Strange IP conflict

D

dilan.weerasinghe

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?
 
S

Sandgroper

Habib said:
After Register this site:

http://greenhorse.com/join_now.ghc?r=102192444

I Reply you
Click to expand...

That a bit rough isn't it ????
A person posts a problem about a Windows 2000 network problem in a MS
newsgroup on a Microsoft news server and you try to hijack the person to
your website and then ask him to join some crappy service to PAY for your
advice.

You are nothing but a spammer and your email address and web page should be
black banned from the Microsoft news server.


--
 
E

Edwin vMierlo

Habib,

I would like you to ask you to stop posting these messages
We are all volunteering to help each other, which the beauty and the power
of these newsgroups.

If you know the answer, or know can help people in these communities, please
do so voluntary.
If you don't want to voluntary help, please stop posting.
If you have a question, post it, and we will try to help you.

Thanks !
Edwin.
 
K

Kerry Brown

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?
Click to expand...

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?
 
D

dilan.weerasinghe

Kerry said:
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?
Click to expand...

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.
 

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