such as Display Light Box - Slide-In LIght Box, would this indeed help SEO? In summary, is it correct to say that H1 and H2 tags are stronger signals to the search bots of what the page is about?
Technical SEO | | BridgetGibbons1 -
Will an XML sitemap override a robots.txt
I have a client that has a robots.txt file that is blocking an entire subdomain, entirely by accident. Their original solution, not realizing the robots.txt error, was to submit an xml sitemap to get their pages indexed. I did not think this tactic would work, as the robots.txt would take precedent over the xmls sitemap. But it worked... I have no explanation as to how or why. Does anyone have an answer to this? or any experience with a website that has had a clear Disallow: / for months , that somehow has pages in the index?
Technical SEO | | KCBackofen0 -
Geotargeting duplicate content to different regions - href and canonical tag confusion
If you duplicate content onto a sub-folder for say a new US geotargeted site (to target kw spelling differences) and, in addition to GWT geotargeting settings, implement the 'Canonical' and 'Hreflang' tags on these new pages to show G different region and language version (en-us). Then does the original/main site similar pages also need to have canonical and href tags ? The main/original sites page I don't really want to target a specific country (although existing signals (hosting etc) will be UK (primary target of main site) but pages show up in other country searches too (which we want). Im presuming fine to leave the original/main site as it currently is although wording in google blog/webmaster central articles etc are a bit confusing hence why im asking for anyone elses opinion/input on this. Also is there are any benefit (or just best practice) to use 'www.example.com/en-us/...' in the subdirectory URL as opposed to just 'www.example.com/us/' many thanks in advance to any commentators 🙂
Technical SEO | | Dan-Lawrence0 -
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 -
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