What you may be referring to is systemd treating resolv.conf entries as identical DNS servers, where they used to be processed sequentially. Previous discussion

What you may be referring to is systemd treating resolv.conf entries as identical DNS servers, where they used to be processed sequentially. Previous discussion: https://news.ycombinator.com/item?id=15228940 https://news.ycombinator.com/item?id=15228940 It's a breaking change for some users. I remember experiencing that bug.