Add debug statement for DNS challenge

dns_challenge.go

@@ -110,6 +110,7 @@ func (d *dnsValidator) Fulfill(ctx context.Context, client *acme.Client, domain
 }
 
 func (d *dnsValidator) updateNS(ctx context.Context, ns, zone, fqdn, value string, remove bool) error {
+	log.Printf("updateNS(%s, %s, %s, %s, %v)", ns, zone, fqdn, value, remove)
 	rrs := d.makeRR(fqdn, value, rfc2136Timeout)
 	m := d.makeMsg(zone, rrs, remove)
 	c := d.client()