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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.

Peter Mortensen
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Manca Weeks
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5 Answers5

36

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"

Nixphoe
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  • Found the DHCP server - it's running on one of the Windows 2003 servers. Wonder if it would be safe for me to move that service to the SonicWall instead. I am trying to eventually create conditions to be able to remove the 2 WIndows 2003 servers... – Manca Weeks Jul 24 '11 at 14:56
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    Personally I don't know why you would move the DHCP to the SonicWall. I run DHCP on my Domain Controllers - it's not exactly resource intensive, and it just works™ without any real drama. Is there a compelling reason you have to move it to the SonicWall? – Ben Pilbrow Jul 24 '11 at 15:11
  • Yes, I need to get rid of the two old Windows 2003 servers as they will be replaced by a new Mac OS X server. So I need to transition services away from those two... I am only keeping the Exchange 2010 (Windows 2008) server. – Manca Weeks Jul 24 '11 at 16:17
  • @Manca OK, so assuming the 2003 boxes are your Domain Controllers, where are you moving Active Directory to? – Ben Pilbrow Jul 24 '11 at 16:23
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    What's the function of the OS-X server in this network? It doesn't seem like a good fit. – Joe Internet Jul 24 '11 at 16:45
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    @Manca - This whole thing sounds like really bad plan. If you're keeping Exchange, you probably want to keep Active Directory. And if you want to keep Active Directory, you want Active Directory to also be both the dhcp and the dns server, so that computers joined to the Active Directory domain will do name resolution correctly. If you really want to convert to an OS X-based environment (and if you have any number of windows PCs, this is a questionable move), you should ditch exchange as well and use the OS X's mail server. – Joel Coel Jul 24 '11 at 18:58
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    @Joel if you're planning on keeping Exchange you don't "probably want to keep Active Directory", **Active Directory is *required***. If you take Active Directory away from Exchange (or try to move it on to the Exchange server for that matter) *it will burst into flames*. – Ben Pilbrow Jul 24 '11 at 19:02
  • A note about ipconfig - this answer only works if you run it from a DHCP client with DHCP enabled. It can sometimes be difficult to track down a DHCP enabled client. (In my case, the office is remote, so I can't just boot up a workstation, and all of our servers are on a separate vlan and static IP anyway. There are *no* leases on the AD authorized DHCP server in that office, which makes me wonder where that office is going for DHCP... Point being, ipconfig on a DHCP client isn't a viable option for me.) – Thomas Aug 10 '15 at 23:20
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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.

Ben Pilbrow
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4

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.
Volodymyr Molodets
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    can you check that, i got: The following command was not found: dhcp show server. `C:\>netsh dhcp show server The following command was not found: dhcp show server. C:\>netsh dhcp list - Lists all the commands available. help - Displays help. ? - Displays help. trace - Enable or disable tracing for DHCP client, Dump the last 100 traces. ` – Tilo Mar 13 '18 at 20:31
  • @Tilo does https://serverfault.com/questions/203889/netsh-dhcp-isnt-working-on-windows-server-2008 help? – mwfearnley Nov 08 '19 at 15:35
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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.

Joel Coel
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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.

Jim Blizard
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