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.
How can I prevent duplicate pages being indexed because of load balancer (hosting)?
-
The site that I am optimising has a problem with duplicate pages being indexed as a result of the load balancer (which is required and set up by the hosting company).
The load balancer passes the site through to 2 different URLs:
Some how, Google have indexed 2 of the same URLs (which I was obviously hoping they wouldn't) - the first on www and the second on www2.
The hosting is a mirror image of each other (www and www2), meaning I can't upload a robots.txt to the root of www2.domain.com disallowing all. Also, I can't add a canonical script into the website header of www2.domain.com pointing the individual URLs through to www.domain.com etc.
Any suggestions as to how I can resolve this issue would be greatly appreciated!
-
There are two ways to handle load balancing, and it appears that your hosting company / server company chose to use the DNS round-robin routing option.
According to the Wikipedia page on load balancing:
http://en.wikipedia.org/wiki/Load_balancing_(computing)"Load balancing usually involves dedicated software or hardware, such as a multilayer switch or a Domain Name System server process."
Round Robin DNS Load Balancing: Basically you use the DNS routing system to handle requests. When someone visits your site, 50% of the people are routed to www.domain.com, and 50% are routed to ww1.domain.com. Both sites contain the same identical content; it's the URLs that are slightly different. Sometimes the domains are the same; but you have different IP addresses for www.domain.com.
Advantages: you don't need a dedicated load balancing piece of software or hardware, so it's less expensive.
Disadvantages: this technique exposes the individual web servers to the end user seeing the site. You can also suffer from duplicate content penalties, too. Finally, if you are relying on the round robin DNS system for load balancing, and a DNS server or one of the Web servers goes down, there's not an easy fail-over (as many DNS records are cached).More about Round Robin DNS: http://en.wikipedia.org/wiki/Round-robin_DNS
Hardware / Software Load Balancer:
In this case, your DNS zone file tells the end user to go to one IP address when they type in www.domain.com. The hardware or software load balancer then sees the request, and then hands off the content to one of the web servers in a cluster.Advantages: No duplicate content penalty; to the end user, they just see one web server and not individual sub-domains (www.domain.com and ww1.domain.com). A load balancer can also cache specific items like a CSS page, so the load on the Web server is even more minimal.
Disadvantages: You're introducing another piece of hardware or software (i.e. more cost); this piece could also be a single point of failure into the mix. You need someone to figure out how to set this up and make sure it all works.
More on this type of Load Balancing: http://en.wikipedia.org/wiki/Load_balancing_(computing)#Internet-based_services
Load balancing can get complicated as soon as you have databases involved, but with a good design, multiple front end Web servers can talk to one single backend database server. The goal would be to cache as much content as possible as "static" elements, using caching systems like Varnish, that essentially turn database-driven pages into static, old-school HTML pages. And then only when someone needs to save something from the database (i.e. making a purchase on an eCommerce site), the system then interacts with it.
My recommendation:
(1) Move from the Round Robin Robin DNS to a hardware or software load balancer.(2) If that isn't an easy solution, implement the Round Robin DNS solution to use identical A records for each server.
For example, you might have identical entries in your DNS zone files for both DNS servers:
www.domain.com A 69.94.15.10
NS2.domain.com:
www.domain.com A 75.64.18.12This should at least eliminate your duplicate content issue, but you still do have a few disadvantages (described above). This also could lead to server issues, as the servers might be confused if they are the authoritative ones.
And if both servers are sending email, pay special attention to your SPF record, to make sure that you are allowing both IP addresses to be able to send email. (This is often overlooked.)
Hope this is helpful!
-- Jeff
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
-
Duplicate content in Shopify - subsequent pages in collections
Hello everyone! I hope an expert in this community can help me verify the canonical codes I'll add to our store is correct. Currently, in our Shopify store, the subsequent pages in the collections are not indexed by Google, however the canonical URL on these pages aren't pointing to the main collection page (page 1), e.g. The canonical URL of page 2, page 3 etc are used as canonical URLs instead of the first page of the collections. I have the canonical codes attached below, it would be much appreciated if an expert can urgently verify these codes are good to use and will solve the above issues? Thanks so much for your kind help in advance!! -----------------CODES BELOW--------------- <title><br /> {{ page_title }}{% if current_tags %} – tagged "{{ current_tags | join: ', ' }}"{% endif %}{% if current_page != 1 %} – Page {{ current_page }}{% endif %}{% unless page_title contains shop.name %} – {{ shop.name }}{% endunless %}<br /></title>
Intermediate & Advanced SEO | | ycnetpro101
{% if page_description %} {% endif %} {% if current_page != 1 %} {% else %} {% endif %}
{% if template == 'collection' %}{% if collection %}
{% if current_page == 1 %} {% endif %}
{% if template == 'product' %}{% if product %} {% endif %}
{% if template == 'collection' %}{% if collection %} {% endif %}0 -
Can I tell Google to Ignore Parts of a Page?
