Learned something interesting from support about flow preferences today. If you are using dual connections for your MX and you setup an internet traffic flow preference it doesn't include ICMP traffic. Even if you have the protocol set to 'Any'. ICMP will always go out whatever you have designated as the 'Primary Uplink'. Caused me a little grief today while troubleshooting so hopefully it can save you a little time.
Adam R MS | CISSP, CISM, VCP, MCITP, CCNP, ITILv3, CMNO
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