Black Box Series 5000 Reference Manual page 7

Introduction
Ping
The "ping" message is actually a query status message that may be sent to devices on the LAN to determine their
operation status. The LAN device will reply with a message if it is active.
Time and Mask server
Two other ICMP messages are used to query the time and/or subnet mask from a particular LAN device. A message
is sent to a LAN device asking for the time or mask, and the device replies appropriately.
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