Skip to content
    Moz logo Menu open Menu close
    • Products
      • Moz Pro
      • Moz Pro Home
      • Moz Local
      • Moz Local Home
      • STAT
      • Moz API
      • Moz API Home
      • Compare SEO Products
      • Moz Data
    • Free SEO Tools
      • Domain Analysis
      • Keyword Explorer
      • Link Explorer
      • Competitive Research
      • MozBar
      • More Free SEO Tools
    • Learn SEO
      • Beginner's Guide to SEO
      • SEO Learning Center
      • Moz Academy
      • MozCon
      • Webinars, Whitepapers, & Guides
    • Blog
    • Why Moz
      • Digital Marketers
      • Agency Solutions
      • Enterprise Solutions
      • Small Business Solutions
      • The Moz Story
      • New Releases
    • Log in
    • Log out
    • Products
      • Moz Pro

        Your all-in-one suite of SEO essentials.

      • Moz Local

        Raise your local SEO visibility with complete local SEO management.

      • STAT

        SERP tracking and analytics for enterprise SEO experts.

      • Moz API

        Power your SEO with our index of over 44 trillion links.

      • Compare SEO Products

        See which Moz SEO solution best meets your business needs.

      • Moz Data

        Power your SEO strategy & AI models with custom data solutions.

      NEW Keyword Suggestions by Topic
      Moz Pro

      NEW Keyword Suggestions by Topic

      Learn more
    • Free SEO Tools
      • Domain Analysis

        Get top competitive SEO metrics like DA, top pages and more.

      • Keyword Explorer

        Find traffic-driving keywords with our 1.25 billion+ keyword index.

      • Link Explorer

        Explore over 40 trillion links for powerful backlink data.

      • Competitive Research

        Uncover valuable insights on your organic search competitors.

      • MozBar

        See top SEO metrics for free as you browse the web.

      • More Free SEO Tools

        Explore all the free SEO tools Moz has to offer.

      NEW Keyword Suggestions by Topic
      Moz Pro

      NEW Keyword Suggestions by Topic

      Learn more
    • Learn SEO
      • Beginner's Guide to SEO

        The #1 most popular introduction to SEO, trusted by millions.

      • SEO Learning Center

        Broaden your knowledge with SEO resources for all skill levels.

      • On-Demand Webinars

        Learn modern SEO best practices from industry experts.

      • How-To Guides

        Step-by-step guides to search success from the authority on SEO.

      • Moz Academy

        Upskill and get certified with on-demand courses & certifications.

      • MozCon

        Save on Early Bird tickets and join us in London or New York City

      Unlock flexible pricing & new endpoints
      Moz API

      Unlock flexible pricing & new endpoints

      Find your plan
    • Blog
    • Why Moz
      • Digital Marketers

        Simplify SEO tasks to save time and grow your traffic.

      • Small Business Solutions

        Uncover insights to make smarter marketing decisions in less time.

      • Agency Solutions

        Earn & keep valuable clients with unparalleled data & insights.

      • Enterprise Solutions

        Gain a competitive edge in the ever-changing world of search.

      • The Moz Story

        Moz was the first & remains the most trusted SEO company.

      • New Releases

        Get the scoop on the latest and greatest from Moz.

      Surface actionable competitive intel
      New Feature

      Surface actionable competitive intel

      Learn More
    • Log in
      • Moz Pro
      • Moz Local
      • Moz Local Dashboard
      • Moz API
      • Moz API Dashboard
      • Moz Academy
    • Avatar
      • Moz Home
      • Notifications
      • Account & Billing
      • Manage Users
      • Community Profile
      • My Q&A
      • My Videos
      • Log Out

    The Moz Q&A Forum

    • Forum
    • Questions
    • Users
    • Ask the Community

    Welcome to the Q&A Forum

    Browse the forum for helpful insights and fresh discussions about all things SEO.

    1. Home
    2. SEO Tactics
    3. Intermediate & Advanced SEO
    4. Pitfalls when implementing the “VARY User-Agent” server response

    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.

    Pitfalls when implementing the “VARY User-Agent” server response

    Intermediate & Advanced SEO
    2
    2
    791
    Loading More Posts
    • Oldest to Newest
    • Newest to Oldest
    • Most Votes
    Reply
    • Reply as question
    Log in to reply
    This topic has been deleted. Only users with question management privileges can see it.
    • linklater
      linklater last edited by

      We serve up different desktop/mobile optimized html on the same URL, based on a visitor’s device type.

