https://downloads.powerdns.com/patches/2014-02/3.6.1.patch

diff --git a/pdns_recursor.cc b/pdns_recursor.cc
index f1ef93c..8e43d6e 100644
--- a/pdns_recursor.cc
+++ b/pdns_recursor.cc
@@ -550,7 +550,14 @@ void startDoResolve(void *p)
 
     // if there is a RecursorLua active, and it 'took' the query in preResolve, we don't launch beginResolve
     if(!t_pdl->get() || !(*t_pdl)->preresolve(dc->d_remote, g_listenSocketsAddresses[dc->d_socket], dc->d_mdp.d_qname, QType(dc->d_mdp.d_qtype), ret, res, &variableAnswer)) {
-      res = sr.beginResolve(dc->d_mdp.d_qname, QType(dc->d_mdp.d_qtype), dc->d_mdp.d_qclass, ret);
+       try {
+         res = sr.beginResolve(dc->d_mdp.d_qname, QType(dc->d_mdp.d_qtype), dc->d_mdp.d_qclass, ret);
+       }
+       catch(ImmediateServFailException &e) {
+         L<<Logger::Error<<"Sending SERVFAIL during resolve of '"<<dc->d_mdp.d_qname<<"' because: "<<e.reason<<endl;
+
+         res = RCode::ServFail;
+       }
 
       if(t_pdl->get()) {
         if(res == RCode::NoError) {
diff --git a/syncres.cc b/syncres.cc
index 4dc78b4..d09e44b 100644
--- a/syncres.cc
+++ b/syncres.cc
@@ -923,6 +923,7 @@ int SyncRes::doResolveAt(set<string, CIStringCompare> nameservers, string auth,
           }
           else {
             s_outqueries++; d_outqueries++;
+            if(d_outqueries > 50) throw ImmediateServFailException("more than 50 queries sent while resolving "+qname);
           TryTCP:
             if(doTCP) {
               LOG(prefix<<qname<<": using TCP with "<< remoteIP->toStringWithPort() <<endl);
diff --git a/syncres.hh b/syncres.hh
index 5182527..b22de89 100644
--- a/syncres.hh
+++ b/syncres.hh
@@ -593,6 +593,13 @@ private:
   static AtomicCounter s_currentConnections; //!< total number of current TCP connections
 };
 
+class ImmediateServFailException
+{
+public:
+  ImmediateServFailException(string r){reason=r;};
+
+  string reason; //! Print this to tell the user what went wrong
+};
 
 struct RemoteKeeper
 {