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Manca Weeks
Asked: 2011-07-25 06:44:29 +0800 CST

How do I determine what my DHCP server is?

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I have a sad network left behind by some careless administrators - I am in the process of figuring out exactly what services are running where, not excluding the possibility that some services are running from two places at once, which is tons of fun.

There are two Windows Server 2003 servers, one Windows Server 2008 server with Exchange 2010 on it and a SonicWall TZ210 between the LAN and the WAN. Computers connected via DHCP reveal the gateway IP address that corresponds to the SonicWall unit, however it doesn't have DHCP enabled.

Where and how might I discover what is running DHCP so I could administer it? I am also concerned about internal DNS and Windows domain services as there appears to be confusing information on the network that conflicts with itself.

windows-server-2008 windows-server-2003 internal-dns dhcp

5 Answers

  1. ipconfig /all will show you the location of your DHCP server. There's a line item that says "DHCP Server"

    If you want to use ninja skills, you can use the command ipconfig /all | find /i "DHCP Server"

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  2. Your gateway is not always the same thing (server, firewall, proxy, whatever) as your DHCP server. To find your DHCP server, go to the status of your network connection and go to the details and find the "DHCP Server" address.

    Chances are good that it's a Windows DHCP server, so if you open up the DHCP MMC snapin and click on Action => Managed authorised DHCP servers it should hopefully list the DHCP servers that are authorised in Active Directory. You can then manage the DHCP server(s) from that same console and see what scopes and options you have defined.

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  3. One can also list all of the authorized DHCP servers in the domain by issuing the command, e.g. if you need to have it inventoried via script:

    netsh dhcp show server

    There is also a way to view all of the authorized DHCP servers in the domain via ADSI Edit tool.

    1. Open ADSI Edit tool.
    2. Right click on root on the left pane and click Connect to.
    3. Choose Configuration in the Select a well known Naming Context: drop-down list.
    4. Navigate to "CN=NetServices,CN=Services,CN=Configuration,DC=yourdomain,DC=com".
    5. The list of authorized DHCP servers will be on the right pane.
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  4. On Windows-based networks, the dhcp server is almost never on the gateway and almost always on the domain controller(s). What you're describing sounds like a perfectly normal network setup to me.

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  5. I moved the DHCP server from my sole Windows server to my router. I just configured DHCP on the router then that night turned it off on Windows and on on the router. No problems.

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