Jackie Long

Why not block ad bots?

Some ad fraud tools focus on blocking bots, but there are several reasons why NS8 does not. We explain our reasoning behind this choice.

Invalid traffic (IVT) poses a problem for most online companies. In particular, IVT can cost businesses a lot of money by using bots to deflate an advertising budget through fraudulent clicks, impressions, and retargeting.

NS8 Protect flags bots that come to a site and prevents them from making it onto a retargeting list, which prevents additional money from being spent on retargeting these bots. But why not prevent all bots from seeing any ads in the first place?


Websites sometimes use a system called caching to make a site run faster. Instead of having to reload a page every time a person asks for it, a server will “cache” the latest version of a site (essentially like a download or saved version) so that it can return data to the viewer faster. Sites do this by having bots run a script to cache the site. If your ads are invisible to bots, they may not appear on the cached version or may appear incomplete or incorrect. When this happens, potential customers can miss necessary parts of your ads or may not see them at all.


Bots that are not malicious will identify themselves to a website. Sites running ads (particularly programmatic ads) generally run on JavaScript, which recognizes this identifier. Any impressions or clicks made by these known bots are already excluded by the JavaScript code and should not produce costs for the advertiser.

It is only malicious bots who fail to identify themselves that generate costs. These bots usually mimic human behavior and are called Sophisticated Invalid Traffic (SIVT). Most ad-blocking software is unable to differentiate SIVT from humans, which means these bots can continue draining your budget without resistance.

While NS8 Protect is capable of differentiating between good bots and bad bots, not knowing that these bots are viewing your ads may mean that you continue to advertise on sites that are mostly bot traffic. This may lead to reputation issues and other problems. You can, however, exclude previously-known bots from future campaigns. This gives you the assurance that you are blocking known bots and helps you weed out sites that serve you bad traffic.

Known Sources

One way to block malicious traffic without impacting valid users is to simply prevent any traffic coming from specific fraudulent sources from viewing your ad. However, these lists are constantly changing (since fraudsters are constantly adapting), so you may be blocking some bad traffic while letting even worse traffic through. In addition, many ad platforms have limits on how many traffic sources you can block. These lists would have to be constantly updated and still would not be entirely effective.

(Note that this is different from blocking individual bots that have already been recognized as fraudulent through NS8 Protect’s Google Ads integrations. Those lists are based on specific users’ data that is recognized as fraud rather than blocking an entire source of traffic.)

IP Rotation

Similarly, some malicious bots have the ability to change attributes at will in order to get through your defenses. While a particular IP address may be a known source of fraud, bots will likely rotate through multiple IP addresses while attempting to view the given ad. They can also change browser strings and other identifying information in an attempt to get the ad served. Even if 80% of these tries are blocked, each bot will likely be served some number of ads. You still lose money to the bot, and you have no way of knowing fraud happened, since this interaction just appears as normal traffic in your analytics.


Which leads to our last point — information can be valuable. By tracking IVT instead of blocking it, NS8 Protect is able to score specific campaigns and individual users to show where invalid traffic is coming from and when it reaches your site. NS8 Protect can even tie fraudulent orders to the specific campaigns from which they originated. Companies get the tools they need to optimize their ad campaigns and reach human users without causing additional problems.

To learn more about NS8’s Google Ad integration or bot blocking technology, check out our technical guides in the NS8 Resource Center.

About the author
Jackie Long

Jackie is a Content Specialist at NS8. With a varied background and over 6 years of content creation experience, Jackie works hard to provide a compelling range of informative articles.

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