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does anyone know when the arp cache in OS X Lion gets emptied? Or which automatism causes it to get emptied? Is it a time period, which can be set somewhere?


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up vote 1 down vote accepted

According to arp(4) on an OS X Lion system:

 The ARP cache is stored in the system routing table as dynamically-created host
 routes.  The route to a directly-attached Ethernet network is installed as a
 ``cloning'' route (one with the RTF_CLONING flag set), causing routes to individual
 hosts on that network to be created on demand.  These routes time out periodically
 (normally 20 minutes after validated; entries are not validated when not in use). 

You can manually manage the ARP table using the arp command.

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