If the MAC address that you are looking for does not show up in the list, this may be due to one of the following:

  1.  You are not monitoring all of the routers in your environment
  2.  The device communicates with a local server and thus does not need to communicate with any routers (in which case, you should add SNMP support to the local server and add it to monitoring
  3.  When “Update” was clicked, we show the current ARP cache information on all of the devices. MAC addresses will expire out of ARP caches after 5 minutes (typically) of non-use. If the device is quiet (dormant and not communicating), then nobody will know about it’s information until it speaks up.