diff --git a/invalid_domains.txt b/invalid_domains.txt
index 3986fbc..d72a625 100644
--- a/invalid_domains.txt
+++ b/invalid_domains.txt
@@ -204,6 +204,7 @@
 5.8.63.54
 5.9.253.173
 50.28.211.199
+500
 51.254.181.122
 51.254.19.227
 51.254.240.45