The default ARP cache timeout varies widely between systems. Many host systems, such as Windows and Linux machines have a short timeout between 5 and 20 minutes. Network devices, such as routers are often much longer. Cisco IOS routers default to 4 hours. While many router operators believe 4 hours is absurdly long and change the default time to a few minutes, others believe 4 hours is too short, and increase this time to 8 hours or more.
What is Cisco's recommendation on changing the timeout values? Is there any efficiencies lost or gained by lowering or increasing (i.e. addtional memory resources, cpu increase, etc.)
