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IP Conflict but no ones there...

By blastfurnace ·
I have a 100 node isolated network on a dumb hub. Two addresses went "Bad". This time, overnight the network traffic went from 17% to 59% and collisions doubled. Switching the IP address of one node fixed the problem, but a ping says no PC is onthat address. Assigning another PC to that address repeats the problem. This is a mixed network of PC's and PLC's, where I can not shut down to test except on scheduled outages. How do I find whatever is causing these conflicts?

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IP Conflict but no ones there...

by moflic In reply to IP Conflict but no ones t ...

1. Are you using arp static tables? Then that's it.
2. Try clearing the arp tables in any case, perhaps they do not update that fast to reflect the new MAC addresses you assigned IPs to.

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IP Conflict but no ones there...

by blastfurnace In reply to IP Conflict but no ones t ...

The question was auto-closed by TechRepublic

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IP Conflict but no ones there...

by bbuechler In reply to IP Conflict but no ones t ...

I'm not sure if this will help you any, but this is a past TechTip distributed by Techrepublic that may aid in finding the source of the IP conflicts:

WHO STOLE MY IP ADDRESS?!?!
If you ever get the error of having a conflicting IP address, you may
want to know who the culprit is. Even in a large corporation, this is
easier to determine than you might think. You need only arm yourself
with another workstation and the stolen IP address.

First, open a command prompt on the working workstation or server. Now,
type in the command nbtstat -a <IPAddress> where <IPAddress> is the stolen
IP. Look at the results returned. When we tested this on our NT server,
the results from the workstation were:

ROB1 <00> UNIQUE
TECHWORKS <00> GROUP
ROB1 <03> UNIQUE
REDWARDS <03> UNIQUE

Notice the two records with <03> as the NetBIOS type. One is the
machine name; the other is the logon name. Armed with the logon name,
you now know who's logged on

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IP Conflict but no ones there...

by blastfurnace In reply to IP Conflict but no ones t ...

The question was auto-closed by TechRepublic

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IP Conflict but no ones there...

by messner In reply to IP Conflict but no ones t ...

To find hostnames from IP address use the ping -a command the -a is an option that will return the hostname to an IP address. If you are not getting a response when you ping it could be the wait timeout expiring before the answer could be returned. In that case use ping -a -w #### where the #### is a time in milliseconds and the -a is ofcourse the hostname being returned. Nbtstat -A can also return a name table stored in the remote computer. Good luck.

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IP Conflict but no ones there...

by blastfurnace In reply to IP Conflict but no ones t ...

The question was auto-closed by TechRepublic

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IP Conflict but no ones there...

by matt_falenski In reply to IP Conflict but no ones t ...

I've had this problem before. I work at a school where sometimes students change an IP they can get to. We use WINS, so I can go to the WINS database, and see what PC name is associated to that IP address.
I have also recorded all MAC addresses, so I can use "ping 192.168.0.1" and then "arp -a" to get the MAC address to find the WS.
You can also get a list of manufacturers MAC addresses so that if you see a 00-30-65-52-af-3b you know that it was an Apple, or an aa-00-00-34-ac-bf was DEC. (This only helps if you dont have all the same kind of NIC. We have about 7 different brands, so I can know where to start looking then)
nbtstat -a ipaddress works pretty well, too.

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IP Conflict but no ones there...

by blastfurnace In reply to IP Conflict but no ones t ...

The question was auto-closed by TechRepublic

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IP Conflict but no ones there...

by blastfurnace In reply to IP Conflict but no ones t ...

This question was auto closed due to inactivity

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