In comparing two people's incognito results, you have no idea if they hit the same search clusters. Were they in the same room? Same ISP? Same geographical regi

In comparing two people's incognito results, you have no idea if they hit the same search clusters. Were they in the same room? Same ISP? Same geographical region? Same continent? If I issue the same search back to back in different windows, I have a good chance of hitting the same cluster. But I still have no guarantee. Many years ago, SEO people figured that some Google IPs would serve new versions of the ranking algorithms earlier than the rest. Even those were not stable and definitely not a guarantee, given how GSLB works: https://searchengineland.com/google-caffeine-now-live-on-one-google-data-center-30697 https://searchengineland.com/google-caffeine-now-live-on-one... I have no clue how DDG works, but I am familiar with the Google search infrastructure as of several years ago and if you told me that the same query should always return the same identical results, I would tell you that you just don't know how Google works, even if you ignore personal results. That made monitoring and catching regressions not fun. It's better than running searches days or weeks apart, but running queries at the same time as they did does not guarantee anything, sorry. Keep also in mind that the average query goes through thousands of machines, according to public statements. Behavior at the long tail can differ for obvious reasons. From a Jeff Dean talk, https://static.googleusercontent.com/media/research.google.com/en//people/jeff/Stanford-DL-Nov-2010.pdf https://static.googleusercontent.com/media/research.google.c... | Some issues: | –Variance: query touches 1000s of machines, not dozens | • e.g. randomized cron jobs caused us trouble for a while | -Availability: 1 or few replicas of each doc’s index data | • Availability of index data when machine failed (esp for important docs): replicate important docs (see also the slides about Universal search, as well as patterns such as the elastic systems and the different tiers)