      While Google continue to recommend the HTTP Vary: User-Agent header for mobile specific versions of the page (http://www.youtube.com/watch?v=va6qtaiZRHg), we’re also aware of issues raised around CDN caching; http://searchengineland.com/mobile-site-configuration-the-varies-header-for-enterprise-seo-163004  / http://searchenginewatch.com/article/2249533/How-Googles-Mobile-Best-Practices-Can-Slow-Your-Site-Down  /  http://orcaman.blogspot.com/2013/08/cdn-caching-problems-vary-user-agent.html

      As this is primarily for Google's benefit, it's been proposed that we only returning the Vary: User-Agent header when a Google user agent is detected (Googlebot/MobileBot/AdBot).

      So here's the thing: as the server header response is not “content” per se I think this could be an okay solution, though wanted to throw it out there to the esteemed Moz community and get some additional feedback.

      You guys see any issues/problems with implementing this solution?

      Cheers!

      linklater

      1 Reply Last reply Reply Quote 0
      • Tom-Anthony
        Tom-Anthony last edited by

        So, there are lots of 'ifs' here, but the primary problem I see with your plan is that the CDN will return the content to Googlebot without the request hitting your server so you won't have the option to serve different headers to Googlebot.

        Remember that every page is the main HTML content (which may be static or dynamically generated for every request), and then a whole bunch of other resources (Javascript and CSS files, images, font files etc.). These other resources are typically static and lend themselves far better to being cached.

        Are your pages static or dynamic? If they are dynamic then you are possibly not benefitting from them being cached anyway, so you could use the 'vary' header on just these pages, and not on any static resources. This would ensure your static resources are cached by your CDN and give you a lot of the benefit of the CDN, and only the dynamic HTML content is served directly from the server.

        If most of your pages are static you could still use this approach, but just without the full benefit of the CDN, which sucks.

        Some of the CDNs are already working on this (see http://www.computerworld.com/s/article/9225343/Akamai_eyes_acceleration_boost_for_mobile_content and http://orcaman.blogspot.co.uk/2013/08/cdn-caching-problems-vary-user-agent.html) to try and find better solutions.

        I hope some of this helps! 🙂

        1 Reply Last reply Reply Quote 1
        • 1 / 1
        • First post
          Last post

        Got a burning SEO question?

        Subscribe to Moz Pro to gain full access to Q&A, answer questions, and ask your own.


        Start my free trial


        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.

        • See all categories

        Related Questions

        • AdenaSEO

          Server update to ipv6, SEO consequences

          Hi all, I read the article from 2014 on MOZ regarding ipv6.
          https://moz.com/blog/ipv6-cblocks-and-seo Our technical department is about to change our server from ipv4 to ipv6.
          Are there any things we have to consider regarding SEO / rankings / duplicate content etc.. with this transition? I hope you have a little spare time to answer this question. Regards,
          Tom

          Intermediate & Advanced SEO | | AdenaSEO
          1
        • jaynamarino

          How To Implement Breadcrumbs

          Hi, I'm looking to implement breadcrumbs for e-commerce store so they will appear in the SERP results like the attached image. In terms of implementing to a site, would you simply add HTML to each page like this Google example? Which looks like this: Books › Science Fiction Award Winners Then is there anything you need to do, to get this showing in the SERPs results e.g. doing something in search console. Or do you just wait into google has crawled and hopefully starts showing in the SERPs results? Cheers. wn3ybMMOQFW98fNQkxtJkA.png [SERP results with bread crumbs](SERP results with bread crumbs)

          Intermediate & Advanced SEO | | jaynamarino
          0
        • jacob.young.cricut

          Will I lose Link Juice when implementing a Reverse Proxy?

          My company is looking at consolidating 5 websites that it has running on magento, wordpress, drupal and a few other platforms on to the same domain. Currently they're all on subdomains but we'd like to consolidate the subdomains to folders for UX and SEO potential. Currently they look like this: shop.example.com blog.example.com uk.example.com us.example.com After the reverse proxy they'll look like this: example.com/uk/ example.com/us/ example.com/us/shop example.com/us/blog I'm curious to know how much link juice will be lost in this switch. I've read a lot about site migration (especially the Moz example). A lot of these guides/case studies just mention using a bunch of 301's but it seems they'd probably be using reveres proxies as well. My questions are: Is a reverse proxy equal to or worse/better than a 301? Should I combine reverse proxy with a 301 or rel canonical tag? When implementing a reverse proxy will I lose link juice = ranking? Thanks so much! Jacob

          Intermediate & Advanced SEO | | jacob.young.cricut
          0
        • accpar

          Fast/Easy Way to Implement Canonical tags in Bulk in Magento CMS?

