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number of domains with ads.txt files

A look at ads.txt adoption, its benefits, and the challenges ahead


The Drum—The introduction of ads.txt by the IAB Tech Lab this year is arguably one of the key breakthroughs to repair trust in digital advertising in 2017, a sector that remains buoyant in terms of growth, but is not without its detractors, especially with the growth of automated trading technologies. The Drum explores its evolution.

A report published today (December 20) by MediaRadar claims that only 20% of the top 3,000 publisher sites have implemented ads.txt, a mechanism introduced to the market to help programmatic media traders identify bad actors in the field.

This works primarily by allowing premium media owners to publicly list authorized resellers of their inventory on ad networks and exchanges by listing them on their ‘ads.txt log files.’ Media buyers can then trawl to discern which online ad exchanges are offering legitimate inventory (see video above).

Upon the conduct of its audit, MediaRadar found that only 20% of sites are currently implementing ads.txt, with chief executive officer Todd Krizelman describing the uptake as “modest”.

“After six months, the largest sites are moving quickly, but only 20% of all publisher sites we track today have taken advantage of ads.text. It’s a reminder of the power of inertia, and the importance to really evangelize the benefits of this new way to stop spend on unauthorized counterfeit ad inventory,” he adds.

The study ads to a chorus of calls encouraging more widespread take-up of the protocol with a recent study jointly conducted by Google and a host of premium publishers, such as Business Insider, Washington Post and Turner, warning that those who failed to do so risk losing up to $3.5m per day due to the activity of fraudsters, equating to $1.27bn a year.

A separate study from Google itself (the findings of which would appear to differ slightly from MediaRadar’s upon first look) highlights the benefit of adoption, claiming that media owners using its DoubleClick Ad Exchange and Ad Sense platforms have benefited from an increase in their average CPM.


Similarly, adtech outfit OpenX has been keen to highlight how adoption of the technology has benefited its media trading partners. OpenX tells how a respected industry study found that more premium publishers had selected its platform as a preferred inventory reseller than any other independent exchange – second only to Google’s DoubleClick for Publishers (DFP) overall – with a host of testimonies from publishers such as Axel Springer representatives.

Speaking in the wake of the findings, Jason Fairchild, OpenX chief revenue officer, emphasized the importance for sell-side adtech players to appear on such files, adding that there would likely be “massive blood letting” among those that fail to make the cut.

Likewise, buy-side adtech outfits such as AppNexus and The Trade Deskhave been quick to publicly align themselves with the ads.txt initiative, with both claiming their buy-side offerings will disable buying from ad networks not listed on media owners whose ads.txt files.

Despite the competing numbers cited in recent studies take-up is on the rise, according to Nick Firzzell, SpotX, senior director brand safety and inventory operations, who adds that the introduction of ads.txt “takes a lot of the guess work out of whom the authorized resellers are and who is not.”

According to his observations, as far back as six week ago as little as 20% of websites that SpotX transacted with had implemented ads.txt, although now that figure is closer to north of 50%.

Frizzell adds: “It’s a little to early to properly assess the the impact of its introduction if you compare it to five years ago, but when you can ask for proof of partnership it’s a big help.”

SpotX has worked in partnership with DoubleVerify to help minimize the impact of fraudulent practices such as domain-spoofing and to weed out suspect ad networks peddling non-human traffic. This was performed by using the verification outfit’s ability to trawl through the ad serving chain to identify known malicious software.

“You find that a non-infected machine looks very different from one with funky software on it,” adds Frizzell. “We’re already starting to see some buyers only agreeing to transact on inventory marked with an ads.txt file.”

Similarly, Andre Sevigny, Microsoft Casual Games Studio, advertising lead, agrees with Frizzell’s assessment as to the (more-or-less) immediate positive impact catalyzed by the introduction of ads.txt.

SpotX and Microsoft examined inventory claiming to be from the software giant’s casual games, and found that up to a dozen outfits were passing off fake traffic as their own, according to Sevigny (which is subsequently cuff-off.

“Some were selling millions of impressions that we were not aware of,” he adds. “This devalues the value of your inventory, as DSPs [demand-side platforms] go back to buyers and and report your inventory as a concern.”

The auditing process, and subsequent cull, is not without its technical challenges, reports Sevigny. For instance, app developers that want to appear compliant with ads.txt protocols now have to develop correlating websites with the ads.txt log files in order to evade being blacklisted by DSPs performing due-diligence for their media buyers.

Although the ends justify the means, according to Sevigny. “By design it’s very simple, but in some cases it can make things a little more complex that it already is,” he adds.

Frizzell claims that the work is far from over, especially as media buyers and sellers look to trade new media formats (other than display ads) using automated trading technologies.

“What the industry needs to do now is come up with more defined definitions on other platforms such as in-app, or connected TV,” he adds.

However, while its impact in recent months is beyond doubt, experts point to the fact that a simple introduction of the code is not without its vulnerabilities, constant vigilance is required.

Danish adtech outfit used its unique adtech stack to expose one of the biggest instances of ad fraud with its high profile exposure of ‘Hyphbot’ gaining acres of coverage in the mainstream press last month.

Speaking earlier with The Drum about the investigation, Jay Stevens, Adform, chief revenue officer, warned that a simple ads.txt implementation is “not a silver bullet.”

He explained: “Let’s say that an SSP [supply-side platform] has a dodgy ad network that they’re using for back-filing, they can essentially spoof the same domain that the premium publisher has appointed the legitimate SSP to represent its inventory in their exchange.”

This demonstrates how publishers need to conduct a thorough audit of their adtech supply chain can lead, and not simply resting on the laurels of ads.txt implementation, in order to stay ahead of fraudsters.

Likewise, Marc Goldberg, chief executive of auditing firm Trust Metrics, raises how one of his company’s recent audits of ads.txt files – freely available by inputting the text ‘/ads.txt’ after a website’s URL – found well known fraudulent players present.

He points to loopholes that are currently being exploited by fraudsters such as fake news peddlers are duping buyers by mimicking legitimate sites by using URLs such as ‘’ (a mock example).

They are then able to evade being blacklisted by DSPs by then exploiting self-reporting loopholes by tagging themselves as satire (while serving ‘fake news’ to all intents and purposes). Such loopholes need to be closed down, according to Goldberg.

Such is the impact of ads.txt since its reintroduction, that some of the biggest names in the advertising sector are beginning to pay attention. Speaking on background, adtech executives claim that no less a personality than Marc Pritchard, Procter & Gamble brand chief and 2017’s ‘transparency zealot’, are fielding phone calls about its efficacy.

Well placed sources also speak to how US Federal Law Authorities are also knocking on doors and inquiring further, what is certain is that 2018 will only see an increase in such scrutiny as the loopholes exploited by fraudsters continue to be exposed.

In the interim, OpenX’s Fairchild sums up how legitimate media buyers and sellers can best protect themselves: “Don’t shop in flea markets, go to well-lit marketplaces.”

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