Explanation of Juniper ping output:

The following characters can appear in the display after issuing the ping command:

* !—Reply received
* .—Timed out while waiting for a reply
* ?—Unknown packet type
* A—Address mask request message
* a—Address mask reply message
* D—Router discovery advertisement message
* d—Router discovery request message
* H—Host unreachable
* I—Information request message
* i—Information reply message
* L—TTL expired message
* M—Could not fragment, DF bit set
* m—Parameter problem message
* N—Network unreachable
* P—Protocol unreachable
* Q—Source quench
* r—Redirect message
* T—Timestamp request message
* t —Timestamp reply message
* U—Destination unreachable