diff --git a/etc/quantum.conf b/etc/quantum.conf
index ab8921e4f..f86434d81 100644
--- a/etc/quantum.conf
+++ b/etc/quantum.conf
@@ -45,6 +45,8 @@ api_paste_config = api-paste.ini
 # Enable or disable bulk create/update/delete operations
 # allow_bulk = True
 # Enable or disable overlapping IPs for subnets
+# Attention: the following parameter MUST be set to False if Quantum is
+# being used in conjunction with nova security groups and/or metadata service.
 # allow_overlapping_ips = False
 
 # RPC configuration options. Defined in rpc __init__