diff --git a/internal/dhcp/dhcp_test.go b/internal/dhcp/dhcp_test.go
index a2d5e60..94c7d7b 100644
--- a/internal/dhcp/dhcp_test.go
+++ b/internal/dhcp/dhcp_test.go
@@ -109,6 +109,32 @@ func TestGenerateConfig_NoDefaultGateway(t *testing.T) {
 	}
 }
 
+func TestGenerateConfig_NoDefaultGatewaySuppressesRouterOption(t *testing.T) {
+	conf := newConf(t, "192.168.1.0/29")
+	conf.DefaultGateway = nil
+	path, _, _ := GenerateConfig(conf)
+	content, _ := os.ReadFile(path)
+
+	if !strings.Contains(string(content), "\ndhcp-option=3\n") {
+		t.Errorf("dhcp-option=3 nue absente : sans elle dnsmasq annonce sa propre adresse comme routeur\n%s", content)
+	}
+}
+
+func TestGenerateConfig_VxlanEmitsNoRouterOption(t *testing.T) {
+	conf := newConf(t, "192.168.1.0/29")
+	conf.DefaultGateway = nil
+
+	path, _, _ := GenerateConfig(conf)
+	content, _ := os.ReadFile(path)
+
+	if !strings.Contains(string(content), "dhcp-option=121,") {
+		t.Fatalf("dhcp-option=121 attendue pour un subnet vxlan :\n%s", content)
+	}
+	if strings.Contains(string(content), "dhcp-option=3,") {
+		t.Errorf("un subnet vxlan est privé : aucune route par défaut ne doit être émise\n%s", content)
+	}
+}
+
 func TestGenerateConfig_ContainsVPCRoute(t *testing.T) {
 	conf := newConf(t, "192.168.1.0/29")
 	path, _, _ := GenerateConfig(conf)
diff --git a/internal/dhcp/generate.go b/internal/dhcp/generate.go
index 2b6c72f..40250f6 100644
--- a/internal/dhcp/generate.go
+++ b/internal/dhcp/generate.go
@@ -19,6 +19,8 @@ func GenerateConfig(c Config) (string, map[string]string, error) {
 	}
 	if c.DefaultGateway != nil {
 		fmt.Fprintf(&sb, "dhcp-option=3,%s\n", c.DefaultGateway.String())
+	} else {
+		fmt.Fprintf(&sb, "dhcp-option=3\n")
 	}
 	fmt.Fprintf(&sb, "dhcp-option=6,1.1.1.1,8.8.8.8\n\n")
 
diff --git a/internal/dhcp/struct.go b/internal/dhcp/struct.go
index bf6ace9..bacb1e0 100644
--- a/internal/dhcp/struct.go
+++ b/internal/dhcp/struct.go
@@ -10,7 +10,7 @@ type Config struct {
 	Network        *net.IPNet
 	VPCGateway     net.IP     // next-hop for VPCRoute (option 121)
 	VPCRoute       *net.IPNet // if non-nil, emit dhcp-option=121,VPCRoute,VPCGateway
-	DefaultGateway net.IP     // if non-nil, emit dhcp-option=3,DefaultGateway
+	DefaultGateway net.IP     // if non-nil, emit dhcp-option=3,DefaultGateway; if nil, emit a bare dhcp-option=3 to suppress the dnsmasq default
 	Name           string
 	ConfDir        string
 }