help: can't find route to certain site via specified ISP connection

sorry if this is not the correct place to post this.

 

we have one F5 LTM box, with two ISP connections. we setup SNAT for some nodes and mapping their outgoing traffic to IP of ISP A. however we found one site on Internet is not reachable on these nodes. below is the tracert:

 

C:\Documents and Settings\usr>tracert cn.soap.search.msn.com

 

 

Tracing route to failoversoap.search.msn.com.cn.akadns.net [202.89.236.250]

 

over a maximum of 30 hops:

 

 

1 <1 ms <1 ms <1 ms 10.0.4.1

 

2 <1 ms <1 ms <1 ms 192.168.0.1

 

3 * * * Request timed out.

 

4 * * * Request timed out.

 

5 * * * Request timed out.

 

6 * * * Request timed out.

 

7 * * * Request timed out.

 

8 * * * Request timed out.

 

9 * * * Request timed out.

 

10 * * * Request timed out.

 

11 * * * Request timed out.

 

12 * * * Request timed out.

 

13 * * * Request timed out.

 

14 * * * Request timed out.

 

15 * * * Request timed out.

 

these SNAT nodes ARE able to access other Internet sites, and if we disable the SNAT, everything is fine.

 

It seems that the network package can't get out of internal network via ISP A's connection.

 

anybody has similar experience? where shall I take a look at? any advice will be apprecieated.