Hi karthikeyan
I'm not understanding well your question, you want an application sever validating againts 10.XX.XX.XX:389 and other to 10.XX.XX.XX:3268?
I don't know which tag are you addind? any way is not a good practices to edit security.xml
In version 6.1 you only can have one security domain configured and is for all cell. You can choose federate repository and defined 2 ldap servers pointing to same server but in different ports, but you haven't granularity to choose what LDAP must use each server.
Another think is if you want LDAP server failover
pic.dhe.ibm.com/infocenter/wasinfo/v6r1/... In version 7 and higher you have security domains
pic.dhe.ibm.com/infocenter/wasinfo/v7r0/... Multiple security domains The WebSphere® Security Domains (WSD) provide the flexibility to use different security configurations in WebSphere Application Server. The WSD is also referred to as multiple security domains, or simply, security domains. You can configure different security attributes, such as the UserRegistry, for different applications. Hope this helps. Tell us if you need more support
regards