diff --git a/plugin.go b/plugin.go
index 8891dfb..391d6a1 100644
--- a/plugin.go
+++ b/plugin.go
@@ -75,6 +75,7 @@ func (p *RFC2136) Name() string { return "rfc2136" }
 //	Anything else  → pass through to Next (the auto plugin handles
 //	                 queries against the zone files we maintain).
 func (p *RFC2136) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
+	log.Infof("ServeDNS: opcode=%d (UPDATE=5) qcount=%d", r.Opcode, len(r.Question))
 	if r.Opcode == dns.OpcodeUpdate {
 		if err := p.checkTSIG(w, r); err != nil {
 			log.Warningf("UPDATE rejected: %v", err)