Re: Strange IP conflict
- From: "Kerry Brown" <kerry@xxxxxxxxxxxxxxxxxxx*a*m>
- Date: Tue, 19 Sep 2006 10:09:55 -0700
Glad to hear you got it sorted out.
--
Kerry
MS-MVP Windows - Shell/User
http://www.vistahelp.ca
dilan.weerasinghe@xxxxxxxxx wrote:
Kerry Brown wrote:
dilan.weerasinghe@xxxxxxxxx wrote:
Hi
We are running a Windows 2000/3 network. One Windows 2000 SP4 DHCP
server. All one subnet, 192.168.1.0/24. On the DHCP server,
addresses 192.168.1.1 - 25 are on the IP range excluded from
distribution.
One of our Windows XP machines, machine A, has an address of
192.168.1.16 statically assigned to it via its LAN card's network
properties.
Today, I was unable to RDP into it, so I went over and it said that
there had been an IP Address conflict. I logged in, and it wouldn't
allow itself to use the .16 address, so was stuck on 192.168.0.0
with no network connectivity. It has no other LAN cards.
I went to another machine, and pinged 192.168.1.16 and received four
replies. I then pinged Machine A by name, and received four replies
from 192.168.1.16, which I thought was strange. I then checked the
DHCP leases, and no machine has been given 192.168.1.16. Also,
running nbtstat -a 192.168.1.16 showed no computers had that
address.
We then changed the address of Machine A to 192.168.1.20. However,
if I try to ping Machine A by name, the address I still get the ping
reply back from is 192.168.1.16. And if I ping 192.168.1.16, I
always get four replies.
We have a Cisco PIX firewall that is configured not to act as a DHCP
server, and a Cisco 2501 router which does not have a LAN interface,
so can't be those either.
Does anyone have any ideas?
I'm assuming you tried rebooting the pc in question? Rather than
static IP's I like to use reservations for pc's or devices that need
a static address. This makes sure that the DNS, WINS, NETBIOS and
possibly other settings are consistant among all devices on the LAN.
Try setting a reservation for the pc then reboot it. If that doesn't
fix it do you have wireless in the mix? If you turn off the pc can
you still ping 192.168.1.16?
--
Kerry
MS-MVP Windows - Shell/User
http://www.vistahelp.ca
Hi
Yup, I did reboot the machine to no avail. I agree, we should have
used a reservation for this machine on the DHCP server, but never got
round to doing it.
Today, we updated the DNS so that the A/PTR records for Machine A
corresponded to 192.168.1.20. If I was to ping Machine A by hostname,
then the reply came from 192.168.1.20. Unfortunately, pinging
192.168.1.16 still gave four replies, even if this machine was off.
I then ran arp -a on the machine that was pinging the two addresses
and found the MAC addresses that the pings were coming back from
(which were completely different).
Upon checking http://www.techzoom.net/mac/index.asp, it showed that
the MAC address tied to 192.168.1.16 was manufactured by Samsung -
also the make of our digital phone system.
We examined the Samsung Digital switch, and there was indeed a cable
running from there to our main 3COM switch. Apparently, this was
connected to a NIC on the Samsung side that was originally meant to
allow phone engineers to remote access in. If we disconnected the
cable, we couldn't ping 192.168.1.16. So all sorted!
Thanks for the help.
.
- References:
- Strange IP conflict
- From: dilan . weerasinghe
- Re: Strange IP conflict
- From: Kerry Brown
- Re: Strange IP conflict
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