Mailinglist Archive: opensuse (2358 mails)

[alexm@xxxxxxxxxxx (alex medvedev)]

Hi,

On Wed, 13 Oct 1999, JJ Hendriksen wrote:
> I've got a strange problem. I've got a local network, four machines
> connected to it. I have set up demand dialing, ip forwarding and some 
> firewalling rules (using ipchains). However, sometimes my dns does not
> work, I can only ping IP addresses, all dns lookups fail.

Can you ping your nameserver ip address at this point?
do you run your own nameserver or use isp's?

> But the next
> day or so (for example), everything works fine again. I've spent a lot
> of time searching for the problem, and have found that my arp table on
> my server is corrupt. There is one line with an incomplete MAC address.

what do you mean "incomplete"? not full address or
xx.xx.xx.xx @ <INCOMPLETE> 
if second is the case, then your system tried to contact the indicated ip
address and that address did not respond to the arp request (cable problem
?, host down?)

> I think this is causing my problem (strange but true).. It is indeed
> very strange that this problem only affects the dns lookups, but I
> could not give an explanation.. 

if the ip address in the arp table with <incomplete> is your nameserver ip
address then there is nothing strange here...

> does anyone know how I can rebuild my arp table by hand? So that I
> can remove the invalid line and enter the correct one? As far as I
> know arp is a system utility that works completely on it's own..

although you can certainly implant arp entries into your table, i do not
see a good reason for that, unless you use bootp or something...
see "man arp" for good examples.

bye,

-alexm


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