dhcpd assign duplicated IP address

[Bill Moran]

In response to Zhang Weiwu <zhangweiwu at realss.com>:

<snip>
> 
> P.S. In recent days we some times got another network problem and I'm
> not sure if it's related to this DHCP server behavior. It happens on
> both Linux and Windows hosts that a host suddenly is no longer
> accessible (Ping no response). Check 'arp -a' on other hosts shows the
> host being accessed have wrong Mac Address. e.g. yesterday
> 218.193.55.195 suddenly become in-accessible, this host is Linux and we
> got this behavior on a nearby host:
> 
> sappho # arping 218.193.55.195
> Unicast reply from 218.193.55.195 [00:0F:EA:4B:82:58]  0.638ms
> Unicast reply from 218.193.55.195 [00:0F:EA:4B:82:58]  0.637ms
> Sent 113 probes (1 broadcast(s))
> Received 113 response(s)
> sappho # arp -a 218.193.55.195
> ? (218.193.55.195) at 00:02:2A:C1:53:87 [ether] on eth0
> 
> arping reply is different from arp cache. This host become accessible
> the next day. Strange. Are these two problems related?

You have something seriously wrong somewhere.  They may be related but
there's not enough information here to be sure.  Consider installing
arpwatch on one or more systems and see if the reports it sends narrow
down the problem.

-- 
Bill Moran
http://www.potentialtech.com