[NTLUG:Discuss] How long are MAC addresses cached?

[Leroy Tennison]

David Stanaway wrote:
> It depends on the dynamic arp cache timeout setting, but 4 hours is
> default per this article.
> 
> http://networkers-online.com/blog/2009/02/arp-caching-and-timeout/
> 
> 
> 
> 
> Neil Aggarwal wrote:
>> Hello:
>>
>> I moved an IP address to a different server than it
>> was previously on.
>>
>> I can load view the website on that IP from another 
>> server connected to the same switch as the new server, 
>> but I can't view the website from my laptop connected
>> via my ISP's wireless connection.
>>
>> I assume that is happening because the core routers
>> are still using the previous MAC address instead of
>> the new one.
>>
>> How long do they typically take to notice an update
>> of the MAC address?
>>
>> Thanks,
>> 	Neil
>>
>> --
>> Neil Aggarwal, (281)846-8957, www.JAMMConsulting.com
>> Will your e-commerce site go offline if you have
>> a DB server failure, fiber cut, flood, fire, or other disaster?
>> If so, ask about our geographically redundant database system.
>>
>>
>> _______________________________________________
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>>   
> 
> 
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> 

More details are needed.  Did you try to access the IP address or a DNS
name using the laptop (I assume the former but just checking)?  Is the
new server directly connected to the Internet or is there a device in
between such as a firewall or proxy?

The other thing which is puzzling is that "MAC address" and "IP address"
seem to be used interchangeably.  The MAC address is a layer 2 address
recognized by the switch, the IP address is a layer 3 address recognized
by the router.