dns: implement light dns caching
Cache DNS results very lightly in node. Strawman: Cache for 1 second, refresh in the background, and delete cache after 1 second.
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
Cache DNS results very lightly in node. Strawman: Cache for 1 second, refresh in the background, and delete cache after 1 second.