How to find a lost DHCP server?!

Discussion in 'General Hardware' started by Mainframeguy, Apr 29, 2009.

  1. Mainframeguy

    Mainframeguy Debiant by way of Ubuntu Folding Team

    London, UK
    I cannot help but smile... things are a bit hectic at my new place of work to say the least - there are a number of networked servers and a LOT of kit in various states of reuse or recycling.... we have all sorts of kit like banks for mastering hard drives and cloning in batches, the statutory PAT tester, and one or two other interesting things....

    But the thing is (don;t ask me how) they have managed to "lose" their DHCP server - I mean it is still there networked and serving - but we do not know where it is! :ermm::laugh:

    What would you do in such an environment if this happened to you?

    Suggestions on a postcard please....
  2. Electronic Punk

    Electronic Punk Administrator Staff Member Political User Folding Team

    Copenhagen, Denmark
    You could query all your switches for the mac address if they are good enough.
    I can't quite remember how i did it but we kinda knew that anything on the first interface was on another switch but anything else plugged in on others was generally connected directly to that switch.
  3. LordOfLA

    LordOfLA Godlike!

    Maidenhead, Berkshire, UK
    turn stuff off until it breaks :D

    Failing that ipconfig on the command prompt and windows will tell you the IP address of the DHCP server - you then just need to find the machine with the same ip address :)
  4. Xie

    Xie - geek - Subscribed User Folding Team

    NY, USA
    During a networking class I took ages ago my professor had a story like this. They had a server that had been running for ages, but then came time to do something to it and they couldn't locate it. In the end they found it in a wall while running wiring if I remember correctly. :)
  5. X-Istence

    X-Istence * Political User

    Not running wiring, but following wiring:

    Original article from TechWeb is gone, but the WayBack machine has it archived:

    The Registers take on it:
  6. LeeJend

    LeeJend Moderator

    Fort Worth, TX
    1) Call up the guy who you replaced, who was being paid twice as much as you are, and beg him to tell you which one it is.

    2) Almost went with Lord's "switch stuff off" but decided getting the whole mess back up and running was risky. So I'm using the "unplug the network cables one at a time until DHCP addresses stop getting issued".
  7. hansrijf

    hansrijf sh! it stinks Folding Team

    Amsterdam, The Netherlands
    isn't there some sort of programm that graphically maps your network? If you see, on this map, a computer that is close to it and you know where this pc is then you will not have to look so hard. Further on, is a DHCP server not close to a modem or router or something like that ( i am a network nitwit)?
  8. mlakrid

    mlakrid OSNN BASSMASTER Political User Folding Team

    If you know the server I woudl assume you know the server name... so it would be a 4 step process:

    1) From Cmd Prompt: NSLOOKUP (servername) This will give you the IP...

    2) Then once you know the IP, from the command prompt: tracert (IP)

    3) Now using the tracert you should know the location of where the last switch/router in the line

    4) loginto switch/router (show all interfaces) and then cable trace the cable/fiber from the port to the device...

    Good Luck MFG...

    Mike A!