Caching is always optional. If you want sophisticated control over caching, or just no caching at all, you can do recursive lookups directly. Some existing DNS libraries can do recursive lookups directly, including libunbound. Ideally you would do caching of TLD nameserver addresses so you're not hammering the root servers for each query. But otherwise I don't think it's necessarily a big deal for a monitoring service to query the .de nameservers every time it checks example.de. If you had a monitor check every 5 minutes for example.de, it's only a 12x load factor between querying .de directly every check versus once per hour. Unless you're AWS Route53, that's not much of a difference relative to the traffic TLD servers handle even if you were checking tens of thousands of domains. Clamping your cache at 1 hour is probably already a much greater load factor. The .de nameservers return a TTL of 1 day for the example.de NS RR sets, so that's already a 24x factor right there. At that point you're clearly giving the .de nameservers the middle finger and relying on your own judgement of what it means to play nice.