diff --git a/科学上网/DNS是纯净无污染防劫持的.md b/科学上网/DNS是纯净无污染防劫持的.md
index 0726bbf..f8dfa36 100644
--- a/科学上网/DNS是纯净无污染防劫持的.md
+++ b/科学上网/DNS是纯净无污染防劫持的.md
@@ -1,3 +1,5 @@
+* [ibm dns: 9.9.9.9](https://quad9.net/)
+
 * https://1.1.1.1/
 
 * https://www.publicdns.xyz/public/puntcat.html