A gray triangle indicates success, but no changes. The DNS service doesn't support change detection, so will always be gray until a failure occurs. That's also why the Last Change is "n/a", for not applicable.

By default Simon uses time-sensitive status icons, which are gray when successful but nothing has changed or failed, bright green when a change occurs, slowly fading back to gray over time, bright red when a failure occurs, and orange when it recovers from a failure, again slowly fading back to gray over time.

If you would prefer simple green = success, red = failure status icons, change the General Preference to "Use simple status icons". See the User Guide for more info.