A custom domain that worked on Tuesday can fail on Friday without anyone touching your product. Here are the ways a live connection degrades after setup, and why watching for drift matters as much as writing the records in the first place.

The copy-paste DNS ticket recurs forever: wrong MX priority, a missing trailing dot, a TXT record split across two lines. When the identical failure shows up a hundred times, it is a structural defect, not a user mistake. One-click setup deletes the whole category.