Hi all, I was wondering if there was some sort of html trick that I could use to selectively tell a search engine to ignore texts on certain parts of a page. Thanks!
Intermediate & Advanced SEO | | Charles_Murdock
Charles0 -
Better to 301 or de-index 403 pages
Google WMT recently found and called out a large number of old unpublished pages as access denied errors. The pages are tagged "noindex, follow." These old pages are in Google's index. At this point, would it better to 301 all these pages or submit an index removal request or what? Thanks... Darcy
Intermediate & Advanced SEO | | 945010 -
Is Google indexing Mp3 audio and MIDI music files? Can that cause any duplicate problems?
Hello, I own virtualsheetmusic.com website and we have several thousands of media files (Mp3 and MIDI files) that potentially Google can index. If that's the case, I am wondering if that could cause any "duplicate" issues of some sort since many of such media files have exact file names or same meta information inside. Any thoughts about this issue are very welcome! Thank you in advance to anyone.
Intermediate & Advanced SEO | | fablau0 -
Our login pages are being indexed by Google - How do you remove them?
Each of our login pages show up under different subdomains of our website. Currently these are accessible by Google which is a huge competitive advantage for our competitors looking for our client list. We've done a few things to try to rectify the problem: - No index/archive to each login page Robot.txt to all subdomains to block search engines gone into webmaster tools and added the subdomain of one of our bigger clients then requested to remove it from Google (This would be great to do for every subdomain but we have a LOT of clients and it would require tons of backend work to make this happen.) Other than the last option, is there something we can do that will remove subdomains from being viewed from search engines? We know the robots.txt are working since the message on search results say: "A description for this result is not available because of this site's robots.txt – learn more." But we'd like the whole link to disappear.. Any suggestions?
Intermediate & Advanced SEO | | desmond.liang1 -
Best practice for removing indexed internal search pages from Google?
Hi Mozzers I know that it’s best practice to block Google from indexing internal search pages, but what’s best practice when “the damage is done”? I have a project where a substantial part of our visitors and income lands on an internal search page, because Google has indexed them (about 3 %). I would like to block Google from indexing the search pages via the meta noindex,follow tag because: Google Guidelines: “Use robots.txt to prevent crawling of search results pages or other auto-generated pages that don't add much value for users coming from search engines.” http://support.google.com/webmasters/bin/answer.py?hl=en&answer=35769 Bad user experience The search pages are (probably) stealing rankings from our real landing pages Webmaster Notification: “Googlebot found an extremely high number of URLs on your site” with links to our internal search results I want to use the meta tag to keep the link juice flowing. Do you recommend using the robots.txt instead? If yes, why? Should we just go dark on the internal search pages, or how shall we proceed with blocking them? I’m looking forward to your answer! Edit: Google have currently indexed several million of our internal search pages.
Intermediate & Advanced SEO | | HrThomsen0 -
Should pages of old news articles be indexed?
My website published about 3 news articles a day and is set up so that old news articles can be accessed through a "back" button with articles going to page 2 then page 3 then page 4, etc... as new articles push them down. The pages include a link to the article and a short snippet. I was thinking I would want Google to index the first 3 pages of articles, but after that the pages are not worthwhile. Could these pages harm me and should they be noindexed and/or added as a canonical URL to the main news page - or is leaving them as is fine because they are so deep into the site that Google won't see them, but I also won't be penalized for having week content? Thanks for the help!
Intermediate & Advanced SEO | | theLotter0 -
Disallowed Pages Still Showing Up in Google Index. What do we do?
We recently disallowed a wide variety of pages for www.udemy.com which we do not want google indexing (e.g., /tags or /lectures). Basically we don't want to spread our link juice around to all these pages that are never going to rank. We want to keep it focused on our core pages which are for our courses. We've added them as disallows in robots.txt, but after 2-3 weeks google is still showing them in it's index. When we lookup "site: udemy.com", for example, Google currently shows ~650,000 pages indexed... when really it should only be showing ~5,000 pages indexed. As another example, if you search for "site:udemy.com/tag", google shows 129,000 results. We've definitely added "/tag" into our robots.txt properly, so this should not be happening... Google showed be showing 0 results. Any ideas re: how we get Google to pay attention and re-index our site properly?
Intermediate & Advanced SEO | | udemy0
