diff --git a/action.go b/action.go
index 6eebd74..6bff52f 100644
--- a/action.go
+++ b/action.go
@@ -274,10 +274,13 @@ func (service *Service) handleReverseLookup(ctx context.Context, values map[stri
 func (service *Service) handleServe(ctx context.Context, values map[string]any) (any, bool, error) {
 	_ = ctx
 	bind, _ := stringActionValueOptional(values, "bind")
-	port, err := intActionValue(values, "port")
+	port, portProvided, err := intActionValueOptional(values, "port")
 	if err != nil {
 		return nil, false, err
 	}
+	if !portProvided {
+		port = service.dnsPort
+	}
 	result, err := service.Serve(bind, port)
 	if err != nil {
 		return nil, false, err
@@ -337,3 +340,18 @@ func intActionValue(values map[string]any, key string) (int, error) {
 		return 0, fmt.Errorf("%w: %s", errActionMissingValue, key)
 	}
 }
+
+func intActionValueOptional(values map[string]any, key string) (int, bool, error) {
+	if values == nil {
+		return 0, false, nil
+	}
+	_, exists := values[key]
+	if !exists {
+		return 0, false, nil
+	}
+	value, err := intActionValue(values, key)
+	if err != nil {
+		return 0, false, err
+	}
+	return value, true, nil
+}
diff --git a/go.mod b/go.mod
index 3a60f50..92f2952 100644
--- a/go.mod
+++ b/go.mod
@@ -4,8 +4,6 @@ go 1.22
 
 require github.com/miekg/dns v1.1.62
 
-require github.com/patrickmn/go-cache v2.1.0+incompatible
-
 require (
 	golang.org/x/mod v0.18.0 // indirect
 	golang.org/x/net v0.27.0 // indirect
diff --git a/go.sum b/go.sum
index 26556ce..95e8194 100644
--- a/go.sum
+++ b/go.sum
@@ -1,7 +1,5 @@
 github.com/miekg/dns v1.1.62 h1:cN8OuEF1/x5Rq6Np+h1epln8OiyPWV+lROx9LxcGgIQ=
 github.com/miekg/dns v1.1.62/go.mod h1:mvDlcItzm+br7MToIKqkglaGhlFMHJ9DTNNWONWXbNQ=
-github.com/patrickmn/go-cache v2.1.0+incompatible h1:HRMgzkcYKYpi3C8ajMPV8OFXaaRUnok+kx1WdO15EQc=
-github.com/patrickmn/go-cache v2.1.0+incompatible/go.mod h1:3Qf8kWWT7OJRJbdiICTKqZju1ZixQ/KpMGzzAfe6+WQ=
 golang.org/x/mod v0.18.0 h1:5+9lSbEzPSdWkH32vYPBwEpX8KwDbM52Ud9xBUvNlb0=
 golang.org/x/mod v0.18.0/go.mod h1:hTbmBsO62+eylJbnUtE2MGJUyE7QWk4xUqPFrRgJ+7c=
 golang.org/x/net v0.27.0 h1:5K3Njcw06/l2y9vpGCSdcxWOYHOUk3dVNGDXN+FvAys=
diff --git a/service_test.go b/service_test.go
index 3f98ebb..c61abb1 100644
--- a/service_test.go
+++ b/service_test.go
@@ -2105,6 +2105,45 @@ func TestServiceHandleActionResolveAndTXTAndAll(t *testing.T) {
 	}
 }
 
+func TestServiceHandleActionServeDefaultsPortFromServiceConfiguration(t *testing.T) {
+	desiredPort := pickFreeTCPPort(t)
+	service := NewService(ServiceOptions{
+		DNSPort: desiredPort,
+		Records: map[string]NameRecords{
+			"gateway.charon.lthn": {
+				A: []string{"10.10.10.10"},
+			},
+		},
+	})
+
+	payload, ok, err := service.HandleAction(ActionServe, map[string]any{
+		"bind": "127.0.0.1",
+	})
+	if err != nil {
+		t.Fatalf("expected serve action to default port when omitted: %v", err)
+	}
+	if !ok {
+		t.Fatal("expected serve action to succeed with omitted port")
+	}
+	dnsServer, ok := payload.(*DNSServer)
+	if !ok {
+		t.Fatalf("expected DNSServer payload, got %T", payload)
+	}
+	if dnsServer == nil {
+		t.Fatal("expected dns server from serve action")
+	}
+
+	_, port, err := net.SplitHostPort(dnsServer.DNSAddress())
+	if err != nil {
+		t.Fatalf("expected service address to include port: %v", err)
+	}
+	if port != strconv.Itoa(desiredPort) {
+		t.Fatalf("expected configured DNS port %d, got %q", desiredPort, port)
+	}
+
+	_ = dnsServer.Close()
+}
+
 func TestServiceActionNamesExposeAllRFCActions(t *testing.T) {
 	service := NewService(ServiceOptions{})