          Hello Amazing SEO Community! Quick Q for a client with a TON of duplicate content. (yikes!) My client is currently undertaking a large SEO project around canonical tagging for their thousands of duplicate pages. Currently, one product sits on multiple URLs and they are being indexed as different pages (with the same content). The issue is found across all products and other pages, and across their international sites as well. One core challenge they face now is lack of time/resources from their developer side. The solution we see to the duplicate content is to manually add a canonical tag to each of our tens of thousands of pages. Their content management system is Magento. Has anyone ever tackled canonicalization for a large site that uses Magento? Any more efficient solutions to manual tagging is ideal. Thanks in advance for your input. -Bonnie

          Intermediate & Advanced SEO | | accpar
          0
        • RG_SEO

          Best server-side sitemap generators

          I've been looking into sitemap generators recently and have got a good knowledge of what creating a sitemap for a small website of below 500 URLs involves. I have successfully generated a sitemap for a very small site, but I’m trying to work out the best way of crawling a large site with millions of URLs. I’ve decided that the best way to crawl such a large number of URLs is to use a server side sitemap, but this is an area that doesn’t seem to be covered in detail on SEO blogs / forums. Could anyone recommend a good server side sitemap generator? What do you think of the automated offerings from Google and Bing? I’ve found a list of server side sitemap generators from Google, but I can’t see any way to choose between them. I realise that a lot will depend on the type of technologies we use server side, but I'm afraid that I don't know them at this time.

          Intermediate & Advanced SEO | | RG_SEO
          0
        • EcommerceSite

          Why is my servers ip address showing up in Webmaster Tools?

          In links to my site in Google Webmaster Tools I am showing over 28,000 links from an ip address. The ip address is the address that my server is hosted on. For example it shows 200.100.100.100/help, almost like there are two copies of my site, one under the domain name and one under the ip address. Is this bad? Or is it just showing up there and Google knows that it is the same since the ip and domain are from the same server?

          Intermediate & Advanced SEO | | EcommerceSite
          0
        • esiow2013

          Should I run 302 first before implementing 301?

          I just want to ask if it is necessary to run 302 redirections first before redirecting old to new URLs permanently. I heard that we should run temporary redirects first so we can check after and to avoid passing the link juice but I want to hear thoughts from experts. Do i need to test 302s for old pages that are still live or should we redirect old URLs once these pages already removed from the site?

          Intermediate & Advanced SEO | | esiow2013
          0
        • Thos003

          Server Migration, Does it effect SEO?

          About to go through a server migration. My intitial thought is that a change in servers shouldn't really change my rankings. But I've heard rumors... Can a server migration change rankings? Why?

          Intermediate & Advanced SEO | | Thos003
          0

        Get started with Moz Pro!

        Unlock the power of advanced SEO tools and data-driven insights.

        Start my free trial
        Products
        • Moz Pro
        • Moz Local
        • Moz API
        • Moz Data
        • STAT
        • Product Updates
        Moz Solutions
        • SMB Solutions
        • Agency Solutions
        • Enterprise Solutions
        Free SEO Tools
        • Domain Authority Checker
        • Link Explorer
        • Keyword Explorer
        • Competitive Research
        • Brand Authority Checker
        • Local Citation Checker
        • MozBar Extension
        • MozCast
        Resources
        • Blog
        • SEO Learning Center
        • Help Hub
        • Beginner's Guide to SEO
        • How-to Guides
        • Moz Academy
        • API Docs
        About Moz
        • About
        • Team
        • Careers
        • Contact
        Why Moz
        • Case Studies
        • Testimonials
        Get Involved
        • Become an Affiliate
        • MozCon
        • Webinars
        • Practical Marketer Series
        • MozPod
        Connect with us

        Contact the Help team

        Join our newsletter
        Moz logo
        © 2021 - 2025 SEOMoz, Inc., a Ziff Davis company. All rights reserved. Moz is a registered trademark of SEOMoz, Inc.
        • Accessibility
        • Terms of Use
        • Privacy

        Looks like your connection to Moz was lost, please wait while we try to reconnect.