diff --git a/constant/ecs.go b/constant/ecs.go
new file mode 100644
index 00000000..78cf3292
--- /dev/null
+++ b/constant/ecs.go
@@ -0,0 +1,5 @@
+package constant
+
+import D "github.com/miekg/dns"
+
+var DefaultECS *D.OPT