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
-
E-Commerce Site Collection Pages Not Being Indexed
Hello Everyone, So this is not really my strong suit but I’m going to do my best to explain the full scope of the issue and really hope someone has any insight. We have an e-commerce client (can't really share the domain) that uses Shopify; they have a large number of products categorized by Collections. The issue is when we do a site:search of our Collection Pages (site:Domain.com/Collections/) they don’t seem to be indexed. Also, not sure if it’s relevant but we also recently did an over-hall of our design. Because we haven’t been able to identify the issue here’s everything we know/have done so far: Moz Crawl Check and the Collection Pages came up. Checked Organic Landing Page Analytics (source/medium: Google) and the pages are getting traffic. Submitted the pages to Google Search Console. The URLs are listed on the sitemap.xml but when we tried to submit the Collections sitemap.xml to Google Search Console 99 were submitted but nothing came back as being indexed (like our other pages and products). We tested the URL in GSC’s robots.txt tester and it came up as being “allowed” but just in case below is the language used in our robots:
Intermediate & Advanced SEO | | Ben-R
User-agent: *
Disallow: /admin
Disallow: /cart
Disallow: /orders
Disallow: /checkout
Disallow: /9545580/checkouts
Disallow: /carts
Disallow: /account
Disallow: /collections/+
Disallow: /collections/%2B
Disallow: /collections/%2b
Disallow: /blogs/+
Disallow: /blogs/%2B
Disallow: /blogs/%2b
Disallow: /design_theme_id
Disallow: /preview_theme_id
Disallow: /preview_script_id
Disallow: /apple-app-site-association
Sitemap: https://domain.com/sitemap.xml A Google Cache:Search currently shows a collections/all page we have up that lists all of our products. Please let us know if there’s any other details we could provide that might help. Any insight or suggestions would be very much appreciated. Looking forward to hearing all of your thoughts! Thank you in advance. Best,0 -
Should I use noindex or robots to remove pages from the Google index?
I have a Magento site and just realized we have about 800 review pages indexed. The /review directory is disallowed in robots.txt but the pages are still indexed. From my understanding robots means it will not crawl the pages BUT if the pages are still indexed if they are linked from somewhere else. I can add the noindex tag to the review pages but they wont be crawled. https://www.seroundtable.com/google-do-not-use-noindex-in-robots-txt-20873.html Should I remove the robots.txt and add the noindex? Or just add the noindex to what I already have?
Intermediate & Advanced SEO | | Tylerj0 -
Can noindexed pages accrue page authority?
My company's site has a large set of pages (tens of thousands) that have very thin or no content. They typically target a single low-competition keyword (and typically rank very well), but the pages have a very high bounce rate and are definitely hurting our domain's overall rankings via Panda (quality ranking). I'm planning on recommending we noindexed these pages temporarily, and reindex each page as resources are able to fill in content. My question is whether an individual page will be able to accrue any page authority for that target term while noindexed. We DO want to rank for all those terms, just not until we have the content to back it up. However, we're in a pretty competitive space up against domains that have been around a lot longer and have higher domain authorities. Like I said, these pages rank well right now, even with thin content. The worry is if we noindex them while we slowly build out content, will our competitors get the edge on those terms (with their subpar but continually available content)? Do you think Google will give us any credit for having had the page all along, just not always indexed?
Intermediate & Advanced SEO | | THandorf0 -
Do I need to re-index the page after editing URL?
Hi, I had to edit some of the URLs. But, google is still showing my old URL in search results for certain keywords, which ofc get 404. By crawling with ScremingFrog it gets me 301 'page not found' and still giving old URLs. Why is that? And do I need to re-index pages with new URLs? Is 'fetch as Google' enough to do that or any other advice? Thanks a lot, hope the topic will help to someone else too. Dusan
Intermediate & Advanced SEO | | Chemometec0 -
Pages are Indexed but not Cached by Google. Why?
Here's an example: I get a 404 error for this: http://webcache.googleusercontent.com/search?q=cache:http://www.qjamba.com/restaurants-coupons/ferguson/mo/all But a search for qjamba restaurant coupons gives a clear result as does this: site:http://www.qjamba.com/restaurants-coupons/ferguson/mo/all What is going on? How can this page be indexed but not in the Google cache? I should make clear that the page is not showing up with any kind of error in webmaster tools, and Google has been crawling pages just fine. This particular page was fetched by Google yesterday with no problems, and even crawled again twice today by Google Yet, no cache.
Intermediate & Advanced SEO | | friendoffood2 -
Links from non-indexed pages
Whilst looking for link opportunities, I have noticed that the website has a few profiles from suppliers or accredited organisations. However, a search form is required to access these pages and when I type cache:"webpage.com" the page is showing up as non-indexed. These are good websites, not spammy directory sites, but is it worth trying to get Google to index the pages? If so, what is the best method to use?
Intermediate & Advanced SEO | | maxweb0 -
How do you de-index and prevent indexation of a whole domain?
I have parts of an online portal displaying in SERPs which it definitely shouldn't be. It's due to thoughtless developers but I need to have the whole portal's domain de-indexed and prevented from future indexing. I'm not too tech savvy but how is this achieved? No index? Robots? thanks
Intermediate & Advanced SEO | | Martin_S0 -
Should you stop indexing of short lived pages?
In my site there will be a lot of pages that have a short life span of about a week as they are items on sale, should I nofollow the links meaning the site has a fwe hundred pages or allow indexing and have thousands but then have lots of links to pages that do not exist. I would of course if allowing indexing make sure the page links does not error and sends them to a similarly relevant page but which is best for me with the SEarch Engines? I would like to have the option of loads of links with pages of loads of content but not if it is detrimental Thanks
Intermediate & Advanced SEO | | barney30120