arp cache incomplete entries

[Panayiotis Karabassis <panayk@gmail.com>]

Hi,

I've noticed that, often, after establishing a connection to the local
network, important entries in the ARP cache, such as that of my
nameserver, appear as 'incomplete' and have not an associated hardware
address. Connection to these hosts often fails.

What are the possible reasons why this could happen? And is there any
way to repopulate the ARP cache without reconnecting? How is the ARP
cache populated in the first place?

Unfortunately, I often have to reset my router, and hence LAN
connections, because of problems with my ISP, so this problem appears
frequently.

Thanks,
Panayiotis