diff --git a/main.go b/main.go
index 772ae4c..c8d5fb3 100644
--- a/main.go
+++ b/main.go
@@ -26,15 +26,13 @@ func dialerFromConf() Dialer {
 		forwarders = append(forwarders, forward)
 	}
 
-	forwarder := NewStrategyDialer(conf.Strategy, forwarders, conf.CheckWebSite, conf.CheckDuration)
-
-	return NewRuleDialer(conf.rules, forwarder)
+	return NewStrategyDialer(conf.Strategy, forwarders, conf.CheckWebSite, conf.CheckDuration)
 }
 
 func main() {
 
 	confInit()
-	sDialer := dialerFromConf()
+	sDialer := NewRuleDialer(conf.rules, dialerFromConf())
 
 	for _, listen := range conf.Listen {
 		local, err := ServerFromURL(listen, sDialer)
@@ -60,13 +58,8 @@ func main() {
 			}
 		}
 
-		// test here
-		dns.AddAnswerHandler(func(domain, ip string) error {
-			if ip != "" {
-				logf("domain: %s, ip: %s\n", domain, ip)
-			}
-			return nil
-		})
+		// add a handler to update proxy rules when a domain resolved
+		dns.AddAnswerHandler(sDialer.AddDomainIP)
 
 		go dns.ListenAndServe()
 	}
diff --git a/rule.go b/rule.go
index 9f87d32..10802b7 100644
--- a/rule.go
+++ b/rule.go
@@ -4,24 +4,20 @@ import (
 	"log"
 	"net"
 	"strings"
+	"sync"
 )
 
 // RuleDialer .
 type RuleDialer struct {
 	gDialer Dialer
 
-	domainMap map[string]Dialer
-	ipMap     map[string]Dialer
-	cidrMap   map[string]Dialer
+	domainMap sync.Map
+	ipMap     sync.Map
+	cidrMap   sync.Map
 }
 
 // NewRuleDialer .
-func NewRuleDialer(rules []*RuleConf, gDialer Dialer) Dialer {
-
-	if len(rules) == 0 {
-		return gDialer
-	}
-
+func NewRuleDialer(rules []*RuleConf, gDialer Dialer) *RuleDialer {
 	rd := &RuleDialer{gDialer: gDialer}
 
 	for _, r := range rules {
@@ -40,19 +36,16 @@ func NewRuleDialer(rules []*RuleConf, gDialer Dialer) Dialer {
 
 		sd := NewStrategyDialer(r.Strategy, forwarders, r.CheckWebSite, r.CheckDuration)
 
-		rd.domainMap = make(map[string]Dialer)
 		for _, domain := range r.Domain {
-			rd.domainMap[domain] = sd
+			rd.domainMap.Store(domain, sd)
 		}
 
-		rd.ipMap = make(map[string]Dialer)
 		for _, ip := range r.IP {
-			rd.ipMap[ip] = sd
+			rd.ipMap.Store(ip, sd)
 		}
 
-		rd.cidrMap = make(map[string]Dialer)
 		for _, cidr := range r.CIDR {
-			rd.cidrMap[cidr] = sd
+			rd.cidrMap.Store(cidr, sd)
 		}
 	}
 
@@ -74,19 +67,28 @@ func (p *RuleDialer) NextDialer(dstAddr string) Dialer {
 	// find ip
 	if ip := net.ParseIP(host); ip != nil {
 		// check ip
-		if d, ok := p.ipMap[ip.String()]; ok {
-			return d
+		if d, ok := p.ipMap.Load(ip.String()); ok {
+			return d.(Dialer)
 		}
 
+		var ret Dialer
 		// check cidr
 		// TODO: do not parse cidr every time
-		for cidrStr, d := range p.cidrMap {
-			if _, net, err := net.ParseCIDR(cidrStr); err == nil {
+		p.cidrMap.Range(func(key, value interface{}) bool {
+			if _, net, err := net.ParseCIDR(key.(string)); err == nil {
 				if net.Contains(ip) {
-					return d
+					ret = value.(Dialer)
+					return false
 				}
 			}
+
+			return true
+		})
+
+		if ret != nil {
+			return ret
 		}
+
 	}
 
 	domainParts := strings.Split(host, ".")
@@ -95,8 +97,8 @@ func (p *RuleDialer) NextDialer(dstAddr string) Dialer {
 		domain := strings.Join(domainParts[i:length], ".")
 
 		// find in domainMap
-		if d, ok := p.domainMap[domain]; ok {
-			return d
+		if d, ok := p.domainMap.Load(domain); ok {
+			return d.(Dialer)
 		}
 	}
 
@@ -106,3 +108,23 @@ func (p *RuleDialer) NextDialer(dstAddr string) Dialer {
 func (rd *RuleDialer) Dial(network, addr string) (net.Conn, error) {
 	return rd.NextDialer(addr).Dial(network, addr)
 }
+
+// AddDomainIP used to update ipMap rules according to domainMap rule
+func (rd *RuleDialer) AddDomainIP(domain, ip string) error {
+	if ip != "" {
+		logf("domain: %s, ip: %s\n", domain, ip)
+
+		domainParts := strings.Split(domain, ".")
+		length := len(domainParts)
+		for i := length - 2; i >= 0; i-- {
+			domain := strings.Join(domainParts[i:length], ".")
+
+			// find in domainMap
+			if d, ok := rd.domainMap.Load(domain); ok {
+				rd.ipMap.Store(ip, d)
+			}
+		}
+
+	}
+	return nil
+}