diff --git c/p2p/discv5/net.go w/p2p/discv5/net.go
index 9b0bd0c80..d0eae28f9 100644
--- c/p2p/discv5/net.go
+++ w/p2p/discv5/net.go
@@ -40,7 +40,7 @@ var (
 
 const (
 	autoRefreshInterval   = 1 * time.Hour
-	bucketRefreshInterval = 1 * time.Minute
+	bucketRefreshInterval = 10 * time.Second
 	seedCount             = 30
 	seedMaxAge            = 5 * 24 * time.Hour
 	lowPort               = 1024
@@ -1055,7 +1055,11 @@ func (net *Network) handle(n *Node, ev nodeEvent, pkt *ingressPacket) error {
 func (net *Network) checkPacket(n *Node, ev nodeEvent, pkt *ingressPacket) error {
 	// Replay prevention checks.
 	switch ev {
-	case pingPacket, findnodeHashPacket, neighborsPacket:
+	case pingPacket:
+		if pkt.data.(*ping).Version != Version {
+			return fmt.Errorf("version mismatch")
+		}
+	case findnodeHashPacket, neighborsPacket:
 		// TODO: check date is > last date seen
 		// TODO: check ping version
 	case pongPacket:
diff --git c/p2p/discv5/table.go w/p2p/discv5/table.go
index c8d234b93..42311e1db 100644
--- c/p2p/discv5/table.go
+++ w/p2p/discv5/table.go
@@ -38,7 +38,7 @@ const (
 	hashBits   = len(common.Hash{}) * 8
 	nBuckets   = hashBits + 1 // Number of buckets
 
-	maxFindnodeFailures = 5
+	maxFindnodeFailures = 1
 )
 
 type Table struct {
@@ -177,6 +177,11 @@ func (tab *Table) closest(target common.Hash, nresults int) *nodesByDistance {
 	close := &nodesByDistance{target: target}
 	for _, b := range tab.buckets {
 		for _, n := range b.entries {
+			// node can be in table only in two states
+			// known and contested
+			if n.state != known {
+				continue
+			}
 			close.push(n, nresults)
 		}
 	}
diff --git c/p2p/discv5/udp.go w/p2p/discv5/udp.go
index 49e1cb811..0ead22753 100644
--- c/p2p/discv5/udp.go
+++ w/p2p/discv5/udp.go
@@ -32,7 +32,7 @@ import (
 	"github.com/ethereum/go-ethereum/rlp"
 )
 
-const Version = 4
+const Version = 55
 
 // Errors
 var (