Application Development Software

Hi,
Am very confused as how to set the value for java.naming.provider.url if this points to multiple urls.
For eg :
if i need to map two urls (different host and port) how should i do that??
Which one of the following is correct??

1) java.naming.provider.url = t3://server1:port1,server2:port2
2) java.naming.provider.url =t3://server1:port1,t3://server2:port2


or both the ways are wrong??
am not able to reach the engine if i configure like this. Please advice..
Also kindly mention can i use the ip of the server instead of the name???



Thanks,
Charan