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Bad IP Address in my DHCP

638 views 9 replies 4 participants last post by  Pmdown 
#1 ·
Hi Guys am Administering around 200 Computers and around 30 Digital Medical Machines , ihave a challenge with BAD IP ADDRESS in my DHCP , it has reached the extent of disconnecting Internet access to clients /Staff , i have tried to eliminate the Wireless Access Points one by one but i still get BAD IP ADDRESS, is there any one with a quick solution?
 
#5 ·
This is not an easy problem to fix.....
Start with a program like NMAP (opensource) or Angry IP Scanner (Windows Freeware) to map out your subnet.
Either program attempts to identify the equipment at each IP address, with varying results.
Use the results to compare with your DHCP server's list to account for all your known systems and IP addresses.
I understand that some systems can be set up to not allow unknown systems to work on your network.
You might have somebody who plugged a device into a live network port and set it up with a fixed IP address that they guessed at. If they split a line with their own switch, then you would have a hard time detecting it.
Are you working with managed switches? If you are, then what make and model? This would help someone guide you through any further lockdown steps
 
#6 ·
What DHCP server are you running? Windows Server ? Linux Server? The DHCP on your router? What version or Make and model?
Are you able to spot any trends? Is it the same IP address(s) that is/are consistently a problem? Are you able to identify one or both of the pieces of equipment involved with the conflict.
 
#9 ·
You didn't specify which version of MS Server you are running....
You might want to try turning on "IP Address Conflict Detection"
https://docs.microsoft.com/en-us/pr...ows-server-2008-R2-and-2008/dd183587(v=ws.10)

Is your facility operating 24/7? Would you have an opportunity to disconnect the Server running DHCP from the network for a test to see if there is another rogue DHCP server operating on the network (Plug in a device and see if it is given an IP address)
 
#10 ·
Sean am Running 4 servers , but my DHCP Server is running on Windows Server 2018 R2 Enterprise mean while i have installed the NMAP seem so helpful, though its abit late here i have to break off until tomorrow morning , i really appreciate Sean , will get back to you tomorrow
 
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