diff --git a/conf/vars.xml b/conf/vars.xml
index bd1819222a..392ef3eeb5 100644
--- a/conf/vars.xml
+++ b/conf/vars.xml
@@ -92,16 +92,25 @@
   -->
 
   <!-- external_rtp_ip
-       Used as the public IP address for SDP.
-       Can be an ip address or a string like "stun:stun.server.com" 
+       Can be an one of:
+           ip address: "12.34.56.78"
+           a stun server lookup: "stun:stun.server.com"
+           a DNS name: "host:host.server.com"
+       where fs.mydomain.com is a DNS A record-useful when fs is on
+       a dynamic IP address, and uses a dynamic DNS updater.
        If unspecified, the bind_server_ip value is used.
        Used by: sofia.conf.xml dingaling.conf.xml
   -->
   <X-PRE-PROCESS cmd="set" data="external_rtp_ip=stun:stun.freeswitch.org"/>
 
   <!-- external_sip_ip
-       Used as the public IP address for SDP.
-       Can be an ip address or a string like "stun:stun.server.com" 
+      Used as the public IP address for SDP.
+       Can be an one of:
+           ip address: "12.34.56.78"
+           a stun server lookup: "stun:stun.server.com"
+           a DNS name: "host:host.server.com"
+       where fs.mydomain.com is a DNS A record-useful when fs is on
+       a dynamic IP address, and uses a dynamic DNS updater.
        If unspecified, the bind_server_ip value is used.
        Used by: sofia.conf.xml dingaling.conf.xml
   -->