The configuration seems correct; can you run through the steps here to verify that the DNS record for the headless service returns the node addresses? https://kubernetes.io/docs/tasks/administer-cluster/dns-debugging-resolution/
–> run nslookup hivemq-discovery.kube-hivemq.svc.cluster.local. in the debug container (dig is also a good tool for this)
Is the error log consistently happening in this case (i.e. every 30 seconds) or is it intermittent, e.g. only happens every few hours or in random intervals?
i have observed that on some K8s clusters the DNS service intermittently will return NXDOMAIN, other errors or straight up time out(like in your case), which is not usually a problem when the cluster is already established.
You might also want to look into how CoreDNS is behaving in this case, maybe it’s in a failure state and restarting or something along those lines. You could also check whether it happens to be the same CoreDNS node that is failing (check the IP in the DnsNameResolverTimeoutException: [/10.233.0.10:53] query timed out statement)
If the error log only happens intermittently and scaling up/down behaves normally otherwise it should be safe to ignore the log statement.