by mk

Here's the technical implementation:

https://duck.co/help/results/yahoo-technical-implementation

To get access to the most relevant Yahoo technology, due to contractual obligations that call has to be associated with a Yahoo domain, in this case, duckduckgo-owned-server.yahoo.net. To make sure this call does not violate our privacy policy, Yahoo delegates this domain to us via DNS. In other words, duckduckgo-owned-server.yahoo.net is operated by DuckDuckGo and runs solely on our servers. Yahoo does not have access to these servers in any respect.