Add logging when a name doesn't resolve

main.go

@@ -89,7 +89,7 @@ func NewDNSSECExporter(timeout time.Duration, resolvers []string, logger Logger)
 			},
 		),
 		dnsClient: &dns.Client{
-			Net:     "tcp",
+			// Net:     "tcp",
 			Timeout: timeout,
 		},
 		resolvers: resolvers,
@@ -176,6 +176,12 @@ func (e *Exporter) resolve(zone, record, recordType, resolver string) (resolves
 		!response.CheckingDisabled &&
 		response.Rcode == dns.RcodeSuccess
 
+	if !resolves {
+		log.Printf("%s AuthenticatedData: %t", hostname(zone, record), response.AuthenticatedData)
+		log.Printf("%s CheckingDisabled:  %t", hostname(zone, record), response.AuthenticatedData)
+		log.Printf("%s RcodeSuccess    :  %s", hostname(zone, record), dns.RcodeToString[response.Rcode])
+	}
+
 	// If multiple RRSIGs cover our record, return the one that will expire the earliest.
 	for _, rr := range response.Answer {
 		if rrsig, ok := rr.(*dns.RRSIG); ok {