How NOT to Deal with Adblocking Lists: Behind the Scenes Update
Our recent post on adblocking lists has led to some questions from publishers about how countermeasures to combat adblocking, such as native advertising, domain name rotation, and adblock walls, are affected by this underlying system of filters and exceptions.
Many filters have been designed to block obvious advertising elements from being loaded from third-party advertising servers, and this has led some publishers to mistakenly believe that native advertising offers a way to defeat the adblockers. However, adblockers can easily remove or hide any element on a webpage, even if its nature as an ad is concealed as normal content. Rules can be crafted to target elements of a webpage based on size, position, or just about any aspect of HTML and CSS. The makers of Adblock Plus have long been confident about their ability to block native ads, undermining claims that they could save the online advertising industry. Besides the technical challenges, there are other good reasons to rethink relying on native advertising.
The Old Switcheroo
Domain name rotation is another tactic sometimes used to obfuscate the source of both native and regular advertising content, with some ad rotation networks claiming that they can defeat 90% of adblockers. Basically, instead of serving ads from a stable third-party server called, e.g., adserver.com, the advertiser uses an ever-changing rotation of domain names, so that ads could come from, e.g., nv3k9ynphl8qd83.com one minute and 91ir3c4cw9z9hn8.net the next. This sounds promising when you think about the fact that lists such as EasyList are maintained by a community of mostly unpaid ad dodgers. In theory, domains could – especially as the cost of registering some domains is now relatively cheap – be rotated so quickly and intensively as to overwhelm list authors and prevent list servers from keeping pace with the necessary rule subscription updates.
So what about adblock walls? The IAB is currently recommending denial of access to content and publishers in both the US and across Europe are rushing to barricade their content behind adblock walls. But adblockers have been efficiently dealing with these for some time. EasyList has a longstanding policy that an anti-adblock measure can be circumvented if it “limits website functionality or causes significant disruption to browsing” and many adblock walls can be defeated with just a couple of extra filters. Although in some cases the adblockers are successfully encouraged not to automatically add these rules, other adblocking software is not always so reluctant to get involved.
It is technically possible to engage with adblockers in this kind of arms race, but there are drawbacks.
Adblock walls mainly depend on detecting the presence of adblocking software by planting “bait” elements on the page that trigger adblocking filters. In response to this tactic, adblocking software will usually try to evade detection by whitelisting bait elements, leading to a game of cat and mouse. As a result, the only way to reliably detect adblocking software that is actively evading detection is to check if the actual ads actually loaded. For most sites this is problematic because ads usually reside in iframes that the browser security model protects from direct examination. In any case, this approach also requires waiting until all ads have fully loaded before displaying the page – an unacceptable delay on the modern Internet that will probably lead to most users disappearing off into the horizon.
But perhaps the most compelling argument against turning away adblockers with an adblock wall is that adblockers represent an invaluable marketing opportunity and blocking them is probably going to lead to their swift exit to somewhere else.
While a determined combination of some or all of the above countermeasures could potentially stifle list-based adblocking, the cost – in terms of technical expense or loss of visitors due to speed issues – is too great for most sites to accept. So tread carefully if you’re thinking of investing in an adblock wall, rotating domains or embracing native ads.
To learn more, read about PageFair’s approach to advertising beyond blocking.